Biology and Chemistry Questions -

What is the formula for Atom economy?

% atom economy = mass of desired product / total mass of reactants x 100

Spontaneous reaction

A reaction which occurs by itself.

After exercise, some ATP is used to re-establish the resting potential in axons. Explain how the resting potential is re-established. (2)

Active transport; Of sodium out of axon and potassium in

Suggest a reason for the shape of the curve between points C and D. (1)

All active sites occupied

What is the empirical formula?

An empirical formula is the simplest ratio of whole number atoms of each element in a compound.

Colour of Cu2+ metal aqua ion in solution

Blue

How long is a C-C bond? How long is a bond between 2 adjacent carbon atoms in a benzene ring? How long is a C=C bond?

C-C: 154 pm Bond between 2 adjacent carbon atoms in a benzene ring: 140 pm C=C: 135 pm

Producing and using biofuels from corn ethanol results in a negative percentage change in carbon dioxide production. Explain why. (2)

CO2 taken up in photosynthesis; More is taken up than is produced when it is used

Rate constant (k)

Constant of proportionality in the rate equation

[Ar] 4s1 3d10

Copper electron configuration

Explain the effect of the parasympathetic division of the autonomic nervous system on cardiac output. (2)

Decreases activity of SA node; Decreases rate of contraction of heart muscle

The student measured the water loss in milligrams. Explain the advantage of using ten leaves when taking measurements in milligrams. (1)

Decreases chance of error

Name the process by which oxygen passes from an alveolus in the lungs into the blood. (1)

Diffusion

Describe how a Pacinian corpuscle works. (5)

During resting potential sodium channels are too narrow to allow sodium ions through; When pressure is applied, membrane stretches; Sodium ion channels open; Sodium ions enter causing depolarisation of membrane; Causing generator potential which creates an action potential

Why do cone cells only respond to a high intensity of light? (3)

Each cone cell connected to a single neurone; So cannot combine to help exceed the threshold value and create a generator potential; Iodopsin requires high light intensity for its break down to create a generator potential

What are the main reasons for conservation? (2)

Ethical reasons; Economic reasons - maintains biodiversity. Species possess many genes that may be useful in the future

State which is the stronger base, ammonia or ethylamine. Explain your answer

Ethylamine alkyl group is electron releasing/donating OR alkyl group has (positive) inductive effect increases electron density on N(H2) OR increased availability of lp OR increases ability of lp (to accept H(+))

Substance made when [Fe(H2O)6]2+ reacts with sodium carbonate

FeCO3 Green Ppt

What can you assume [OH-] is for a strong base? What equation do you use to caluclate [H+] from [OH-]?

For a strong base, you can assume [OH-] = strong base concentration. Kw = [H+][OH-]

What bond is formed between monosaccharides? (1)

Glycosidic bond

Give the equation that links gross productivity and net productivity. (1)

Gross productivity = net productivity + respiratory loss

Chlorine + Water in Sunlight

H+, Cl- and O2 are produced, green Cl2 fades as it reacts to form O2 (colourless)

What reagents/condtions are used in the conversion of bromopropane to propylamine?

H2 with a nickel catalyst OR HCl with a tin catalyst

Write an equation for the dissociation of a water molecule

H2O ⇌ H+ + OH-

Write an equation for the dissociation of methanoic acid.

HCOOH ⇌ HCOO- + H+

The scientist measured the uptake of oxygen by the mitochondria during the investigation. The uptake of oxygen decreased when malonate was added. Explain why. (2)

Hydrogens not passed to ETC; Oxygen used as final electron acceptor

4s

In Period 4 transition metals, from which subshell are electrons removed first?

homogeneous

In the same state as the reactants

Describe and explain how intensive rearing of domestic livestock would affect the amount of energy absorbed from gut of consumers. (1)

Increase because fed food with high nutritive value

Why can insulin not be taken orally? (2)

It is a protein; Would be digested

Conditions for Nucleophillic Substitution to produce nitriles

KCN dissolved in ethanol or water heat under reflux

1 1.675 x 10^-27 kg 0 0

Neutron relative mass, actual mass, relative charge and actual charge

(Refer to exam q) Figure 4 shows a section through a human eye. Figure 5 shows the distribution of rods and cones in the retina of the human eye. Use figures 4 and 5 to explain why no image is perceived when rays of light strike the retina at the point marked P. (1)

No rods or cones at P

Explain what is meant by a recessive allele. (1)

Only expressed in the phenotype when homozygous alleles are present

Oestrogen only affects target cells. Explain why oestrogen does not affect other cells in the body. (1)

Other cells do not have the oestrogen receptors

Colour of Co2+ metal aqua ion in soln

Pink

h

Planck's constant

Order of Reaction

Power of concentration term (in rate equation)

What is hydrogen-1 NMR also referred to as? What does the number of peaks on a proton NMR spectrum tell you? What does the relative area under each peak tell you?

Proton NMR How many different hydrogen environments are present in a molecule. The relative number of hydrogen atoms in each environment (i.e. a ratio).

Bronsted Lowry base

Proton acceptor

Buffer solution

Resists change in pH for the addition of small amounts of acid or base. (It is also able to maintain its pH upon dilution with water).

The anaerobic digester has a cooling system, which is not shown in the diagram. Without this cooling system the digester would soon stop working. Explain why. (2)

Respiration causes release of heat; Enzymes would be denatured

Describe the light-independent reactions of photosynthesis and explain how they allow the continued synthesis of hexose sugars. (6)

RuBP combines with CO2; to form gylcerate 3-phosphate; using ATP; and reduced NADP; 2 molecules of TP form hexose; all RuBP is regenerated;

Which two structures produce amylase? (2)

Salivary glands; Pancreas

Describe how the action of microorganisms in the soil produces a source of nitrates for crop plants. (5)

Saprophytes feed on nitrogen-containing substances and release ammonia; ammonia is converted into nitrite; Nitrite is converted into nitrate; by nitrifying bacteria; Nitrogen is converted to ammonia; by nitrogen-fixing bacteria in soil

Molecules in which only single bonds exists between atoms

Saturated molecules?

What is the type of muscle that is used consciously? (1)

Skeletal muscle

Weak Acid

Slightly Dissociate

Applying very high concentrations of fertiliser to the soil can reduce plant growth. Use your knowledge of water potential to explain why. (2)

Soil will have lower water potential than roots; Osmosis from plant will occur

Oxidising agent

Something that accepts electrons and gets reduced.

What is mean bond enthalpy?

The average energy need to break a certain type of covalent bond, averaged over a range of compounds in which the value is different

Suggest two reasons for the recent increase in tuberculosis in developed countries. (2)

The development of resistant strains of the bacteria; Increase in HIV

Enthalpy of hydration

The enthalpy change when one mole of gaseous atoms are dissolved in water

The rate of water movement in the upper branches was different from the rate of water movement in the trunk. Describe how. (2)

The maximum rate is higher in the branches; It reaches the peak earlier in the day in the branches

Ionisation Enthalpy

The minimum amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state.

What is meant by 'activation energy'? (1)

The minimum amount of energy required to bring about a reaction

Cell potential

The voltage between two half cells in a electrochemical cell.

Standard electrode potential

The voltage measured under standard conditions when a half cell is connected to a standard hydrogen electrode.

Why does the trachea have rings of cartilage around it? (1)

To support it and prevent it collapsing as the air pressure inside falls when breathing in

Cyanide prevents oxygen acting as the final electron acceptor in the electron transport chain. Explain how cyanide stops ATP production by mitochondria. (2)

Transfer of electrons down the chain stops; No release of energy, to phosphorylate ADP;

What is the function of the SER? (1)

Transports proteins

Which blood vessels do the atria receive blood from? (1)

Veins

Acidic buffer

Weak acid and a salt of a weak acid. (Or a weak acid partially neutralised with a strong base)

6.02 x 10^23 particles

What is Avogadro's constant?

n = m/Mr

What is the equation relating n, m and Mr?

pV = nRT

What is the ideal gas equation?

Atomic number

What quantity is looked at in applying Cahn-Ingold-Prelog Priority Rules?

Bidentate

When a ligand can form two co-ordinate bonds in a complex ion.

Multidente

When a ligand can form two or more coordinate bonds in a complex ion.

What is meant by geographical isolation? (1)

When a physical barrier prevents two populations from breeding with each other

Light fractions and alkenes are in higher demand and more valuable.

Why are heavy fractions cracked to make smaller ones (and alkenes)?

Explain what is meant by succession (2)

change in community over time; change is due to species present

Units of rate

mol dm^-3 s^-1

How can you reduce the negative effects of cisplatin? Why is cisplatin still used as a chemotherapy, despite its negative side effects?

1. Low dosages 2. Targeting the tumour (e.g. nanoparticle generators) The long-term postivie effects (curing cancer) outweigh negative short-term effects.

What are the products of benzene nitration reactions used for?

1. Nitro compounds can be reduced to form aromatic amines, which make dyes and pharmaceuticals. 2. Some nitro compounds can be used as explosives.

What is the displayed formula?

A displayed formula shows how all the atoms are arranged and all the bonds between them

What is the trachea? (1)

A flexible airway made of muscle and lined with ciliated epithelium and goblet cells

What is a tropism? (2)

A growth movement of part of a plant; In response to a directional stimulus

Free energy change ΔG

A measure which links enthalpy and entropy change to predict whether a reaction is feasible. ΔG = ΔH-TΔSsystem

Complex ion

A metal ion surrounded by coordinately bonded ligands.

What are 1st order kinetics? What are 2nd order kinetics?

A reaction whose rate equation has a total order of 1. A reaction whose rate equation has a total order of 2.

How do synapses allow a single stimulus to create a number of simultaneous responses? (1)

A single impulse along one neurone can be transmitted to a number of different neurones at a synapse

What is a buffer?

A solution that resists large changes in pH when small amounts of acid or base are added, or when it's diluted

What is a free radical? What makes them so reactive?

A species with an unpaired electron, which makes them very reactive.

Root pressure moves water through the xylem. Describe what causes root pressure. (3)

Active transport of salts into the xylem; by endodermis; lowers water potential in xylem

Describe how the resting potential of a neurone is maintained. (2)

Active transport of sodium ions back out and potassium in; Less permeable to sodium ions

Give one way in which active transport differs from facilitated diffusion. (1)

Active transport requires energy

Ions enter a root hair cell from the soil. Describe how. (3)

Active transport; Against concentration gradient; Energy required;

(Refer to exam q) The graph shows the effect of concentration on the rate of uptake of magnesium ions by root hair cells. For curve Y name the process the cells are using to absorb magnesium ions between concentrations A and B. Use information in the graph to explain your answer. (2)

Active transport; Occurs against a concentration gradient because there is no uptake in curve Z

How is body temperature regulated in ectotherms? (3)

Adapt behaviour to changes in the external temperature; Expose themselves to sun; Take shelter

Describe a biochemical test to identify a reducing sugar such as maltose. (2)

Add Benedict's reagent and heat; Reducing sugar indicated by red/orange/brown colour

Describe how you would use a biochemical test to show that a reducing sugar is present. (2)

Add Benedict's reagent and heat; Reducing sugar indicated by red/orange/brown colour

Lactase is an enzyme. Lactose is a reducing sugar. Describe how you could use the biuret test to distinguish a solution of the enzyme, lactase from a solution of lactose. (1)

Add Biuret reagent to both solutions. Lactase will give a purple colour

How can you help to confirm the prescence of 1-chloropropane?

Add NaOH then acidify with HNO3 then add AgNO3 solution and you see a white precipitate.

Describe a biochemical test to identify starch. (2)

Add iodine solution to sample; The presence of starch is indicated by a blue / black colour

The over-application of fertiliser increases the rate of leaching. Explain the consequences of leaching of fertiliser into ponds and lakes. (3)

Algal bloom occurs; Light is blocked out; Plants can't photosynthesise and so die

Explain what is meant by the ecological term, population. (1)

All organisms of one species in a habitat at a particular time

Explain the advantage of growing papaya plants from tissue culture rather than from seeds. (1)

All plants will have desired characteristics

Homogeneous reaction

All reactants and products are in the same state

Explain why the curves for 27 °C and 37 °C level out at the same value. (2)

All substrate changed into product; They had the same initial substrate concentration

Explain what is meant by a community. (1)

All the populations living in a particular habitat at the same time

Asthma reduces the efficiency of gas exchange in the lungs. Explain why. (4)

Allergens cause white blood cells on the linings of the bronchi to release a chemical called histamine; this causes the epithelial cells to secrete larger quantities of mucus; and causes the bronchiole muscles to contract and so constricts, reducing flow of air; So it is more difficult to ventilate the lungs and the diffusion gradient is reduced

What is the cause of asthma? (2)

Allergens; such as pollen, animal fur, air pollutants etc

Nitrogenase catalyses the reduction of nitrogen during nitrogen fixation. The reaction requires 16 molecules of ATP for each molecule of nitrogen that is reduced. Nitrogen gas is the usual substrate for this enzyme. Name the product. (1)

Ammonia

Transition Metal

An Element that has an incomplete d sub-shell in either its atoms or one or more of its ions

What is an aliphatic compound? What can a quaternary ammonium ion also be called? Draw the structures of a primary, secondary and tertiary aliphatic amine and a quaternary ammonium ion. Draw the structure of a primary aromatic amine.

An aliphatic compound is a compound containing carbon and hydrogen joined together in straight chains, branched trains or non-aromatic rings. A tetramethylamine Refer to big sheets

What is a lone pair?

An unshared electron pair in a covalent bond.

(Refer to Jan 2013 paper) The students' results are shown in the table. Explain the relationship between the number of leaves removed from the plant shoot and the mean rate of water uptake. (3)

As number of leaves are reduced there are fewer stomata; so less evaporation; so less cohesion pulling the water up

How does substrate concentration affect enzyme action? (3)

As substrate concentration increases the rate of reaction increases; because at low substrate concentrations there are too few substrate molecules to occupy all the available active sites; As substrate is added the active sites become filled until the point where all of them are occupied and there is no further increase in the rate of reaction

Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta. (5)

Atrium has higher pressure than ventricle due to contraction; Causing the atrioventricular valve to open; Now the ventricle has higher pressure than the atrium and the aorta due to contraction; So the atrioventricular valve closes; and the semilunar valve opens

Explain the importance of reflex actions. (2)

Avoids damage to tissues; Helps escape from predators

Solubility + Use of Ba(OH)2

Ba(OH)2 is very soluble in water hydroxide ions are produced so the solution is very alkaline as a result of Ba(OH)2 dissolving Ba(OH)2 + aq → Ba2+ + 2OH-

What are the three types of pathogen? (1)

Bacteria, viruses and fungi

The scientists' hypothesis was that there was a relationship between the starch grains in the root tip cells and the bending and direction of growth of lateral roots. Does the information in the diagram support this hypothesis? Give reasons for your answer. (3)

Bending starts when grains form; More bending as grains increase in number; However could be related to vacuole

Give all the genotypes which would result in a brown-shelled snail. (1)

CBCB, CBCP and CBCY

How can a synapse prevent a new action potential being created? (3)

Chloride ion channels can be kept open; Influx of chloride ions; Making postsynaptic membrane more negative than at resting potential

Describe how the control group should have been treated. (2)

Chocolate with no flavenoids; Otherwise the same as experimental group

Why is transplatin a bad anti-cancer drug?

Cl ligands are too far apart to effectively bond to 2 adjacent guanine bases and subsequently cause kinks in a DNA chain.

Write an equation for the reaction between chlorine and cold, dilute aqueous sodium hydroxide. Give two uses of the resulting solution

Cl2 + NaOH → NaClO + NaCl + H2O, bleach, disinfectant

Colour of Chlorine and Chloride

Cl2 → Greenish gas Cl- → very pale green solution, almost colourless

What is the general formula of an alkene? Are they saturated or unsaturated? Why are they so reactive?

CnH2n They are saturated, due to containing double bonds, not only single bonds. Their double bonds have a high electron density, as they contain two pairs of electrons, so they attract electrophiles.

Oral rehydration solutions (ORS) are used to treat diarrhoeal disease. What does an ORS consist of and how does it work? (5)

Contains glucose; And sodium; The sodium and glucose are taken up from the lumen; Which increases the water potential gradient; So water is taken up by cells by osmosis

A triglyceride does not contain sucrose or bond X. Give one other way in which the structure of a triglyceride is different to olestra. (1)

Contains three fatty acids

Calculate the rate at which person A breathed air out of his lungs between 0 and 3 seconds. Show your working. (0 = 6.5, 3 = 2.3) (2)

Correct answer 1.4; vol. air breathed out = 6.5 - 2.3 / 4.2 dm3

For curve Z explain why the rate of uptake increases between B and C. (1)

Diffusion is proportional to the concentration gradient

(Refer to Jan 2012 paper) Use the diagram to explain what is meant by an unsaturated fatty acid. (Shows the structure of a triglyceride molecule) (2)

Double bonds present; between carbon atoms

What happens to melting point as you go down Group 2? Where does the trend change and why?

Down group 2, generally, melting point decreases, but the trend changes at magnesium as crystal structure (arrangement of metallic ions) changes

Arteries and arterioles take blood away from the heart. Explain how the structures of the walls of arteries and arterioles are related to their functions. (6)

Elastic tissue stretches under pressure; And recoils; Which evens out pressure; Muscle contracts; Which constricts vessel; To change flow; Epithelium is smooth; To reduce friction

Why doesn't chlorobenzene react with ammonia under normal conditions?

Electron dense ring (benzene) and pi cloud repel nucleophiles like ammonia. The C-Cl bond is stronger in chlorobenzene than in a halogenoalkane, as the C-Cl bond is less polar than in the haloalkane. Resonance stabilisation occurs between benzene ring and Cl atom.

Explain why an electron microscope shows more detail of cell structure than a light microscope. (2)

Electron microscope has a greater resolving power; Electron beams have a shorter wavelength

Nucleophile

Electron pair donor

0.0005 9.11 x 10^-31 kg -1 -1.60 x 10^-19 C

Electron relative mass, actual mass, relative charge and actual charge

Why are Transition metal complexes coloured?

Electrons in d orbital absorb UV light. The more UV light absorbed the bigger the gap in energy of the electrons. Some gain enough energy to move up to the next energy level. I.E the electrons have different amounts of energy. They absorb different wavelengths of light.

What did Bohr's atom model show?

Electrons only exist in fixed orbits and not anywhere in between. Each Shell has a fixed energy. When an electron moves between shells, electromagnetic radiation is emitted or absorbed. Because the energy of the shells is fixed, the radiation will have a fixed energy.

In benzene, what are delocalised electrons?

Electrons that don't belong to a specific carbon atom but are shared between them all.

What type of mechanism is the reaction between benzene and ethanoyl chloride?

Electrophilic substitution

Sample dissolved in polar solvent and pushed through small nozzle at high pressure. High positive voltage is applied, causing each particle to gain 1 proton from the solvent and sample becomes gas made of cations

Electrospray ionisation

What is electrostatic attraction?

Electrostatic attraction holds positive and negative ions together - it is very strong.

The zoologist measured oxygen uptake per gram of body mass. Explain why he measured oxygen uptake per gram of body mass. (2)

Enables comparison; As animals differ in size

(Refer to June 2010) The diagram shows a cross-section of a blood vessel. Name layer C. (1)

Endothelium

(Refer to exam q) The table shows some properties of slow and fast muscle fibres. Endurance athletes, such as marathon runners, nearly always have a high proportion of slow muscle fibres in their muscles. Explain the benefit of this. (6)

Endurance athletes exercise for long periods of time; Respire aerobically; Slow fibres adapted to aerobic respiration; As they have many mitochondria; Which is the site of Kreb's cycle; Producing large amount of ATP

Why is bond breaking endothermic?

Energy is absorbed to break bonds

Why is bond making exothermic?

Energy is realeased when bonds form

Endothermic Reactions

Energy is taken up from the surroundings to the system, energy is needed to break bonds more than is released when the bonds are formed, so energy input is required to proceed. Products have more energy than reactants ∆H = positive (as energy is added to the system)

Give two ways in which the properties of ATP make it a suitable source of energy in biological processes. (2)

Energy released in small, suitable amounts; It is soluble

Exothermic Reactions

Energy's transferred from the system to the surroundings. The energy needed to break bonds is less than the energy released when bonds are formed. Products have less energy than reactants ∆H = negative (as energy is lost from the system)

Why is the refractory period important? (3)

Ensures that an action potential occurs in one direction only; Ensures that action potentials are separated from one another; Limits the number of action potentials

How do you calculate enthalpy changes via mean bond enthalpies?

Enthalpy change = Sum of bond enthalpies of reactants - sum on bond enthalpies of products

Electron Affinity

Enthalpy change when 1 mole of gaseous atoms Form 1 mole of gaseous negative ions

Enthalpy of Solution

Enthalpy change when 1 mole of solid dissolves in water to form aqueous ions

Describe how siRNA affects gene expression. (5)

Enzyme cuts large double-stranded RNA into smaller sections called siRNA; One siRNA strand combines with an enzyme; siRNA molecule guides enzyme to an mRNA molecule and pairs up its unpaired bases with mRNA's complementary bases; Enzyme cuts mRNA into smaller sections; mRNA unable of being translated into a polypeptide

Explain the shape of the curve between 30 oC and 50 oC. (Goes down) (3)

Enzyme denatured; Change in shape of active site of enzymes; Substrate no longer able to fit active site

(Refer to June 2010 paper) The diagram shows a cell from the pancreas. (K = Microvilli, J = Golgi apparatus, H = RER, G = Mitochondria, E = Lysosomes.) The cytoplasm at F contains amino acids. These amino acids are used to make proteins which are secreted from the cell. Place the appropriate letters in the correct order to show the passage of an amino acid from the cytoplasm at F until it is secreted from the cell as a protein at K. (2)

F H J E K

Implanon is a contraceptive device that is inserted under a woman's skin and prevents pregnancy for up to three years. It is a small rod that continuously releases progesterone into her blood. This progesterone prevents fertilisation from taking place. Explain how Implanon prevents fertilisation from taking place. (4)

FSH inhibited; Follicle not stimulated; LH inhibited; Ovulation prevented

Describe the two hormones which are released from the pituitary gland in the oestrous cycle. (4)

Follicle-stimulating hormone (FSH); stimulates development of follicles, which contain eggs, in the ovary and stimulates the follicles to produce oestrogen; Luteinising hormone (LH); causes ovulation to occur, stimulates ovary to produce progesterone

What is percentage yield and what is its formula?

For any reaction the actual mass of the product (actual yield) will be less than the theoretical yield. percentage yield = actual yield / theoretical yield x 100

Research workers have suggested that treating diabetes in humans by this method of gene therapy would be better than injecting insulin. Evaluate this suggestion. (4)

For: Avoids pain of injections; Longer lasting; Against: Rats are different to humans; Substitute insulin may be rejected by the body

Suggest one ethical argument for and one against stem cell research. (2)

For: It is wrong to allow human suffering when there is a possibility of alleviating it by obtaining information from research; Against: Embryos should be given same respect as an adult person

A high concentration of galactose slows down the breakdown of lactose by lactase. Use your knowledge of competitive inhibition to suggest why. (2)

Galactose is a similar structure to lactose and is complementary to the active site of the enzyme; Galactose binds with active site of enzyme; So less substrate is able to bind with the active site

Would dimethylamine be a solid, liquid or a gas at room temperature, given that ethylamine is a gas at room temperature?

Gas - both compounds have the same Mr. Both types of molecule have hydrogen bonds between them.

Describe how you would place quadrats at random. (2)

Generate random numbers by drawing some from a hat; Lay out two long tape measures at right angles along two sides of the study area and use the numbers as coordinates to find where to position each quadrat

The Amazonian forest today contains a very high diversity of bird species. - Over the last 2 000 000 years, long periods of dry climate caused this forest to separate into a number of smaller forests. - Different plant communities developed in each of these smaller forests. - Each time the climate became wetter again, the smaller forests grew in size and merged to reform the Amazonian forest. Use the information provided to explain how a very high diversity of bird species has developed in the Amazonian forest. (5)

Geographical isolation; Mutation; Different selection pressures; Adapted organisms survive and breed; Increase in allele frequency

What are giant covalent structures

Giant covalent structures have huge networks of covalently bonded atoms. Carbon often forms this type of structure because they can each form four strong covalent bonds.

Why does reactivity increase down Group 2?

Group 2 elements lose electrons when they react and as you go down Group 2, first and second ionisation energies decrease (number of shells increases so outer electrons get further from the nucleus and more shielded from its attraction by extra inner shells, so become less attracted to the nucleus), so electrons take less energy to remove and are removed more easily.

What DNA base does cisplatin react with? How?

Guanine - nitrogen atom in a guanine base replaces a chlorine atom in coordinately bonding with Pt atom in the middle of cisplatin complex.

Describe how the banding pattern will be different when the muscle fibril is contracted. (2)

H zone narrows; Light band narrows

Write an equation for the equilibrium for blood buffer.

H+(aq) + HCO3-(aq) ⇌ CO2(aq) + H2O(l)

Identification of Halide + H2SO4 products

HX → white steamy fumes Br2 → red fumes SO2 → colourless acidic gas H2S → bad eggy smell S → yellow solid I2 → purple fumes/black solid

The endodermis controls the entry of substances into the xylem. Explain how. (2)

Has a casparian strip; So water cannot move through apoplast

Cholera bacteria can be viewed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). Give one advantage of using a TEM rather than a SEM. (1)

Has a higher resolution

4

How many bonds do carbon atoms form in diamond?

3

How many bonds to carbon atoms form in graphite?

How do cationic surfactants remove grease?

Hydrocarbon tail binds to non-polar substances like grease, while cationic (positively charged) head dissolves in water.

What is hydrogen bonding?

Hydrogen bonding is the strongest intermolecular force. it only happens when hydrogen is covalently bonded to fluorine, nitrogen or oxygen because they're very electronegative and can pull the bonding electrons away from the hydrogen. Substances with hydrogen bonding have higher melting and boiling points because of the extra energy needed to break the hydrogen bonds.

Name the type of chemical reaction shown in this equation. (1)

Hydrolysis

What conclusion can be made from the results for treatment (b)? (1)

IAA is produced in the root tip

It is important that a neurotransmitter such as serotonin is transported back out of synapses. Explain why. (3)

If not removed keeps binding to receptors; Keeps causing action potentials in post-synaptic membrane Prevents information being carried across synapse

What is the trend in solubility of Group 2 ionic compounds?

If the compound anion is singly charged (e.g. OH-), solubility increases down Group 2. If it is doubly charged (e.g. SO4^2-), solubility decreases down Group 2.

What is incomplete combustion?

If there's not enough oxygen, hydrocarbons cannot combust incompletely and you get a particulate carbon soot and carbon monoxide gas as well as carbon dioxide. This is bad because carbon monoxide gas is poisonous.

Van der Waals forces Permanent dipole-dipole forces Hydrogen bonding

In order of increasing strength, what are the 3 main types of intermolecular force?

All cells possess the same genes and yet a skin cell can produce the protein keratin but not the protein myosin, while a muscle cell can produce myosin but not keratin. Explain why. (4)

In skin cells the gene coding for keratin is expressed but not gene for myosin; Genetic code for keratin translated into protein; In muscle cells the gene coding for myosin is expressed but not gene for keratin; Genetic code for myosin translated into protein

People suffering from emphysema have less elastic tissue in their lungs. Explain how this affects the efficiency of gas exchange in the alveoli. (3)

Inability to recoil and stretch; Decreased concentration gradient; So less oxygen enters the alveoli and less CO2 leaves the alveoli

What is rate of reaction?

Increase in concentration of product over time

Using figure 2, give one example of how positive feedback is involved in the secretion of FSH. (2)

Increase in oestrogen concentration after 11 days; stimulates rise in FSH

Use information from the table to explain how training has caused the resting heart rate of this athlete to be lower. (2)

Increased strength of contraction; Increase in stroke volume - more blood leaves heart in each beat

Using information from the table, explain the increase in mean rate of oxygen consumption. (2)

Increased temperature leads to faster enzyme activity; Faster rate of respiration and hence oxygen consumption

What is the advantage to organisms of being able to respond to stimuli? (3)

Increases chance of moving out of an unfavourable environment into a favourable one; Increases chance of survival and reproduction; There is a selection pressure favouring organisms with these advantageous response alleles

Reducing Strength of Halide ions

Increases down the group - more easily oxidised,

The stomata on the leaves of pine trees are found in pits below the leaf surface. Explain how this helps to reduce water loss. (2)

Increases humidity around stomata; So that the water potential gradient is reduced

(Refer to exam q) The drawing shows some of the structures involved in ventilating human lungs. Name structure A. (1)

Intercostal muscle

What causes the formation of the secondary and tertiary structures of proteins? What is the importance of the cause?

Intermolecular forces between different sections of the chain causing the amino acid chains to fold or twist. These intermolecular forces are important because the 3-d shape of a protein is vital to how it functions.

It would not be valid to conclude from the investigations described in this question that an increase in carbon dioxide concentration would reduce crop losses due to caterpillars. Give two reasons why this conclusion might not be valid in field conditions. (2)

Investigation refers to a single species and other species might not respond in the same way; Investigation carried out in greenhouse where conditions controlled

The part labelled Z is involved in facilitated diffusion of substances across the membrane. Give one similarity in the way in which active transport and facilitated diffusion transport substances across the membrane. (1)

Involves carrier proteins

(Refer to June 2010 paper) During an action potential, the permeability of the cell-surface membrane of an axon changes. The graph shows changes in permeability of the membrane to sodium ions (Na+) and to potassium ions (K+) during a single action potential. Explain the shape of the curve for sodium ions between 0.5 ms and 0.7ms. (3)

Ion channel proteins open; Influx of sodium ions; This makes the inside of axon less negative

Ions enter region with no electric field and drift through it, lighter ions (and those with lower m/z ratios) moving fastest

Ion drift

What are Ions?

Ion have different numbers of protons and electrons. Negative ions have more electrons than protons and positive ions have fewer electrons than protons.

What is ionic bonding?

Ionic bonding is bonds that have electrostatic attraction. When oppositely charged ions form an ionic bond you get an ionic compound.

What is the electrical conductivity of an ionic compound?

Ionic compounds conduct electricity when they're molten or dissolved - but not when they're solid. The ions in a liquid are free to move and carry a charge. In a solid they're in a fixed position by the strong ionic bonds.

What is the melting point for ionic compounds?

Ionic compounds have high melting points. The giant ionic lattices are held together by strong electrostatic forces. It takes lots of energy to overcome these forces, so melting points are very high.

What is the solubility of ionic compounds?

Ionic compounds tend to dissolve in water. Water molecules are polar - part of the molecule has a small negative charge and the other bits have small positive charges. The water molecules pull the ions away from the lattice and cause it to dissolve.

Perfect Ionic Model

Ions can be regarded as perfect spheres

Atoms with the same number of protons but different numbers of neutrons

Isotopes

Marram grass grows on a sand dune. Describe how you would investigate the distribution of marram grass from one side of the dune to the other. (3)

Lay line from one side of the dune to the other; Place quadrats at regular intervals along the line; Count percentage cover in quadrats

The human heart has four chambers. In which one of the four chambers of the human heart does pressure reach the highest value? (1)

Left ventricle

Use the information provided and your knowledge of the light-independent reaction to explain why the yield from soya bean plants is decreased at higher concentrations of oxygen. Phosphoglycolate is not used in the light-independent reaction. (3)

Less glycerate 3-phosphate produced; Less triose phosphate to form organic molecules; Less RuBP regenerated

A person with emphysema found it difficult to carry out exercise. Explain why. (3)

Less oxygen reaches the muscles; Oxygen is needed for aerobic respiration; Less energy is released for exercise

DNP inhibits respiration by preventing a proton gradient being maintained across membranes. When DNP was added to isolated mitochondria the following changes were observed: - less ATP was produced - more heat was produced - the uptake of oxygen remained constant. Explain how DNP caused these changes. (3)

Less proton movement so less ATP produced; The energy not used to produce ATP is released as heat instead; Oxygen is used as the final electron acceptor

The net productivity of the plants in the field was higher in August than in July. Use the equation in part (b)(i) and your knowledge of photosynthesis and respiration to suggest why. (2)

Less respiration; Lower energy loss

Explain the rise in the amount of ribulose bisphosphate after the carbon dioxide concentration is reduced. (1)

Less ribulose phosphate is used to combine with carbon dioxide

Suggest how the addition of NBPT to urea fertiliser could result in increased growth of crop plants. (3)

Less urea broken down; Urea converted to nitrate; Used to produce protein

Explain how xylem tissue is adapted for its function. (4)

Long cells with no end walls; to create continuous water columns; It is thick; To withstand tension

What are the problems associated with drugs to control tuberculosis? (2)

Long time period so people may stop taking it; Resistant strains of the bacteria

Explain why the pH of an acidic buffer solution remains almost constant despite the addition of a small amount of sodium hydroxide.

M1 extra/added OH- removed by reaction with H+ or the acid M2 correct discussion of equm shift of acid dissociation to right (HX ⇌ H+ + X-) OR ratio [HX]/[X-] remains almost constant

Why can rod cells respond to a very low intensity of light? (3)

Many rod cells share a single neurone; Therefore the threshold value is exceeded; Low intensity is sufficient to break down rhodopsin, creating generator potential

Give two conditions for results from mark-release-recapture investigations to be valid. (2)

Marking does not affect survival; Sufficient time for marked individuals to mix within the population

What is the relative mass and charge on a neutron?

Mass 1 Charge 0

Mammals are endotherms; reptiles are ectotherms. Explain two advantages of endothermy over ectothermy. (2)

Metabolic reactions proceed more quickly; Better able to survive in different environments

What is metallic bonding?

Metal elements exist as giant metallic lattice structures. The outermost shell of electrons of a metal atom is delocalised, leaving a positive metal ion. The positive metal ions are attracted to the delocalised negative electrons.

Complex

Metal ion with ligands co-ordinately bonded to it.

Suggest how the student could have used his slide to find the number of stomata per cm2. (3)

Method of determining area of field of view; Count number of stomata in field of view; Repeats and calculation of mean

Methotrexate is a drug used in the treatment of cancer. It is a competitive inhibitor and affects the enzyme folate reductase. Explain how the drug lowers the rate of reaction controlled by folate reductase. (2)

Methotrexate is a similar structure to substrate and is complementary to active site; Less substrate binds to active site

Methotrexate only affects the rate of the reaction controlled by folate reductase. Explain why this drug does not affect other enzymes. (1)

Methotrexate is only a similar shape to a specific substrate

When methylbenzene reacts with ethanoyl chloride and aluminium chloride, a similar substitution reaction occurs but the reaction is faster than the reaction of benzene. Suggest why the reaction of methylbenzene is faster

Methyl group has (positive) inductive effect OR increases electron density on benzene ring OR pushes electrons OR is electron releasing electrophile attracted more or benzene ring better nucleophile

Solubility of Mg(OH)2

Mg(OH)2 is insoluble in water Mg2+ + 2OH- → Mg(OH)2 (simplest ionic equation) Mg(OH)2 suspension in water, will be slightly alkaline, pH9 so some hydroxide ions have been produced by dissociation

What is a pathogen? (1)

Microorganism that causes disease

Microorganisms make the carbon in polymers in a dead worm available to cells in a leaf. Describe how. (5)

Microorganisms are saprophytes; Secrete enzymes onto dead tissue which break down the complex molecules into smaller, soluble ones; The saprophytes absorb these small molecules by diffusion; Respiration by microorganisms produces carbon dioxide; Carbon dioxide taken into leaves through stomata

Explain how carbon-containing compounds present in the pine leaves that fall from the trees are absorbed and used for growth by fungi that live in the soil. (4)

Microorganisms are saprophytes; Secrete enzymes onto dead tissue which break down the complex molecules into smaller, soluble ones; The saprophytes absorb these small molecules by diffusion; Respiration provides energy for growth

(Refer to exam q) The drawing shows an electron micrograph of parts of epithelial cells from the small intestine. Name the structures labelled A. (1)

Microvilli

Give two adaptations that epithelial cells in the small intestine have for the absorption of food. (2)

Microvilli; Many mitochondria

The epithelial cells that line the small intestine are adapted for the absorption of glucose. Explain how. (6)

Microvilli; increase surface area for absorption; Many mitochondria; to release energy for active transport; Carrier proteins for active transport; Channel proteins for facilitated diffusion

How may a drug stimulate the nervous system? (3)

Mimick a neurotransmitter; Stimulate the release of more neurotransmitter; Inhibit the enzyme that breaks down the neurotransmitter

Activation energy

Minimum energy required for the reaction to occur

Some cells lining the bronchi of the lungs secrete large amounts of mucus. Mucus contains protein. Name one organelle that you would expect to find in large numbers in a mucus-secreting cell and describe its role in the production of mucus. (2)

Mitochondria; Releases energy which is necessary for protein synthesis

Suggest why it is important to prevent mixing of the blood in the two sides of the heart. (4)

Mixing of oxygenated and deoxygenated blood; would result in partially oxygenated blood reaching the tissues and lungs; This means supply of oxygen to tissues would be inadequate; and there would be a reduced diffusion gradient in the lungs, limiting the rate of oxygen uptake into the blood

How do you work out a substance's mole fraction? Its partial pressure?

Mole fraction (MF) = Number of moles of that substance/ Total number of moles in the gaseous equilibrium. Partial pressure = MF x total pressure

Why does increasing pressure/ concentration increase rate of reaction?

Molecules get, on average, closer together, so collide more frequently

A student carried out an investigation into the mass of product formed in an enzyme controlled reaction at three different temperatures. Only the temperature was different for each experiment. The results are shown in the graph. (Refer to exam q) Use your knowledge of enzymes to explain why the initial rate of reaction was highest at 55 °C. (2)

Molecules have more kinetic energy; So more enzyme substrate complexes formed

Saturated molecules?

Molecules in which only single bonds exists between atoms

Why does increasing temperature increase rate of reaction?

Molecules move faster so collide more frequently and more have energy at least activation energy when they collide, so many more successful collisions in a given time

Why is Titanium expensive?

Na/Mg cost, batch process (slower more labour intensive), Ar, Moisture removal (so TiCl4 isn't hydrolysed), high temperatures required

What reducing agent is oft used to reduce an aldehyde?

NaBH4 (sodium tetrahydridoborate(III) or sodium borohydride) dissolved in water with methanol.

What danger does sulfur dioxide have?

It can enter the atmosphere and react with rain water to form sulfuric acid, contributing to acid rain. Acid rain destroys trees and vegetation and corrodes buildings and statues and kills fish in lakes.

Data like these are often given as percentages of people dying from each cause. Explain the advantage of giving these data as percentages. (2)

It is easier to compare if the sample size is effectively the same; There are different numbers of people in each group

What is the oxidation state of a compound ion?

Its overall charge

Conditions for Nucleophillic Substitution to produce alcohols

KOH or NaOH in aqueous solution, heat under reflux

Conditions for Elimination to produce alkenes

KOH or NaOH in ethanol, heated

Substance made when [Co(H2O)6]2+ reacts with XS NaOH

No Change from dilute

Name two structures present in an epithelial cell from the small intestine that are not present in a cholera bacterium. (2)

Nuclear envelope; Mitochondria

What does NMR stand for? What are the two types and what information do they give? Why are these particles used?

Nuclear magnetic resonance 1. Carbon-13 NMR: tells you how carbon atoms in a molecule are arranged 2. Hydrogen-1 NMR: tells you how hydrogen atoms in a molecule are arranged Carbon-13 and hydrogen-1 nuclei contain an odd number of nucleons, so they have nuclear spin, so have a weak magnetic field, like a bar magnet. Also, they are the second most and most abundant isotopes of their elements, respectively.

What differences in energy absorption are you looking for in NMR spectroscopy?

Nuclei in a molecule feel different magnetic fields depending on their environments. Nuclei in different environment absorb different amounts of energy at different frequencies.

What is the equation for equilibrium constant, Kp, for gaseous equilibrium in the reaction aA + bB ⇌ dD + eE?

Kp = ((pA)^a x (pB)^b)/((pD)^d x (pE)^e)

What is thrombosis and how may it cause myocardial infarction? (6)

Occurs when an atheroma breaks through the endothelium of the blood vessel; This forms a rough surface that interrupts the otherwise smooth flow of blood; This may lead to the formation of a blood clot (thrombus); Which blocks the coronary artery; Reducing oxygen supply to the heart muscle; So the heart muscle is unable to respire

Geometric Isomerism

Occurs where there are two ligands of one type different to the other ligands.

This siRNA would only affect gene expression in cells infected with HIV. Suggest two reasons why. (4)

Only infected cells have HIV protein on surface; So carrier only attaches to these cells; siRNA base sequence complementary to one mRNA; Only infected cells contain mRNA of HIV

Use evidence from the diagram to explain that hairlessness is caused by a gene on the X chromosome. (1)

Only males are hairless

The pine trees in the forest have leaves all year. Explain how this results in a low species diversity of plants in the forest. (1)

Only plants which can photosynthesise with less light remain

What do optical isomers do to plane-polarised light? How does each enantiomer of the same molecule do it differently?

Optical isomers are optically active - they rotate plane-polarised light. One enantiomer rotates it clockwise, the other, anticlockwise.

1s,2s,3s,3p,4s,3d,4p,5s,4d,5p

Order for energy level energies from 1s to 5p

What is used to oxidise alcohols? What colour change occurs when it does oxidise an alcohol?

Oxidising agent: acidified potassium dichromate(VI) solution Colour change: orange → green, as orange Cr2O7^2- ions are reduced to green Cr^3+ ions

Explain why the oxygen concentration would change during this investigation. (1)

Oxygen is the final acceptor in the electron transport chain and is used to make water

In the presence of oxygen, respiration yields more ATP per molecule of glucose than it does in the absence of oxygen. Explain why. (5)

Oxygen is the final electron acceptor; Process of electron transport chain; Fate of pyruvate; Krebs cycle; Significance of ATP formed in glycolysis;

Explain why the pulse recordings in the doctor's surgery were taken when the men were lying down. (1)

Patients were at rest

Name the type of bond formed between the joined pair of amino acid molecules. (1)

Peptide

What are the symptoms of pulmonary tuberculosis? (4)

Persistent cough; Tiredness; Weight loss; Fever

Name C6H5COCH2CH3

Phenylpropanone

Explain the result you would expect with the enzyme. (1)

Lactase is a protein

The equation shows the reaction catalysed by the enzyme lactase. Complete this equation. Lactose + .............. ---> Glucose + .............. (2)

Lactose + Water; ---> Glucose + Galactose

Explain how three features of a plasma membrane adapt it for its functions. (6)

Phospholipid bilayer acts as a barrier and; allows non-polar substances to pass; Carrier proteins through the bilayer; allow facilitated diffusion; Extrinsic proteins; are used for cell recognition and act as antigens

How is the movement of ions controlled? (3)

Phospholipid bilayer of axon membrane prevents ions diffusing across it; Intrinsic proteins contain channels which open and close accordingly; Some intrinsic proteins actively transport ions in and out (sodium-potassium pump)

In June, young birds leave their nests and join the adults. Using mark-release-recapture to estimate the size of a blue tit population in June would not give reliable results. Explain why. (2)

Population changes; As young birds leave nest

Display the mechanisms and type of reaction and conditions needed for cyanide and propanal to make 2-hydroxybutanenitrile. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the conversion of 2-bromopropane to propene. Show all possible products and observations and roles of reagents.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the conversion of 2-bromopropane to propene. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the conversion of bromoethane to ethanol. Show all possible products and observations and roles of reagents.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the hydration of ethene using sulfuric(VI) acid. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the hydration of ethene. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the reaction of bromine water with ethene. Show all possible products and observations

Refer to big sheets

Write equations to show how burning bioethanol can be considered carbon neutral

Refer to big sheets

Give two reasons why the percentage of energy transferred between consumers is generally low. (2)

Respiration; Excretion

The student measured the rate of water uptake three times. Suggest how the reservoir allows repeat measurements to be made. (1)

Returns bubble to the start

The cardiac cycle is controlled by the sinoatrial node (SAN) and the atrioventricular node (AVN). Describe how. (5)

SAN sends wave of electrical activity across atria causing atrial contraction; AVN delays electrical activity; Allowing ventricles to fill before they contract; AVN sends wave of electrical activity down Bundle of His; Causing ventricles to contract

In some countries, pigs are reared in intensive units in which the temperature is controlled. Agricultural scientists investigated the effect of temperature on pig growth and on the efficiency with which the pigs converted food to biomass. In the investigation, the scientists used pigs of the same breed, with similar genotypes. Explain why. (2)

Same breed so similar alleles; So only temperature affects results

To how many decimal places do high resolution mass spectrometeras measure Ar and Mr to?

Several

Decreasing temperature

Shifts the equilibrium in the exothermic direction

How do you distinguish between a pair of stereo isomers?

Shine plane polarised light through them - they rotate plane polarised light in opposite directions.

A capillary has a thin wall. This leads to rapid exchange of substances between the blood and tissue fluid. Explain why. (1)

Short diffusion pathway

The length of mitochondria can vary from 1.5μm to 10μm but their width never exceeds 1μm. Explain the advantage of the width of mitochondria being no more than 1μm. (1)

Short diffusion pathway

How have mammals and birds living in cold climates adapted to these environments? (3)

Smaller surface area to volume ratio; Smaller extremities; Fat layers to insulate

Energy is transferred through an ecosystem. Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer. (6)

Some light not of appropriate wavelength; So efficiency of photosynthesis in plants is low; Energy is lost by consumers through respiration; and heat; Efficiency lower in older animals; Carnivores use more of their food than herbivores

Reducing agent

Something that donates electrons and gets oxidised.

Scientists who investigate disease may look at risk factors. What is a risk factor? (1)

Something that increases chance

What stationary and mobile phase are used in thin layer chromatography?

Stationary phase: glass, metal or plastic sheet coated with thin layer of silica gel (SiO2) or alumina (Al2O3). Mobile phase: polar solvent, like ethanol.

Stationary and mobile phases used in gas chromatography? Why do smaller molecules have a shorter retention time?

Stationary phase: powder, coated with oil, packed into or coated onto inside of long coiled capillary tube in oven. Mobile phase: inert gas, like N2/He Smaller molecules travel faster in inert gas.

What stationary and mobile phase are used in column chromatography?

Stationary phase: powder, like silica, Al2O3 or resin, packed in a column. Mobile phase: any polar solvent, like ethanol.

What are the steps in calculating relative atomic mass?

Step 1: For each peak multiply the relative isotopic abundance by the relative isotopic mass. Step 2: Add up these totals. Step 3: Divide by 100

Chelate Effect

Substitution of a unidentate ligand by a multidentateligand giving a more stable complex and an increase in entropy

Name the monosaccharides of which the following disaccharides are composed. Sucrose: monosaccharides ...............and .................... Lactose: monosaccharides .................and ................ (2)

Sucrose: Glucose and fructose Lactose: Glucose and galactose

Advantages of fermentation of Glucose to produce ethanol

Sugar is renewable, low technology level = cheap equipment

Standard Molar Enthalpy of Combustion

The Enthalpy Change when 1 mole of a substance is completely burned in excess oxygen under standard conditions with all reactants and products in their standard states. ∆Hc = ∑∆Hc(Reactants) - ∑∆Hc(Products)

Why might changing certain amino acids that are not part of the active site also prevent the enzyme from functioning? (3)

The changed amino acid may cause the hydrogen bonds to change; so the tertiary structure and hence the shape of the enzyme will change; so the active site may change shape causing the substrate to no longer fit

What is a conjugate base? What is a conjugate acid?

The conjugate base of an acid is formed when the acid donates a proton. The conjugate acid of a base is formed when the base accepts a proton.

Bond dissociation enthalpy

The enthalpy change when one mole of covalent bonds are broken in the gas phase

An enzyme catalyses only one reaction. Explain why. (2)

The enzyme has an active site; and only one specific substrate is complementary and fits the active site

What is the site of gas exchange in mammals? (1)

The epithelium of the alveoli

What is speciation? (1)

The evolution of new species from existing species

(Refer to June 2006 paper) Figure 1 shows a plant cell that was placed in a sucrose solution. Explain the appearance of the cell. (2)

The external solution has lower water potential; So water is lost from the cell by osmosis

The results of this investigation support the cohesion tension theory. Explain how. (2)

The movement starts in the branches; And creates tension, pulling water up from the trunk

Co-ordination number

The number of co-ordinate bonds formed to a central metal ion

What are 4 uses of esters, and why can they be used in these ways?

They smell sweet, so they're useful in: 1. Making perfumes 2. Sweeteners They are polar liquids, so polar organic compounds may dissolve in them and they've got low boiling points so evaporate easily from mixtures, so they are used as: 3. Solvents in glues and printing inks 4. They're used as plasticisers

Explain how the structure of this chamber causes this high pressure. (1)

Thick muscular walls

Describe and explain how water in the mesophyll cells passes out of the leaf. (3)

Through air spaces and out through stomata; by diffusion; down a diffusion gradient

Miner's lung is a disease caused by breathing in dust in coal mines. The dust causes the alveolar epithelium to become thicker. People with miner's lung have a lower concentration of oxygen in their blood than healthy people. Describe the path by which oxygen goes from an alveolus to the blood. (2)

Through alveolar epithelium; Through capillary epithelium

Why is TiO2 converted to TiCl4 before extraction?

TiCl4 is molecular (TiO2 is ionic), so it can be purified by fractional distillation (liquid at rt)

Why is it necessary for acetylcholine to be hydrolysed by acetylcholinesterase? (Sum)

To recycle the choline and ethanoic acid, to prevent acetylcholine from continuously generating a new action potential in the postsynaptic neurone.

Why is it necessary for acetylcholine to be hydrolysed by acetylcholinesterase? (2)

To recycle the choline and ethanoic acid; To prevent acetylcholine from continuously generating a new action potential in the postsynaptic neurone

Scientists investigated the effect of a drug called a proton pump inhibitor. The drug is given as a tablet to people who produce too much acid in their stomach. It binds to a carrier protein in the surface membrane of cells lining the stomach. This carrier protein usually moves hydrogen ions into the stomach by active transport. The scientists used two groups of people in their investigation. All the people produced too much acid in their stomach. People in group P were given the drug. Group Q was the control group. The graph shows the results. (Refer to June 2011 paper.) The scientists used a control group in this trial. Explain why. (1)

To see the effect of the drug

What does TMS stand for? Draw its displayed formula?

Trimethylsilane - its structural formula is Si(CH3)4, so you should know its displayed formula.

(Refer to June 2011 paper) A doctor measured the volume of air in the lungs of two people over a period of 7 seconds. Both people were resting. One person was healthy. The other had emphysema. The results are shown in the table. The two people were breathing out during the time shown. What evidence in the table supports this statement? (1)

Volume of air in lungs decreases

The scientists also measured the diameter of the trunk of the tree on which the twig had been growing. The diameter was less at 12.00 than it was at 03.00 hours. Explain why the diameter was less at 12.00 hours. (2)

Water is pulled up the trunk faster; The water column is under tension; And there is adhesion between water and xylem

A potometer measures the rate of water uptake rather than the rate of transpiration. Give two reasons why the potometer does not truly measure the rate of transpiration. (2)

Water used for support; Water used in photosynthesis

Water enters and leaves cells by osmosis. Figure 2 shows the water potential (ψ) in three palisade cells. (Cell A: -224kPa Cell B: -198kPa Cell C: -212kPa) Draw arrows on Figure 2 to show the net movement of water between the cells. Explain your answer. (2)

Water would move from B to A and B to C; Movement is from high water potential (Ψ) to a low water potential (Ψ)

Acid: red Alkali: yellow

What colour is methyl orange in acid and alkali?

A solution with a known concentration

What is a standard solution?

It's a major component of smog and it -Irritates people's eyes -Aggravates respiratory problems -Causes lung damage

What risks do ground-level ozone pose?

What is a neutralisation reaction?

When an acid reacts with an alkali and a salt and water is produced.

What is dynamic equilibrium?

When forward and backwards reaction occur at the same rate, so concentrations of product and reactant don't change

A Z-isomer

When priority groups on each carbon atom are on the same side of the C=C bond, what type of stereoisomer have you?

When does air leave the lungs? (1)

When the air pressure inside the lungs is greater than the air pressure of the atmosphere

What is the primary structure of a protein? (1)

The sequence of amino acids in a polypeptide chain which determines its properties and shape

What is the rate determining step/ slow step?

The step in the reaction mechanism that determines overall rate of reaction?

Several years later, scientists repeated their study on this population. They found that the frequency of the recessive allele had decreased. A statistical test showed that the difference between the two frequencies of the t allele was significant at the P = 0.05 level. Use the terms probability and chance to help explain what this means. (2)

There is a probability of 0.05; That difference in results are due to chance

The scientists carried out a statistical test to determine whether the correlation between the number of A. wattsi collected and the percentage of A. gingivinus infected was significant. They obtained a value for P of < 0.01. Use the terms probability and chance to help explain what this means. (2)

There is a probability of less than 1%; That results are due to chance

Explain how water enters xylem from the endodermis in the root and is then transported to the leaves. (6)

There is active transport of salts into the xylem; by the endodermis; which lowers the water potential in the xylem; Water evaporates from the leaves; and this creates cohesion between water molecules; This creates a continuous water column up the plant

The scientist reported that the difference between the number of people visiting Site R and the number visiting the other two sites differed significantly (p < 0.05). Use the words probability and chance to explain the meaning of differed significantly (p < 0.05). (2)

There was a probability of less than 0.05; that the difference was due to chance

Examples of Endothermic Reactions

Thermal Decomposition e.g. CaCO3 → CaO + CO2

What is thermal cracking?

Thermal cracking takes place at a high temperature of up to 1000'C and high pressures of up to 70 atm. It produces a lot of alkenes which are used to make valuable products like polymers.

Outside of an external magnetic field, why do the magnetic fields of nuclei cancel out? What happens to nuclei if you put them in an external magnetic field? Comparitively, what energy levels are nuclei aligned with an external magnetic field and those opposed to it in?

They are spinning in random directions. They will align with the field or opposed to it. The nuclei aligned with the external magnetic field are in a slightly lower energy level.

(Refer to exam q) Children with severe combined immunodeficiency disorder (SCID) cannot produce the many types of white blood cells that fight infections. This is because they do not have the functional gene to make the enzyme ADA. Some children with SCID have been treated with stem cells. Stem cells can divide and develop into any type of blood cell, including white blood cells. Using the information given, suggest and explain two reasons why stem cells were used in this treatment. (4)

They can divide to form new blood cells; So can replace existing faulty cells; Child's own cells; So little risk of rejection

Why don't catalysts affect rate of equilibrium? What do they do in terms of equilbrium?

They increase forward and reverse reaction rates by the same amount, so equilibrium position is unchanged. However, they allow equilibrium to be reached faster.

What is required for successful collisions of reacting particles?

They must collide in the right direction, with energy that is at least activation energy

There are large numbers of mitochondria in epithelial cells from the small intestine. Explain how these organelles help the cell to absorb the products of digestion. (2)

They release energy; Which is needed for active transport

What is required for condensation polymerisation to occur? How does it occur?

You need two different types of monomers, each with at least 2 functional groups in them. Each functional group reacts with a group on another monomer to form a link, creating polymers chains. Each time a link forms, a small molecule is lost (like water or methanol).

Formula of Al3+ metal aqua ion in soln

[Al(H2O)6]3+

Substance produced when Al3+ metal aqua ion reacts with NaOH in excess

[Al(OH)4]-

Substance made when [Co(H2O)6]2+ reacts with dil. NH3

[Co(H2O)4(OH)2] Blue Ppt

Substance made when [Co(H2O)6]2+ reacts with dil. NaOH

[Co(H2O)4(OH)2] Blue Ppt

Formula of Co2+ metal aqua ion

[Co(H2O)6]2+

Product when [Co(NH3)6]2+ is left to stand in air.

[Co(NH3)6]3+ Dark Brown Soln

Substance made when [Cr(H2O)6]3+ reacts with sodium carbonate. (Formula, colour, state)

[Cr(H2O)3(OH)3] Grey Green Ppt CO2 - effervescence

Substance made when [Cr(H2O)6]3+ reacts with dil. NH3 (Formula, colour, state)

[Cr(H2O)3(OH)3] Grey-Green, Ppt,

Substance made when [Cr(H2O)6]3+ reacts with dil. NaOH (Formula, colour, state)

[Cr(H2O)3(OH)3] Grey-Green, Ppt,

Formula of Cr3+ metal aqua ion in soln

[Cr(H2O)6]3+

Substance made when [Cr(H2O)6]3+ reacts with XS NH3 (Formula, colour, state)

[Cr(NH3)6]3+ Purple, Soln,

Substance made when [Cr(H2O)6]3+ reacts with XS NaOH (Formula, colour, state)

[Cr(OH)6]3- Green, Soln,

Substance made when [Cu(H20)6]2+ reacts with dil. Ammonia.

[Cu(H20)4(OH)2] blue ppt

Substance made when [Cu(H20)6]2+ reacts with dil. Sodium Hydroxide.

[Cu(H20)4(OH)2] blue ppt

Describe how rod cells act as transducers of energy. (2)

convert light energy to electrical energy; light energy causes change in rhodopsin

Racemic Mixture

equal mixture of enantiomers

Give two ways in which anaerobic respiration of glucose in yeast is different from anaerobic respiration of glucose in a muscle cell. (2)

ethanol formed by yeast, lactate formed by muscle cell; CO2 released by yeast but not by muscle cell

Fermentation of Glucose to produce ethanol

glucose 2 ethanol + 2 carbon dioxide

Insecticides are pesticides which kill insects. A low concentration of insecticide was sprayed on the leaves of rose plants to kill greenfly which were feeding on the plants. Ladybirds eat greenfly. One month after spraying, the concentration of insecticide in the tissues of ladybirds was found to be higher than the concentration sprayed on the rose plants. Explain why. (3)

greenflies take in small mass of insecticide from leaves; ladybirds eat large numbers of greenflies; insecticide cannot be broken down

Reactions of group 2 with oxygen

group 2 metals burn in oxygen

What is k, in terms of rates? Why does it increase with temperature?

k is rate constant. Rate is proportional to k, and when temperature increase, reaction rate increases; concentrations don't necessarily change, so k must rise.

Describe the part played by chlorophyll in photosynthesis. (3)

light energy absorbed by chlorophyll; raises energy level of electrons so that they are electrons emitted; ATP is formed

Give one dependent variable you could measure in order to determine the rate of photosynthesis in an aquatic plant. (1)

measure the volume of gas

When focusing, the shape of the lens in the eye changes. In an investigation, the maximum convexity of the lens was measured in people of different ages. Figure 4 shows the results. (decrease in convexity with age) Using information from Figure 4, explain how the change in the ability of the lens to become more convex affects the ability to focus clearly as people get older. (4)

more convex the lens, the greater the refraction; high refraction needed for near vision; lens becomes less elastic with age; hence difficulty in focusing on close objects

How would a value for ∆Hc, differ if it was measured with a reactant in the gaseous state compared to a reactant in the liquid state

more exothermic and negative, as heat is released when water vapour condenses, so less heat is needed to vapourise water. also molecules have more energy in the gaseous state.

The red seaweed lives under water at a depth of 2 metres. Suggest an advantage to the red seaweed of having other pigments in addition to chlorophyll a. (2)

more wavelengths absorbed; more efficient photosynthesis can occur at these depths

Acetylcholine is the neurotransmitter at neuromuscular junctions. Describe how the release of acetylcholine into a neuromuscular junction causes the cell membrane of a muscle fibre to depolarise. (3)

movement by diffusion; binding to receptors on post-synaptic membrane; causing sodium channels to open

Acetylcholine is the neurotransmitter at neuromuscular junctions. Describe how the release of acetylcholine into a neuromuscular junction causes the cell membrane of a muscle fibre to depolarise. (3)

movement of acetylcholine by diffusion; binding to receptors on post-synaptic membrane; causing sodium channels to open

Suggest an explanation for the percentage of energy lost in faeces for the herbivore being larger than that for the carnivore. (2)

much of food indigestible; indigestible material contains energy

One reason for the decrease in the death rate between 1851 and 1931 was the introduction of mass vaccination. Explain how vaccinating a large proportion of the population reduces the death rate. (2)

prevents spread of disease; any individual has lower chance of meeting infected individual

An investigation was carried out into the production of ATP by mitochondria. ADP, phosphate, excess substrate and oxygen were added to a suspension of isolated mitochondria. Suggest the substrate used for this investigation. (1)

pyruvate

Other substances are produced in the Krebs cycle in addition to the carbon compounds shown in the diagram. Name three of these other products. (3)

reduced NAD; reduced FAD; ATP

Shape of cisplatin

square planar

Explain what is meant by a climax community (1)

stable community with few changes to populations

ϴ in ∆Hϴ

standard conditions

Suggest and explain one advantage of this behaviour to the human body-louse. (2)

stays in favourable conditions; remains near on the host (near food source)

Giving one example, explain why homeostasis is important in mammals. (2)

temperature; optimum for enzymes

What features suit pioneer species to colonisation? (4)

the ability to fix nitrogen from the atmosphere as there are few nutrients; tolerance to extreme conditions; rapid germination of seeds; the ability to photosynthesise

The rectal temperatures of cows are recorded to monitor heat stress. This is a better measurement of core body temperature than measuring the temperature of the skin. Explain why. (2)

(Skin temperature) Fluctuates more; As more affected by environment

How can you reveal colourless chemical spots on TLC plate after chromatography? What do you count on a TLC plate to find out how many chemicals are present in a mixture? How do you find out what each chemical is?

- Fluorescent dye added to silica/alumina layer that glows when UV light is shone on it. - Seal TLC plate in a jar containing a couple of iodine crystals and iodine vapour, the locating agent, from the crystals stick to chemicals on the plate, making them show up as brown/purple spots. The number of spots that form on the plate. By calculating its Rf value, which is unique for each chemical at given conditions: Rf = (distance travelled by spot)/(distance travelled by solvent)

What is the functional group of the ester? Show the esterification of a general carboxylic acid and alcohol using displayed formulae, stating conditions required. What is another name for an esterification reaction? Why?

-COO- Refer to big sheets Condensation reaction - water is released

What are risks associated with using chlorine to treat water?

-Chlorine gas is very harmful if breathed in, as it irritates the respiratory system. Liquid chlorine on skin/ eyes causes severe chemical burns. -Water contains organic compounds from plant decomposition etc., with which chlorine reacts to form chlorinated hydrocarbons, which are carcinogenic.

Suggest why chloroethanoic acid is a stronger acid than ethanoic acid.

-Cl is (more electronegative so) withdraws electrons OR negative inductive effect of Cl -Weakens O―H bond OR O―H bond is more polar OR reduces negative charge on COO- OR stabilizes COO- (more)

What are buffers used for?

-In shampoos (pH 5.5), to stop hair's pH changing/ becoming too alkaline, keeping it smooth and shiny. -Biological washing powders, to keep the Ph right for the enzymes to work most efficiently. -In blood, it keeps pH close to 7.4, so tissues stay at the right pH

Suggest why nitrogen atom a, bonded to a benzene ring, is less likely to be protonated than nitrogen atom b, bonded to 3 alkyl groups.

-Lone pair on N labelled b more available / more able to be donated than lone pair on N labelled a -lp or electrons or electron density on N labelled a: delocalized into (benzene) ring -lp or electrons or electron density on N labelled b: methyl/alkyl groups electron releasing or donating or (positive) inductive effect or push electrons or electron density

Why is TMS used in N.M.R. spectroscopy?

-Only 1 peak on n.m.r. spectrum (all hydrogen and carbon atoms in a TMS molecule are in same environment) -This peak ios far from other peaks -It's volatile (so easily removed from sample)

-Why are amines Brønsted-Lowry bases? How do they show this? Are they strong or weak bases? -Draw the mechanism for this with a general primary amine. -What does the strength of the base depend on?

-They accept protons - the lone pair on the nitrogen atom forms a coordinate bond with a H+ ion. They're weak bases. -Refer to big sheet -The strength of the base depends on the availability of the lone pair - the more available it is, the easier it is to accept a proton and the stronger the base will be.

-In the reaction CH3COOCH(CH3)CH2CH3 → CH3CH(OH)CH2CH3 + CH3COONa, give reagents and conditions and name the type of reaction that occurs. -State how you could obtain a sample of the alcohol from the reaction mixture formed.

-Warm with dilute aqueous NaOH under reflux. -Fractional distillation.

Write an equation for the hydrolysis of a general polyester

-[-CO-R-CO-O-R'-O-]- + nH2O → n-[-CO-R-COOH + HO-R'-O-]-

Oxidation and reduction are the loss and gain of electrons respectively. Reducing agent: electron donor.

0

What is the oxidation state of a neutral compound?

0

What is the oxidation state of elements bonded to identical atoms, like O2 and H2?

0

What is the density of water?

1 g cm^-3 (or 1000 kg m^-3)

Copper Extraction using scrap iron

1) Copper ores are reacted with H2SO4 2) Iron reduces and therefore displaces copper solid from solution

Dynamic Equilibrium

1) Rate of forwards and backwards reactions are equal 2) concentrations of reactants and products stays constant

Properties of Transition Metals

1) Variable oxidation states 2) Catalytic action 3) Coloured compounds 4) Formation of complexes

What are the 3 factors considered in Industrial Equilibria?

1) Yield of Product 2) Rate of Reaction 3) Cost of maintaining reaction conditions

Possible main products when [Cr(H2O)6]3+ reacts with Zn or conc HCl. State the type of reaction and colours.

1) [Cr(H2O)6]2+ (aq) reduction, blue soln. 2) Cr2O7 (aq) reduction, orange soln.

What 4 types of bonding occur between enzymes and substrate?

1. Hydrogen bonding 2. Ionic bonding 3. Van der Waals forces of attraction 4. Dipole-dipole forces of attraction

Give an intermolecular force and a bond that act between different sections of an amino acid chain and explain how they arise, and which structures (primary, secondary and/or teriary) each stabilises. Why can factors like temperature and pH affect the shape of a protein?

1. Hydrogen bonding. Hydrogen bonds exist between polar gorups (like -OH and -NH2) in the chain, and stabilise both the secondary and tertiary structure of the protein. 2. Disulfide bonds. Amino acid cysteine contains a thiol group (-SH). Thiol groups on different cysteine residues can lose their hydrogen atoms and join together by forming a disulfide (sulfur-sulfur) single covalent bond. These disulfide bonds link together different parts of the protein chain, and help to stabilise the tertiary structure. They can affect hydrogen bonding and the formation of disulfide bonds and so can change the shape of proteins, as these determine the shape of the protein.

List and name the steps in the reaction of chlorine with methane to make chloromethane, naming any conditions. Identify unpaired electrons with. What happens next?

1. Initiation reactions: Cl2 → 2Cl. UV light is required 2. Propagation reactions: Cl. + CH4 → .CH3 + HCl .CH3 + Cl2 → CH3CL + Cl. 3. Termination reactions: .Cl + .CH3 → CH3Cl .CH3 + .CH3 → C2H6 .Cl + .Cl → Cl2 If chlorine's in excess, .Cl free radicals start attacking chloromethane, making di-, tri- and even tetrachloromethane.

What is Kw at 298K?

1.00 x 10^-14 mol^2dm^-6

Use the information in the table to calculate the size of the population of Mexico in 2008. Show your working. (2)

107,000,000/1000 x 20 = 2,140,000 births 107,000,000/1000 x 5 = 535,000 deaths 107,000,000 + 2,140,000 - 535,000 = 108,605,000

Explain one piece of evidence from the diagram which proves that the allele for Tay-Sachs disease is not on the X chromosome. (2)

11 is affected, 3 is not; If on X 11 would not receive the recessive allele on X chromosome from father

Draw the structure of the phosphate group What pentose sugar exists in nucleotides in DNA? Draw its structure What 4 bases exist in nucleotides in DNA?

11. Refer to big sheets 2-deoxyribose 12. Refer to big sheets Adenine (A), thymine (T), guanine (G) and cytosine (C)

Using shapes, display simply how the phosphate group, sugar and base in one nucleotide are bonded. How do nucleotides bond together to form DNA? DIsplay a section of the sugar-phosphate backbone using shapes.

13. Refer to big sheets The nucleotides bond together to form a polynucleotide chain: covalent bonds form between the phosphate group of one nucleotide and the sugar of another, forming the sugar-phosphate backbone of the chain. 14. Refer to big sheets

Draw the reversible reaction for the condensation polymerisation that forms the sugar-phosphate backbone of a DNA molecule What happens during this process?

15. Refer to big sheets A water molecule is lost and a covalent phosphodiester bond is formed (between the phosphate group in one molecule and the sugar in the other)

(Refer to Jan 2006 paper) Figure 1 shows a section through a palisade cell in a leaf as seen with a light microscope. The palisade cell has been magnified × 2000. Calculate the actual width of the cell, measured from A to B, in μm. Show your working. (2)

16; measured distance (31mm)/Mag

Draw the cisplatin complex. What is its shape? What is a use of cisplatin?

17. Refer to big sheets Square planar As an anti-cancer drug

Lactose, galactose and monosaccharide X are all reducing sugars. After the lactose has been broken down there is a higher concentration of reducing sugar. Explain why. (1)

2 sugars produced

Which nitro compounds is TNT?

2,4,6-trinitromethylbenzene

What is TNT's IUPAC name?

2,4,6-trinitromethylbenzene OR 2,4,6-trinitrotoluene

Name 52. on big sheets

2-aminopropane

Calculate the total volume of air breathed in and out per minute when the cyclist is cycling at 20kmh-1. Show your working. (2)

20 × 2.75 = 55 dm2

At room temperature, 2-aminobutanoic acid exists as a solid. Draw the structure of the species present in the solid form.

21. Refer to big sheets

HOCH2CH2CH2CH2COCl → (22. on big sheets) + HCl Draw the mechanism for this reaction

22. Refer to big sheets

PLA is the condensation polymer formed from lactic acid (CH3CH(OH)COOH). An intermediate in the production of PLA is a cyclic compound (C6H8O4) that is formed from two PLA molecules. Draw the structure of this cyclic compound.

24. Refer to big sheets

Name these molecules on big sheets:

25. Phenylamine 26. Phenyl ethanoate 27. 2-hydroxybenzoic acid 28. Phenylethene 29. Benzene-1,4-dicarboxylic acid 30. Methyl 3-nitrobenzoate 31. Benzaldehyde 32. Benzoic acid 33. Phenol 34. 2-bromophenol 35. 3-fluorotoluene OR 1-fluoro-3-methylbenzene 36. Nitrobenzene 37. 1-bromo-2-chlorobenzene 38. Phenylethanoic acid 39. Phenylethanone 40. 4-phenyl-2-butanone 41. Ethanedioyl chloride 42. Butanedioc acid

Blue tits are small birds that live in woods. An ecologist estimated the size of the blue tit population visiting gardens near a wood in November. • She trapped 28 blue tits. She marked all of these birds with small metal rings on their legs. • Two weeks later, she trapped another sample of blue tits. Of these birds, 18 were marked and 20 were not marked. Use the data to estimate the size of the blue tit population. Show your working. (2)

28 x 38/ 18 = 59

Calculate the value of P. (1)

3.74

A new power station is to be built which will emit a total of 3800 tonnes of carbon over 20 years. In order to balance the carbon emissions a pine forest will be planted to remove an equivalent amount over 20 years. Use the graph to work out the smallest area of forest that would be needed. Show your working. (2)

3800/180 = 20.65

A triglyceride molecule is formed by condensation. From how many molecules is this triglyceride formed? (1)

4

Seesaw, 102,87

4 bond pairs, 1 lone pair: name and bond angle(s)

Square planar, 90

4 bond pairs, 2 lone pairs: name and bond angle(s)

Tetrahedral, 109.5

4 bond pairs: name and bond angle(s)

What is the specific heat capacity of water?

4.18 J g^-1 K^-1

Draw the species formed by 4-methylphenylamine in concentrated HCl

44. Refer to big sheets

Hair length in cats is determined by a single gene with two alleles. The allele for long hair (h) is recessive. The allele for short hair (H) is dominant. Use the information in the table and the Hardy-Weinberg equation to estimate the percentage of cats in London that are heterozygous for hair length. Show your working. (2)

44.22;

Calculate the percentage of energy transferred from primary consumers to tertiary consumers. (Primary Consumers - 7079 Tertiary Consumers - 45) (1)

45/7079 x 100 = 0.636 %

Sixteen percent of the population of Europe is Rhesus negative. Use the Hardy-Weinberg equation to calculate the percentage of this population that yo would expect to be heterozygous for the Rhesus gene. Show your working. (3)

48(%); q2 = 16%; 2pq = heterozygotes

Write an equation for the reaction between dimethylamine and hydrochloric acid, naming the product.

48. Refer to big sheets Dimethylammonium chloride

At room temperature, the amino acid 2-aminobutanoic acid exists as a solid. Draw the structure of the species present in the solid amino acid.

49. Refer to big sheets

Draw benzene with its p orbitals

56. Refer to big sheets

Given the structure of the amino acid proline (57. on big sheets), draw the dipeptide formed from two proline molecules.

58. Refer to big sheets

Draw the structure of the acetal (C4H8O2) formed by the reaction of ethanal with ethane-1,2-diol.

59. Refer to big sheets

Octahedral, 90

6 bond pairs: name and bond angle(s)

Production of polymer PGA occurs via a cyclic compound. Two HOCH2COOH molecules react together to form the cyclic compound and two molecules of water. Draw the structure of this cyclic compound.

60. Refer to big sheets

Draw the displayed formula for 2-amino-3-methylbutanoic acid.

8. Refer to big sheets

pH

= - log [H^+]

pKa

= -log Ka

Equilibrium constant (Kc)

= [C]^c [D]^d / [A]^a [B]^b (where A and B are reactants and C and D are products)

Ionic product of water (Kw)

= [H^+] [OH^-]

Rate equation

= k [A]^m [B]^n

(Refer to exam q diagram) The diagram represents an enzyme molecule and three other molecules that could combine with it. Which molecule is the substrate for the enzyme? Give a reason for your answer. (1)

A because structure of A is complementary to that of the active site

Heterogeneous catalyst

A catalyst which is in a different physical state to the reactants.

Salt bridge

A connection between two half cells that ions can flow through , used to complete the circuit.

What is a stimulus? (1)

A detectable change in the internal or external environment of an organism that produces a response

Fuel cell

A device that converts the energy of a fuel into electricity through oxidation reaction.

What is a zwitterion? In terms of amino acids, where, figuratively, do zwitterions exist?

A dipolar ion, which has both a positive and negative charge in different parts of the molecule. Near the amino acid's isoelectric point.

What are giant ionic lattices?

A lattice is just a regular structure. Ionic crystals are giant lattices of ions. Different ionic compounds have different shaped structures but they're all still giant lattices.

Electrode potential

A list of electrode potential written in order from the most negative to positive.

What is a nucleophile?

A lone pair donor

Entropy

A measure of the amount of disorder in a system (e.g. the number of ways that particles can be arranged and the number of of ways that the energy can be shared out between particles).

Define a 'risk'. (1)

A measure of the probability that damage to health will occur as a result of a given hazard.

Cisplatin

A platinum containing complex ion with a square planar shape that can be used as an anti-cancer drug.

What sort of charge must an electrophile have in order to attack benzene? Why can some of these not attack benzene. How is this resolved? Give an example of what is used to resolve this.

A positive charge, but many aren't polarised enough. You can make an electrophile stronger by using a catalyst called a halogen carrier, like AlCl3.

Haemoglobin

A protein found in blood that helps to transport oxygen around the body.

What is a catalyst?

A substance that speeds up a chemical reaction by providing an alternative reaction route with a lower activation energy, while being chemically unchanged at the end.

What is a reducing sugar? (1)

A sugar that can donate electrons to another chemical

Explain how lack of light caused the amount of radioactively labelled glycerate 3-phosphate to rise. (2)

ATP and reduced NADP not formed; GP is not being used to form RuBP

Dead cells can no longer produce ATP. Soon after death, muscles contract, making the body stiff. From your knowledge of muscle contraction, explain why this happens. (3)

ATP attaches to myosin heads and detaches them from binding sites on the actin filament, making muscle relax; As no ATP is produced after death, none attaches to myosin heads; Remain attached to actin, leaving the muscle in a contracted state

ATP is better than either glucose or fatty acids as an immediate energy source for cell metabolism. Explain why. (2)

ATP energy released in a single reaction; ATP energy released in small quantities

Explain why oxygen is needed for the production of ATP on the cristae of the mitochondrion. (4)

ATP formed as electrons pass along transport chain; oxygen is final electron acceptor; electrons cannot be passed along electron transport chain if no O2 to accept them; forms H2O;

What is the role of the small intestine? (1)

Absorbs the products of digestion into the bloodstream

What are monoprotic acids? What can you assume [H+] is for a strong monoprotic acid?

Acids whose molecules each produce 1 proton upon dissociation. For a strong monoprotic acid, you can assume [H+] is strong acid concentration.

Amphoteric

Act as acids and bases

Describe the two types of protein filaments. (2)

Actin - thinner and consists of two strands twisted around one another Myosin - thicker and consists of long rod-shaped fibres with bulbous heads

By which process do root hairs take up nitrate ions? (1)

Active transport

What are the general formulae of aldehydes, ketones and carboxylic acids?

Aldehydes & ketones: CnH2nO Carboxylic acids: CnH2n+1COOH

An increase in nitrate concentration in the water entering the lake could affect algae and fish in the lake. Explain how. (3)

Algal bloom occurs; Algae block light so plants die; Decomposers break down dead plant materials and use up oxygen; Fish die due to lack of oxygen

Alcohol + dehydrating agent

Alkenes are produced, conc. H2SO4/ H3PO4 is used, warm under reflux, acid catalysed elimination

Name monosaccharide X. (1)

Alpha glucose

When RFI is calculated, low values are negative. Explain why they are negative. (1)

Amount of food taken in less than expected.

Healthy people have amylase in their blood. This does not cause any harmful effects in the body. Explain why. (2)

Amylase is specific to starch; No starch is in human blood

Amylase and maltase are involved in the digestion of starch in the small intestine. Where are these enzymes produced and what are the product of the reaction they catalyse? (2)

Amylase: pancreas, produces maltose; Maltase: epithelium of small intestine, produces glucose

What type of reaction is nitrification? (1)

An oxidation reaction

Explain what is meant by the term phenotype. (2)

Appearance due to genotype; and due to environment

Which blood vessels do the ventricles pump blood into? (1)

Arteries

The scientists randomly divided the volunteers into two groups. Explain why they divided them randomly. (1)

Avoids bias

Colour of Cr3+ metal aqua solution

Blue-Green

What is the formula of glucose? (1)

C6H12O6

What are totipotent cells? (1)

Cells which can develop into any other cell of the organism

Describe how the Pacinian acts as a transducer of energy. (1)

Converts mechanical energy to electrical energy

Given that the standard enthalpy of hydrogenation of cyclohexane is -120kJmol^-1, calculate that for cyclohexa-1,3,5-triene and estimate that for cyclohexa-1,3-diene. Explain these

Cyclohexa-1,3,5-triene: 3*-120kJmol^-1 = -360kJmol^-1 Cyclohexa-1,3-diene: -239 to -121 -Proximity - for 1,3 C=C bonds are close together -Delocalisation - for 1,3 some delocalisation OR some overlap of electrons, π clouds or p orbitals -Some extra stability for the 1,3- isomer

(Refer to exam q) The diagram shows the banding pattern observed in part of a relaxed muscle fibril. Describe what causes the different bands seen in the muscle fibril. (2)

Darker band has both types of filament; Light band has only actin filaments

The pigs were allowed to eat as much food as they wanted. How could this have decreased the reliability of any conclusions drawn from the investigation? (2)

Different growth rates; Not due to temperature

Sample vaporised and electron gun fires high energy electrons at it, which knock off, generally, 1 electron from each particle, making them 1+ ions

Electron impact

State, in terms of its bonding, why benzene is more stable than cyclohexa-1,3,5-triene.

Electrons delocalised in benzene, but not in cyclohexa-1,3,5-triene.

ΔE

Energy difference between d-orbitals

Complete the equation to show how net production is calculated from the energy in ingested food. P = (1)

F - E - R

The enthalpy change on removing 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions

First ionisation energy

Describe how NAD is regenerated in anaerobic respiration in yeast cells. (1)

Formed when reduced NAD is used to convert pyruvate to ethanol

v

Frequency of light absorbed

Explain why the scientist did not use glucose as the respiratory substrate. (2)

Glucose is used during glycolysis; Glycolysis occurs in the cytoplasm, not in mitochondria

One day, the man did not eat a midday meal. Suggest one reason why his blood glucose concentration did not fall dangerously low even though he had injected himself with the mixture of insulin before breakfast. (1)

Glycogen converted to glucose

Give the IUPAC name of CH3COCH2CH2COCH3

Hexane-2,5-dione

Give one reason why a reaction is very slow at room temperature

High Ea so few molecules have E>Ea, and low rate of successful collisions

Name two chemical mediators and state the effects they each have on blood vessels. (Sum)

Histamine and prostaglandins - both cause dilation of small arteries and arterioles and increased permeability of capillaries.

What type of solvents are samples dissolved in before hydrogen-1 NMR spectroscopy, and why? Give 2 example of solvents used, and why they are used.

Hydrogen-free solvents, which contain no hydrogen-1 atoms, otherwise the solvent would show up on the spectrum and confuse results. 1. Deuterated solvents - they contain only deuterium atoms, not hydrogen-1 atoms; deuterium nuclei contain 2 nucleons, so have no spin and aren't affected by an external magnetic field, so deuterated solvents produced no peaks on a hydrogen-1 NMR spectrum. 2. CCl4 (tetrachloromethane) - it doesn't contain hydrogen-1 atoms either.

The enzyme sucrase catalyses the breakdown of sucrose into monosaccharides. What type of reaction is this breakdown? (1)

Hydrolysis

The equation shows the breakdown of lactose by the enzyme lactase. lactase lactose + water -----------> galactose + monosaccharide X Name the type of reaction catalysed by the enzyme lactase. (1)

Hydrolysis

Explain why maintaining a constant blood glucose concentration is important in mammals. (3)

Important in maintaining constant water potential; Changes may cause cells to shrink or expand due to water entering or leaving cells; Reliable source of glucose for respiration by cells

Suggest two reasons for the increase in asthma sufferers. (2)

Increase in air pollution; Increase in stress

What are isotopes?

Isotopes of an element are atoms with the same number of protons but different numbers of neutrons

Explain how the cuticle reduces water loss. (1)

It is waxy so waterproof

What risks do ground-level ozone pose?

It's a major component of smog and it -Irritates people's eyes -Aggravates respiratory problems -Causes lung damage

Why is ethanol used in many mechanisms?

It's a polar solvent and helps reactant to mix - unlike water, it isn't broken into OH- ions and H+ ions, so it doesn't partake in the reaction.

Why is reacting ethanoyl chloride with methanol oft a preferred way of making esters?

It's an irreversible reaction and much faster than using carboxylic acids.

Suggest an explanation for birth rate increasing (1)

Lack of contraception

An arteriole is described as an organ. Explain why. (1)

Made of different tissues

Use figures 4 and 5 to explain why most detail is perceived when rays of light strike the part of the retina labelled Q. (2)

Maximum number of cones at Q; Each cone has connection with one neurone

Why do synaptic knobs possess many mitochondria and large amounts of endoplasmic reticulum? (2)

Mitochondria provides ATP for synthesis of proteins and neurotransmitters; Endoplasmic reticulum synthesises proteins and neurotransmitters

Name two structures present in eukaryotic cells that are not present in the cells of prokaryotes. (2)

Mitochondria; Nuclear envelope

Reagents required to form CrO4^2-

NaOH or H2O2

Disproportionation of Halogen + Sodium Hydroxide

NaX, NaXO, H2O are produced, mixture is used to bleach and kill bacteria (disinfectant)

The correlation coefficient that they obtained had a negative value. What does a negative value indicate about these data? (1)

Negative correlation between feather mites and breeding success

Describe the basic events in the transmission of a nerve impulse from one neurone to another. (Sum)

Neurotransmitter is released from vesicles in the presynaptic neurone into the synaptic cleft when an action potential reaches the synaptic knob. The neurotransmitter diffuses across the synapse to receptor molecules on the postsynaptic neurone to which it binds, thereby setting up a new action potential.

Examples of exothermic reactions

Neutralisation, Fuel Combustion, Carbohydrate Oxidation (used in respiration)

Name the process by which some bacteria oxidise ammonia to nitrate. (1)

Nitrification

Substance made when [Fe(H2O)6]3+ reacts with sodium hydroxide in excess.

No Change

Optical Isomerism

Occurs where there are three bidentate ligands in an octahedral complex. They basically look like mirror images of each other.

Half cell

One half of an electrochemical cell.

In an investigation into the effect of pH on the time taken by amylase to hydrolyse starch, you were given buffers with a pH range from 5 to 8. Suggest why. (2)

Outside this range reaction is slow; Optimum pH is within this range

Suggest the chemical process that would cause a sample of propan-2-ol to become contaminated with propanone

Oxidation

What is oxidation? What is reduction? What do reducing and oxidising agents do? What is a redox reaction?

Oxidation and reduction are the loss and gain of electrons respectively. Reducing agent: electron donor. Oxidising agent: electron acceptor. A redox reaction is one in which oxidation and reduction occur simultaneously.

Substance made when [Co(H2O)6]2+ reacts with XS NH3

Pale Brown Sol [Co(NH3)6]2+

Name 45. on big sheets

Phenylammonium ion

Suggest why one piece of fungus has no clear area round it. (1)

Piece of fungus might have died

Explain, in terms of pressure, why the semilunar valves open. (1)

Pressure is greater in ventricle than artery

How can genes be prevented from expressing themselves? (2)

Preventing transcription and hence the production of mRNA; Breaking down mRNA before its genetic code can be translated

What is the role of the atrioventricular valves? (1)

Prevents backflow of blood into the atria when the ventricles contract

Explain why the scientists used isotonic solution during the process. (2)

Prevents osmosis; So the mitochondria is not damaged

What haloalkanes tend towards different mechanisms

Primary Haloalkanes - substitutions Secondary Haloalkanes - Both Tertiary Haloalkanes - Elimination

What are primary, secondary and tertiary alcohols?

Primary: 1 alkyl group attached to carbon atom to which -OH group is bonded Secondary: 2 alkyl groups Tertiary: 3 alkyl groups

Give one function of the cell wall of a bacterial cell. (1)

Provides protection

How is Type II diabetes controlled? (2)

Regulating intake of carbohydrate in the diet; Relative to amount of exercise taken

Why does an action potential pass along a myelinated neurone faster than an unmyelinated one? (4)

Saltatory conduction; Myelin sheath acts as an insulator; Prevents action potentials from forming; Action potentials jump between nodes of Ranvier

Speciation is far less frequent in the reformed Amazonian forest. Suggest one reason for this. (1)

Same environmental factors

Advantages of Recycling Metals

Saves Resources, Less waste, less landfill, less air pollution, saves energy,

Scientists investigated the response of the roots of pea seedlings to gravity. They took three samples of seedlings, A, B, and C, and placed them so that their roots were growing horizontally. The root tips of each sample had been given different treatments. After a set time, the scientists recorded whether the roots of the seedlings had grown upwards or downwards and the amount of curvature. The table shows the treatment they gave to each sample and their results. Treatment Direction of Growth Curvature/degrees None (a) Downwards 60 Tip removed(b) Continues horizontal 0 Upper half of Downwards 30 tip removed(c) The pea seedlings were kept in the dark after each treatment. Explain why this was necessary.(1)

Seedlings respond to light

Increasing temperature

Shifts the equilibrium in the endothermic direction

Weak Base

Slightly Dissociate

What type of isomerism is optical isomerism?

Stereoisomerism

Oestrogen is a hormone that affects transcription. It forms a complex with a receptor in the cytoplasm of target cells. Explain how an activated oestrogen receptor affects the target cell. (2)

Stimulates RNA polymerase; Increases transcription

Explain the change in the rate of water movement through the xylem between 06.00 and 12.00 hours. (2)

Stomata open; So transpiration increases

Where exactly in a cell is the enzyme Rubisco found? (1)

Stroma of chloroplasts

Name three structures in the skin that are involved with thermoregulation in mammals. (3)

Sweat glands; Hair erector muscle; Arterioles/capillaries

What is the function of the RER? (1)

Synthesises proteins

On the graph 1 mark with a T a point on the curve where the potato cells are turgid; 2 mark with a W a point on the curve where the potato cells have the same water potential as the sucrose solution. (2)

T anywhere to left of 0.3 M; W at 0.3 M;

Name 43. on big sheets

Tetraethylammonium chloride`

What is the secondary structure of a protein? (1)

The 3D shape of the polypeptide chain which forms as a result of hydrogen bonding; a coil known as an a-helix.

What is electronegativity?

The ability to attract the bonding electrons in a covalent bond. It is meausred on the Pauling scale. The higher the number the better the ability to attract the bonding electrons.

Molecular Formula

The actual number of atoms of each element in a molecule

Energy gap ΔE

The amount of energy needed for an electron to transfer to a higher orbital.

What is relative molecular mass?

The average mass of an entity compared to one twelfth of the mass of an atom of carbon 12.

What is the tertiary structure of a protein? (1)

The bending and twisting of the polypeptide helix into a compact structure. This is maintained by disulfide, ionic and hydrogen bonds.

What is hydrolysis? (1)

The breakdown of large, insoluble molecules into smaller soluble ones by the addition of water to the bonds that hold the molecules together

Name a tissue that prevents the movement of water through the apoplast pathway. (1)

The casparian strip of the endodermis

Autocatalyst / Autocatalysed

The catalyst is a reaction product

How does fractional distillation work?

The crude oil is vaporised at about 350 degrees Celsius and it rises up through the trays. The largest hydrocarbons don't vapourise at all, because their boiling points are too high. As the crude oil vapour goes up the fractional column, it gets cooler creating a temperature gradient. As the alkanes get bigger their boiling point increases so each fraction condenses at a different temperature. The hydrocarbons with the lowest boiling points don't condense, they're drawn off as gases at the top of the column.

What is a sarcomere? (1)

The distance between adjacent Z-lines

Enthalpy of Combustion

The enthalpy change when 1 mol of a compound Is completely burned in oxygen Under standard conditions, all substances in standard states

In kinetics, what does e^(-Ea/(RT)) represent?

The fraction of collision with at least activation energy.

What does the Hardy-Weinberg principle predict about the frequency of the t allele after another 10 generations? (1)

The frequency remains the same

In ClCH2COCl, why does AlCl3 remove the rightmost chlorine atom but not the leftmost one?

The leftmost C-Cl bond is too strong, but the rightmost one is relatively weak, as the oxygen atom (more electronegative than chlorine) draws electrons away from the C-Cl bond and towards itself.

What is the climax community determined by? (1)

The main abiotic factor

What is homeostasis? (2)

The maintenance of a constant internal environment; allows cells to function normally despite external changes

What is molar mass?

The mass of one mole of something, the same as relative molecular mass but the units are g mol-1

What is activation energy?

The minimum amount of kinetic energy particles need to successfully collide and react

Activation Energy

The minimum energy required for a chemical reaction to take place Ea

In chromatography, what is the mobile phase? In chromatography, what is the stationary phase? What basic principle is used in all chromatography?

The mobile phase is the phase in which the molecules being identified can move. This is always a liquid or a gas. The stationary phase is the phase in which the molecules being identified can't move. This must be a solid, or a liquid on a solid support. 1. Mobile phase moves through/over stationary phase. 2. Distance each substance moves up plate depends on its solubility in the mobile phase and its retention by stationary phase. 3. Components more soluble in mobile phase will move further up plate. 4. Differences in solubility and retention by stationary phase separate out different substances.

What is the molecular formula?

The molecular formula gives the actual numbers of atoms in a molecule.

The heart muscle is myogenic. What does this mean? (1)

The muscle contraction originates from within the heart muscle itself

Why are bronchioles made of muscle? (2)

The muscle contracts which allows bronchioles to constrict; to control the flow of air in and out of the alveoli

What is the NO2^+ ion called?

The nitronium ion

What is ventilation rate? (1)

The number of breaths taken in one minute

In terms of the magnetic fields, what does NMR measure? What partly shields a nucleus from the effects of an external magnetic field? If a carbon atom is bonded to an oxygen atom, what will happen to the amount of electron shielding around the carbon atom's nucleus? Why?

The overall absorption of energy by the nuclei in the external magnetic field. Surrounding electrons and any other atoms or groups around the nucleus. It'll decrease - oxygen is more electronegative

What is the refractory period? (2)

The period after an action potential when inward movement of sodium ions is prevented because the sodium channels are closed; preventing a further action potential from being generated

Describe how changes in the environment lead to increased biodiversity during succession. (5)

The pioneer species photosynthesise and fix nitrogen; These die and form a soil with nutrients; Further colonisers can survive in this soil as environment is less hostile; More habitats and food sources are available; Increased biodiversity

What is half neutralisation?

The point at which half the acid has been neautralised. If the acid is HX, at this point, [HX]=[X-] and pH=pKa, as Ka = [H+][A-]/[HA]

What is DNA? What is DNA made up of? What do these constituents act as? What 3 things are nucleotides made up of?

The polymer that contains all of an organism's genetic information. Nucleotides, which act as the monomers. A phosphate group A pentose sugar A base

What does the Hardy-Weinberg principle predict? (3)

The proportion of alleles of a particular gene; Will stay constant from one generation to the next; Providing there is no mutation

What happens during the vaporisation stage of mass spectrometry?

The sample is turned into a gas using an electrical heater in a vacuum.

Overall order of reaction

The sum of the powers to which the concentration terms are raised in the rate equation

What is the theoretical yield?

The theoretical yield is the mass of the product that should be formed in a chemical reaction. It assumes no chemicals are 'lost' in the process.

Heat

The total energy of all particles present in a given substance. Heat is dependent on the amount of substance

What is Hess's law?

The total enthalpy change for a chemical reaction is independent of the route taken

What is pulmonary ventilation? (1)

The total volume of air that is moved into the lungs during one minute

What is tidal volume? (1)

The volume of air normally taken in at each breath when the body is at rest

What is cardiac output? (1)

The volume of blood pumped by one ventricle of the heart in one minute

What is the stroke volume? (1)

The volume of blood pumped out at each beat

What does a diprotic acid/ strong base graph look like? Write equations for the reactions occuring at the first and second end points for ethanedioic acid and hydroxide ions?

There are 2 end points. First end point: HOOCCOOH + OH- → HOOCCOO- + H2O Second end point: HOOCCOO- + OH- → -OOCCOO- + H2O

What is meant by the all-or-nothing principle? (4)

There is a certain level of stimulus that triggers an action potential; This threshold value must be exceeded to produce an action potential; At any level above this threshold, a stimulus will trigger an action potential of the same size; Regardless of the size of the stimulus

(Refer to Jan 2010 paper) A zoologist investigated the relationship between body mass and rate of oxygen uptake in four species of mammal. The results are shown in the graph. The scale for plotting body mass is a logarithmic scale. Explain why a logarithmic scale was used to plot body mass. (1)

There is a large range of values so used so that they can fit on graph

What are unburnt hydrocarbons.

These are emitted when engines don't burn all of the fuel molecules. These hydrocarbons react with nitrogen oxides in the presence of sunlight to form ground level ozone (O3) which is a major component of smog

Give and explain one advantage and disadvantage of polyalkenes.

They are addition polymers and are made of non-polar carbon chains, making them unreactive and chemically inert. Advantage: a polystyrene (polyalkene) cup won't react with your coffee or any contents Disadvantage: polyalkenes are non-biodegradable, as they can't be attacked by nucleophiles and broken down via hydrolysis

State the relationship between two chiral molecules with the same structural formula.

They are non-superimposable mirror images

Very small organisms do not have specialised gas exchange systems. Explain how they obtain sufficient oxygen for respiration. (2)

They have a large surface area to volume ratio; and a short diffusion distance

Enzymes are catalysts. What is meant by this? (1)

They speed up the rate of a reaction without undergoing permanent changes or being used up themselves.

(Refer to exam q) The photograph shows part of the gill of a fish as seen through a light microscope. It is magnified × 400. Explain how the structure of the gill makes oxygen uptake efficient. (2)

Thin epithelium; creates a short diffusion pathway

What is the Atomic (proton) number?

This is the number of protons in the nucleus of an atom and is used to identify an element

What is the positive inductive effect?

This is when alkyl groups in a carbocation feed electrons toward the positive charge, stabilising it.

describe Thomson's model of the atom.

Thomson's model of the atom was like a 'plum pudding' with a positively charged pudding (solid sphere) that contained negatively charged particles (electrons).

Who are at greater risk of contracting pulmonary tuberculosis? (4)

Those in close contact with infected individuals over long time periods; Long-term care facilities e.g. hospitals, care homes, prisons; Those with reduced immunity; The very young and very old

How do you calculate pulmonary ventilation? (1)

Tidal volume x Ventilation rate

Retention Time

Time taken for a particular substance to pass through a chromatography column

What metal is exacted using an active metal?

Titanium (TiO2) Temperature: 1st Stage ~900 2nd stage ~500

The biologists needed to find a way of distinguishing between the hairs of the three species of shrew. They collected hairs from shrews of each species. For each species, they selected hairs at random and made different measurements. Explain why the biologists selected the hairs at random. (1)

To avoid bias

Why do intercostal muscles allow the ribs to move? (2)

To enable the lungs to be ventilated by a tidal stream of air; thereby ensuring that the air within them is constantly replenished

Why was it important to have a control group in this investigation? (1)

To ensure that results are not due to some other substance in the chocolate

A student found the number of stomata per cm2 on the lower surface of a daffodil leaf. He removed a small, thin piece of lower epidermis and mounted it on a microscope slide. He examined the slide using an optical microscope. Explain why it was important that the piece of the epidermis that the student removed was thin. (2)

To obtain fewer layers of cells; So that light that can pass through

The student cut the shoot and put it into the potometer under water. Explain why. (1)

To prevent air entering

A group of scientists homogenised pancreatic tissue before carrying out cell fractionation to isolate organelle G. Explain why the scientists homogenised the tissue. (1)

To release the cell contents

Why is the liver tissue homogenised? (1)

To release the cell contents

Explain why the scientists filtered the resulting suspension. (1)

To remove cell debris

Why are haloalkanes not used any more?

Toxicity, detrimental effects on the atmosphere

A newspaper headline used the information in the graph to claim 'Alcohol is good for you.' Evaluate this claim. (3)

True because studies show decreased risk up to 3 drinks per day; False because all studies show an increased risk above 5 drinks per day; Also another factor may be influencing these results

Biofuels are produced by a variety of different companies. The scientists who developed the method of calculating NLPs are funded by the government's environmental agency. Suggest two advantages of this method being developed by these scientists. (2)

Trustworthy - no bias; Non-profit making

Use of poly(propene)

Utensils, Containers, Rope, Carpet Fibre, Stiff

In a titration, which titre volumes aren't considered anomalous?

Values that are within 0.1cm^3 of each other

Use information from Figure 1 to complete the table below to show whether the valves are open or closed at (i) 0.2 seconds (ii) 0.6 seconds between the right atrium and right ventricle, and between the right ventricle and pulmonary artery. (2)

Valve between right atrium and right ventricle: (i) closed (ii) open; Valve between right ventricle and pulmonary artery: (i) open (ii) closed

What is the strongest type of intermolecular forces of attraction between hydrogen sulfide molecules? Why aren't other forces present, if they aren't?

Van der Waals There aren't permanent dipole-dipole forces between H2S molecules as the difference in electronegativity between S and H atoms (2.58 compared to 2.2, respectively) is too small for there to be a "permanent" dipole within a H2S molecule.

What sources of error only exist in combustion calorimetry?

Vaporisation of volatile fuels, incomplete combustion

Changes in ecosystems can lead to speciation. In Southern California 10 000 years ago a number of interconnecting lakes contained a single species of pupfish. Increasing temperatures caused evaporation and the formation of separate, smaller lakes and streams. This led to the formation of a number of different species of pupfish. Explain how these different species evolved. (5)

Variation due to mutation; Different selection pressures; Selection for advantageous allele; Selected organisms survive and reproduce; Leads to change in allele frequency

The units in the table allowed the scientists to compare the oxygen consumptions of different iguanas. Explain how. (1)

Variation in mass taken into account

(Refer to exam q) Figure 1 shows a diagram of part of a muscle myofibril. Name the protein present in the filaments labelled W and X. (1)

W: myosin X: actin

Describe and explain four ways in which the structure of a capillary adapts it for the exchange of substances between blood and the surrounding tissue. (4)

Wall one cell thick, reduces diffusion distance; Flattened cells, reduced diffusion distance; Narrow lumen, reduces flow rate so more time for diffusion; Small diameter, creates a large surface area to volume ratio

Micrographs of lung tissue taken from people with emphysema show large air spaces compared with lung tissue from healthy people. Explain why. (1)

Walls of alveoli break down

How is the release of toxic gases in the burning of polymers reduced?

Waste gases from the combustion are passed through scrubbers which can neutralise gases like HCl by allowing them to reach with a base.

Industrial Alkene Hydration to form alcohols

Water +conc. H3PO4 catalyst, 1 step reaction, no waste products (high atom economy), high temperatures and pressures 300-600 degrees and 70 atm Seperation of products is easier and cheaper

What is a weak Brønsted-Lowry acid/base? Give examples

Weak acid: dissociate only very slightly in water, producing few protons. Ethanoic acid Weak base: only slightly ionise in water. NH3

1. Weak van der Waals forces of attraction between graphite layers allow them to slide over each other, so graphite feels slippery 2. There's 1 delocalised electron for each carbon atom, which is able to move through graphite carrying charge, so graphite conducts electricity 3. Layers are relatively far apart due to weak van der Waals forces between them, so graphite has a low density 4. There are many strong covalent bonds between the carbon atoms in graphite, which take lots of energy to break, so its melting point is high 5. Graphite is insoluble in any solvent, as covalent bonds in it are too many and strong to break

What are 5 properties of graphite? Why?

Halogenoalkane molecules in which all hydrogen atoms are replaced by chlorine and fluorine atoms

What are chlorofluorocarbons?

Molecules which contain carbon and hydrogen atoms only

What are hydrocarbons?

Acid: colourless Alkali: pink

What colour is phenolphthalein in acid and alkali?

Conditions: -Presence of a zeolite catalyst (hydrated aluminosilicate) -Slight pressure -High temperature (450°C) Products: -Aromatic hydrocarbons -Motor fuels Using a catalyst cuts costs, as it speeds up the reaction, saving time (time is money) and the reaction can be done at a low pressure and a lower temperature

What conditions are required for catalytic cracking, and what are the products? What are advantages of using a catalyst?

Conditions: -High temperature (up to 1000°C) -High pressure (up to 70 atm) Products: -Lots of alkenes Use: -To make plastics and other polymers

What conditions are required for thermal cracking, and what are the products and their uses?

It can enter the atmosphere and react with rain water to form sulfuric acid, contributing to acid rain. Acid rain destroys trees and vegetation and corrodes buildings and statues and kills fish in lakes.

What danger does sulfur dioxide have?

Atoms with significantly different electronegativities

What do polar bonds exist between?

A shared pair of electrons between two atoms

What is a covalent bond?

A species with an unpaired electron, which makes them very reactive.

What is a free radical? What makes them so reactive?

Reactive part of the molecule, which gives it most of its chemical properties.

What is a functional group?

An electrostatic force of attraction between a positive metal ion and a delocalised electron in a metal

What is a metallic bond?

They were used as coolant gas in fridges, as solvents and as propellants in aerosols CFCs' advantages can't outweigh environmental problems they cause (ozone decomposition) HFC (hydrofluorocarbons, without chlorine atoms) and hydrocarbons are used instead

What were CFCs once used for? Why are they now banned? What is used instead?

CnHn2+2

What's the general formula of an alkane?

Unidente

When a ligand can form only one coordinate bond in a complex ion.

Autocatalysis

When a reaction is catalysed by one of the products.

What is summation? (3)

When action potentials produce insufficient amounts of neurotransmitter to exceed the threshold value and trigger a new action potential, summation can occur; Spatial summation: a number of presynaptic neurones together release enough neurotransmitter to trigger an action potential; Temporal summation: a single presynaptic neurone releases neurotransmitter many times over a short period

When is landfill used to deal with plastic waste? Why is there a need to reduce landfill as much as possible?

When the waste plastic is difficult to separate from other waste, not in sufficient quantities to make separation financially worthwhile or too difficult to recycle. More and more plastic waste is being generated each year.

What is a dipole?

When there is a large difference in electronegativity in a polar bond so there is a large difference in charge between the two atoms caused by a shift in electron density in the bond.

What is a neuromuscular junction? (1)

Where a motor neurone meets a skeletal muscle fibre

Fluorine, oxygen or nitrogen, bonded to at least one hydrogen atom. F, O and N have high electronegativities, making their bonds with hydrogen atoms very polar.

Which 3 atoms can create hydrogen bonds? What must they be bonded to? Why are these atoms suitable?

(Refer to June 2010 paper) The table shows the frequencies of some alleles in the population of cats in three cities. White cats are deaf. Would the Hardy-Weinberg principle hold true for white cats? Explain your answer.

White cats unlikely to survive; Will not pass on allele for deafness to next generation

The further north, the greater the risk of snow and the more white snow geese there are. Use this information to explain how natural selection might have accounted for the effect of latitude on the percentage of white snow geese. (3)

White geese better camouflaged further north due to snow; Resulting in greater survival and reproductive success of the white snow geese

Water molecules are polar - the partially negative oxygen atoms attract cations and the anions attract the partially postive hydrogen atoms

Why are ionic compounds soluble in water?

Layers of metal ions slide over each other easily. Metallic bonds reform.

Why are pure metals malleable? Why doesn't the strength of a metal change when you bend it?

Electron is to be removed from more positive ion each time, with less repulsion between remaining electrons

Why are successive ionisation energies generally higher?

The 2 polar C=O bonds are arranged symmetrically, so they cancel out each other's polarity

Why aren't carbon dioxide molecules polar?

Electron is now taken from 3p orbital containing 2 electrons, between which there's electron repulsion that makes the electron easier to remove, in S, overriding increased nuclear charge. It is removed from a singly filled 3p orbital in P, in which there is no electron repulsion.

Why does first IE decrease between P and S?

Nitrogenase also catalyses reactions involving other substances. Explain what this suggests about the shapes of the molecules of these other substances. (2)

Will have complementary shape to active site; Forms enzyme-substrate complex

The efficiency of conversion of food to biomass is lower at 0 oC than it is at 20 oC. Suggest an explanation for the lower efficiency. (2)

Will lose more heat; So more food used in respiration

Give two characteristic features of stem cells. (2)

Will replace themselves; Undifferentiated

The inhaler which the person used contained a substance that dilates bronchioles. Use this information to explain why curve A is different from curve B. (More air breathed out in curve B) (2)

Without inhaler narrower bronchioles; Less air is able to pass through

What is the general ionisation equation?

X(g) => X+ = e-

What other observation may you see when NaI reacts with concentrated H2SO4?

Yellow solid (S)

Were the changes produced by hyperthermia significant? Give reasons for your answer. You should use the P values in your answer. (2)

Yes for temperature and oxygen consumption; Because P value is equal to or less than 0.05

Are condensation polymers biodegradable? If so, why?

Yes. They have polar bonds in their chains, which are open to attack by nucleophiles, so they can be broken down by hydrolysis, by water.

Why is Zn not a transition metal?

Zn can only form a +2 ion. In this ion the Zn2+ has a complete d orbital and so does not meet the criteria of having an incomplete d orbital in one of its compounds.

Structure of Tollen's Reagent

[Ag(NH3)2]+

Substance produced when Al3+ metal aqua ion reacts with Sodium carbonate

[Al(H2O)3(OH)3] White Ppt

Substance produced when Al3+ metal aqua ion reacts with dilute NH3

[Al(H2O)3(OH)3] White Ppt

Substance produced when Al3+ metal aqua ion reacts with dilute NaOH

[Al(H2O)3(OH)3] White Ppt

Substance made when [Fe(H2O)6]3+ reacts with dil ammonia

[Fe(H2O)3(OH)3] Brown ppt

Substance made when [Fe(H2O)6]3+ reacts with dil. sodium hydroxide

[Fe(H2O)3(OH)3] Brown ppt

How do you find proton concentration from pH?

[H+] = 10^-pH

Buffer equation

[H+] = Ka [acid] / [salt]

Acid dissociation constant of a weak acid (Ka)

[H^+] [X^-] / [HX]

How does the hormone glucagon regulate blood glucose concentration? (5)

a cells of islets of Langerhans in the pancreas detect fall in blood glucose level; Secrete glucagon into blood plasma; Glucagon binds with receptors on cell-surface membranes of liver cells; Liver cells activate enzyme that converts glycogen to glucose; Increase conversion of amino acids and glycerol into glucose

Co-ordinate bond

a covalent bond in which both electrons are donated by one atom

What is a trimer?

a polymer comprising three monomer units.

At first the waste heap had no plants growing on it. Some of the first plants to colonise it were small herbaceous plants. Explain one way in which colonisation by herbaceous plants could change the physical environment. (2)

accumulation of decomposed matter; increase in mineral ions in soil

The insecticide DFP combines with the active site of the enzyme acetylcholinesterase. Explain why the muscles stay contracted until the insecticide is lost from the neuromuscular junction. (2)

acetylcholinesterase is unable to breakdown acetylcholine; acetylcholine still available to depolarise the membrane

Acetylcholine is a neurotransmitter which binds to postsynaptic membranes and stimulates the production of nerve impulses. GABA is another neurotransmitter. It is produced by certain neurones in the brain and spinal cord. GABA binds to postsynaptic membranes and inhibits the production of nerve impulses. The diagram shows a synapse involving three neurones. Describe the sequence of events leading to the release of acetylcholine and its binding to the postsynaptic membrane. (4)

action potential arrives; calcium ions enter synaptic knob; vesicles fuse with membrane; acetylcholine diffuses across synaptic cleft

Explain two advantages and one disadvantage of an inorganic fertiliser such as sodium nitrate compared with an organic fertiliser such as manure. (3)

advantages: easy to apply; can supply specific needs; disadvantages: leads to eutrophication

Explain why converting pyruvate to ethanol is important in allowing the continued production of ATP in anaerobic respiration. (2)

allows NAD to be recycled; so that glycolysis can proceed

Explain the importance of reflex actions. (3)

automatic adjustments to changes in environment; preventing injury; helpful for escaping from predators

Explain why the spotted knapweed plants were never completely eliminated when using biological control (2)

because biological control never eats all plants; as weeds diminish so do control agents

What information is required in order to calculate the growth rate of a population? (2)

birth rate and death rate; emigration and immigration

Substance made when [Cu(H20)6]2+ reacts with conc. Ammonia.

blue ppt redissolves [Cu(NH3)4(H20)2]2+

The diameter of the pupil is reduced in bright light. Describe the part played by the autonomic nervous system in reducing the diameter. (3)

bright light stimulates impulses from eye to brain; parasympathetic system; stimulates contraction of circular muscles

Magnesium + Oxygen

burns with a white flame to produce a white solid with high melting point (ionic). Magnesium also reacts slowly with oxygen even without the flame, so a thin layer of MgO is always on Mg ribbon and needs to be cleaned off by emery paper

Describe how NADP is reduced in the light-dependent reaction of photosynthesis. (2)

by electrons; that leave the chlorophyll molecule

Using your knowledge of muscle contraction, explain the difference in the results between B and C. (2)

calcium ions remove tropomyosin; to allow binding of myosin heads and actin, increasing ATPase activity

Cross-channel swimmers may suffer from muscle fatigue during which the contraction mechanism is disrupted. One factor thought to contribute to muscle fatigue is a decrease in the availability of calcium ions within muscle fibres. Explain how a decrease in the availability of calcium ions could disrupt the contraction mechanism in muscles. (3)

cannot move tropomyosin; from binding sites on actin; myosin heads do not bind

Explain how the growth of the forest results in a decrease in the carbon content of the atmosphere. (2)

carbon dioxide taken in as a result of photosynthesis; carbon is incorporated into compounds in the trees

Nervous transmission is delayed at synapses. Explain why. (2)

chemical rather than electrical; Process of transmission takes time because of transmitter diffusion

Give an example of a reagent which could be used to show that the reducing ability of bromide ions is different from that of chloride ions

conc. H2SO4

Most of the UK populations of natterjack toads are found on sand dune systems. The communities of plants and animals on such systems usually change over time as a result of succession. Explain how the natterjack conservation recommendations could affect succession in a sand dune system. (3)

conservation measures tends to stop this; keep communities the same; adding lime stops pH change

Describe one role of the stroma in the process of photosynthesis. (1)

contains enzymes for carbon dioxide fixation

Describe one role of the grana in the process of photosynthesis. (1)

contains light absorbing pigments

Adrenaline binds to receptors in the plasma membranes of liver cells. Explain how this causes the blood glucose concentration to increase. (2)

cyclic AMP produced; So glycogenolysis occurs

Explain what is meant by a significant difference. (1)

difference is due to factors other than chance

Each cycle requires hydrolysis of one molecule of ATP and moves one actin filament 40nm. During contraction of a muscle sarcomere, a single actin filament moves 0.6μm. Calculate how many molecules of ATP are required to produce this movement. (2)

distance single actin filament moves divided by distance moved using 1 ATP; 15 ATP

Disadvantages of Electrolysis

electricity costs, low purity achieved

Describe how ATP is produced by the electron transport chain. (3)

electrons pass through a series of carriers; energy released in transfer; energy used to make ATP;

Use your knowledge of energy transfer to explain the difference in biomass between hares and their predators. (2)

energy loss between trophic levels; Only some of energy in hare biomass converted to predator biomass, e.g. energy used by predators to catch hares

Describe how you would collect a random sample of a population. (2)

generation of random co-ordinates; use of 10 or more quadrats

Disadvantages of using Ethene to produce ethanol

high tech equipment needed, non-renewable, high energy costs to high pressure

Give one reason to explain why the rate of recycling of carbon would be greater in summer than in winter. (1)

higher temperatures, increasing enzyme activity

Heather plants are small shrubs. Heather plants are the dominant species in the climax community of some moorlands. The structure and shape of a heather plant changes as it ages. This results in changes in the species composition of the community. A large area of moorland was burnt leaving bare ground. The table shows four stages of succession in this area. Explain why the number of other plant species decreases between 4 and 12 years after burning. (2)

increased interspecific competition; for light

The correlation between vegetation cover and soil moisture content was tested statistically. These two factors were found to be positively correlated, and p < 0.05. Explain what this result means. (2)

increasing vegetation cover is related to increasing moisture content; the correlation was not due to chance

Cytochrome c is one of the components of the electron transport chain. Give the precise location of cytochrome c in the cell. (2)

inner membrane of mitochondrion

Name the type of competition occurring between mesquite and grass. (1)

interspecific

What is the Arrhenius equation?

k = Ae^(-Ea/RT)

Suggest suitable units for the measurement of energy transfer in pyramids of energy. (1)

kJ m-2 yr -1

Suggest suitable units to represent biomass in pyramids. (1)

kg m-²

Describe two problems caused by the use of non-specific insecticides. (2)

kill useful insects, such as pollinators; kill predators of pest leading to later increase in pest numbers

(Refer to exam q) The human body-louse is an insect which lives and feeds on the surface of the skin. A louse was placed in a chamber, half of which was kept at 35 °C and half at 30 °C. The diagram shows the pattern of movement of the louse. Name the type of behavioural response shown by the body-louse in this investigation. Give evidence for your answer. (2)

kinesis; due to its random movements

Suggest how plants should be chosen at each sampling site to avoid bias and to be representative.(2)

large sample; random coordinates should be generated

Some plants in a dry, hot desert have a uniform distribution and are widely spaced. Suggest how this type of distribution is an advantage to the plants. (2)

less competition; for water

Advantages of Copper Extraction using scrap iron

less energy used, lower grade ores (more sustainable), lower quality scrap iron (not wasted)

Explain the rise in the amount of ribulose bisphosphate after the carbon dioxide concentration is reduced. (1)

less used to combine with carbon dioxide

Suggest a genetic explanation for the difference in life expectancy of females and males. (3)

males have XY, females XX; males produce testosterone; which causes males to take more risks and be more aggressive

Explain how a resting potential is maintained in a neurone. (4)

membrane less permeable to sodium ions; sodium ions actively transported out; sodium ion carrier proteins; inside of axon is negative compared to outside

Give two differences between a cholinergic synapse and a neuromuscular junction. (2)

neurone to neurone and neurone to muscle; action potential in neurone and no action potential in muscle

Half equivalence

pH = pKa

Explain why the mass of crop produced stays the same in both fields when more than 40 kg of fertiliser is added. (2)

plants already have enough nitrate; another factor is limiting growth

What is shift measured in?

ppm

Explain why small mammals have a higher rate of respiration than larger mammals. (2)

smaller mammals have a larger SA:V ratio; so lose more heat

Cl2 uses

to kill bacteria, health benefits outweigh toxicity

What metal is exacted using hydrogen?

tungsten: WO3 Temp >900

What are the 5 stages in mass spectrometery?

vaporisation, ionisation, acceleration, deflection, and detection

Suggest an explanation for the difference in sensitivity of rod cells to the white and green spots after 30 minutes. (1)

white has wavelengths to which rhodopsin not sensitive;

Conditions for the fermentation of Glucose

yeast anaerobic conditions - air would cause ethanol to be oxidised to produce ethanoic acid 30-40 degrees (optimum of 38) - if too low slow reaction, if too high, enzyme denaturation

Synapses are unidirectional. Explain how acetylcholine contributes to a synapse being unidirectional. (2)

Acetylcholine released from presynaptic side; Diffusion is from higher concentration to lower concentration

What's this functional group: -COOCO- (23. on big sheets)?

Acid anhydride

What is a Lewis acid/base?

Acid: an electron pair acceptor Base: an electron pair donor

What is a Brønsted-Lowry acid/base?

Acid: proton donor Base: proton acceptor

What are acidic buffers made of? What are basic buffers made of?

Acidic buffers: a weak acid and one of its salts Basic buffers: a weak base and one of its salts

If we cut across a myofibril at certain points, we see only thick myosin filaments. Cut at a different point we see only thin actin filaments. At yet other points we see both types of filament. Explain why (2)

Actin and myosin filaments lie side by side in a myofibril; and overlap at the edges where they meet

Describe one way that the lock and key model is different from the induced fit model. (1)

Active site is a fixed shape in the lock and key model

Induced fit and lock and key are two models used to explain the action of enzymes. Describe the induced fit model of enzyme action. (2)

Active site is not complementary to the substrate; It changes shape to fit the substrate

What's an asymmetric carbon atom?

A carbon atom bonded to 4 different groups

Homogeneos catalyst

A catalyst which is in the same physical state as the reactants.

How does pH affect enzyme action? (3)

A change in pH alters the charges on the amino acids that make up the active site; so the substrate can no longer become attached to the active site; so an enzyme-substrate complex cannot be formed

What is meant by conservation? (1)

A method of maintaining ecosystems and the living organisms that occupy them

Purely ionic model of a lattice

A model which assumes that all ions in a lattice are spherical and have their charges evenly distributed around them.

What is a molecular formula?

A molecular formula is the actual number of atoms of each element in a molecule,

Feasible reaction

A reaction which has a a free energy change that is less than or equal to zero and will happen spontaneously.

Buffer

A solution which maintains pH despite the addition of acid or base

Metal-aqua complex ion

A species formed when transition metal ions dissolve in water.The water molecules form coordinate bonds with the metal ions.

What is meant by a pioneer species? (1)

A species that can colonoise an inhospitable environment

Explain why a statistical test was necessary in analysing the results for the common shrew. Use the terms chance and probability in your answer. (2)

A statistical test determines the probability of results being due to chance; Enables null hypothesis to be accepted or rejected

Describe how an action potential is produced in an axon. (6)

A stimulus causes a temporary reversal of charge and inside of axon becomes positive (depolarisation); Energy of stimulus causes some sodium channels to open; So sodium diffuses into axon; Once an action potential of +40mV has been established, channels close and there is no more influx of sodium; Potassium channels open and potassium ions diffuse out, causing repolarisation of axon; Axon becomes more negative than usual, so potassium gates close and sodium-potassium pump again actively transports sodium ions out and potassium ions in

What is the structural formula?

A structural formula shows the atoms carbon by carbon, with the attached hydrogens and functional groups.

Le Chatelier's principle

A system at equilibrium reacts to oppose a change in conditions

Write a simple equation to show how ATP is synthesised from ADP. (1)

ADP + Pi -----> ATP

Explain why the concentration of oxygen and amount of ADP fell during the investigation. (2)

ADP and phosphate forms ATP; oxygen used to form water

One group of organelles was placed in a hypotonic solution. Describe and explain the effect on the organelle of placing it in the hypotonic solution. (4)

Outer membrane breaks down; Solution has a higher water potential; Water moves into organelle by osmosis; Organelle swells and bursts

The behaviour of the desert iguanas keeps their body temperatures within a narrow range. Explain how. (2)

Outside optimum temperature moves between sun and shade; Warm up or cool down

Different wavelengths of light are used to illuminate a tube containing a suspension of photosynthetic algal cells. The percentage of light absorbed and the rate of photosynthesis are measured using the apparatus shown in Figure 5. (Oxygen meter attached to tube containing suspension of algal cells with light meter measuring amount of light transmitted through tube) What measurements should be taken to determine the rate of photosynthesis? (1)

Oxygen produced per unit time

Sodium azide is a substance that inhibits the electron transport chain in respiration. The student repeated the investigation but added sodium azide after 4 hours. Suggest and explain how the addition of sodium azide would affect oxygen uptake and the production of ethanol.(3)

Oxygen uptake decreases; Oxygen is final electron acceptor; More ethanol produced

(Refer to BYA6 June 2003 paper) Figure 2 shows the effect of impulses from neurones P and Q on the production of an action potential in neurone B. Each effect is a type of summation. Use information in Figure 2 to explain the two types. (2)

P - impulses from same neurone many times over a short period - temporal summation; Q - impulses from different neurones at the same time - spatial summation

The diagram shows the transfer of energy through a cow. The figures are in kJ × 106 year-1. A = energy absorbed from the gut C = energy consumed in food F = energy lost in faeces P = energy used in production of new tissue R = energy lost by respiration U = energy lost in urine Complete the following equation for the energy used in the production of new tissue. Use only the letters C, F, R and U. (1)

P = C - R - U- F

A breeder crossed a black male cat with a black female cat on a number of occasions. The female cat produced 8 black kittens and 4 white kittens. Explain the evidence that the allele for white fur is recessive. (1)

Parents are heterozygous

What is chemical shift measured in? What is TMS's shift value?

Parts per million (ppm) relative to TMS. 0 ppm

Identify the three factors that can cause disease. (3)

Pathogens, lifestyle and genetic factors.

Lysozyme is an enzyme. A molecule of lysozyme is made up of 129 amino acid molecules joined together. In the formation of its active site, the two amino acids that are at positions 35 and 52 in the amino acid sequence need to be close together. Name the bonds that join amino acids in the primary structure. (1)

Peptide bonds

The ecologists repeated the investigation but sprayed chemical pesticide on the strawberry plants after 10 weeks. After 16 weeks no predatory mites were found but the population of two-spotted mites had risen significantly. Suggest an explanation for the rise in the two-spotted mite population. (2)

Pesticide kills predatory mites; Two-spotted mite reproduces

The use of organochlorine pesticides has been severely restricted, due partly to their bioaccumulation in food webs. They have been replaced by organophosphate pesticides, which do not accumulate in food webs. Explain how bioaccumulation of some pesticides can occur in food webs. (2)

Pesticide not biodegradable; Stored in tissues

Explain how farming practices increase the productivity of agricultural crops. (5)

Pesticides prevent consumption of crop; Herbicides remove competition; Selective breeding of crops; Greenhouses enhance light; Ploughing improves drainage

Name a tissue that transports solutes from the leaves. (1)

Phloem

(Refer to Jan 2013 paper) The enzyme tyrosine kinase (TK) is found in human cells. TK can exist in a non-functional and a functional form. The functional form of TK is only produced when a phosphate group is added to TK. Addition of a phosphate group to the non-functional form of TK leads to production of the functional form of TK. Explain how. (2)

Phosphate changes shape of TK; Active site becomes complementary to substrate

Why is DNA acidic?

Phosphate groups which form the backbone of the DNA chains have P-O-H groups, which can donate H+ ion: POH → PO- + H+

Name two substances for which there would be a net movement into the mitochondrion. (2)

Pyruvate; ADP

Scientists used a line transect to find the distribution of three species of Ranunculus (buttercup) in a field. Describe how you would use a transect to obtain data on the distribution of the Ranunculus species. (2)

Quadrat placed along line at regular intervals; Count number per m2

Draw the general structure for an ether.

R-O-R', where R and R' are alkyl groups.

What is a kinesis? (2)

Random movements in response to a stimulus; From an unfavourable environment to a favourable one

Describe a practical technique which you could use to find the mean population density of daisies on a lawn. (3)

Random sampling method; Using many quadrats in each area; Counting daisies and dividing by area;

Why does the structure of muscle allow it to perform its function of contraction efficiently? (1)

Separate muscle cells are fused into muscle fibres; so there are no points of weakness

Explain how a change in the primary structure of a globular protein may result in a different three-dimensional structure. (3)

Sequence of amino acids changes; So tertiary structure changes; So bonds form in different places

What are the features of a control mechanism? (5)

Set point (desired level/norm); Receptor (detects deviation from set point and informs controller); Controller (coordinates information from receptor to effector); Effector (brings about changes to return system to set point); Feedback loop (informs receptor of changes done by effector)

Rod cells allow us to see objects in dim lights. Explain how the connections of rod cells to neurones in the retina make this possible. (3)

Several rods have connections with one neurone; Generator potentials exceed the threshold; Individual generator potentials do not exceed the threshold

Describe and explain the symptoms of emphysema. (4)

Shortness of breath; due to difficulty in exhaling air due to loss of elasticity in alveoli; which reduces diffusion gradient and decreases the rate of diffusion of oxygen into the blood; also due to smaller alveolar surface area which reduces diffusion of oxygen into the blood

Maxwell- Boltzmann Distribution

Shows the spread of energies that molecules of gas or liquid have at a particular temperature

The biologists used hair tubes to find the abundance of shrews along the edges of some fields. They also used traps that caught shrews without harming them. They selected areas where all three species of shrew were present. • They put sets of hair tubes at 5 m intervals along the edges of the fields. They inspected the tubes one week later and recorded the number of sets of tubes that contained shrew hairs. They called this the hair tube index. • At each site where they used hair tubes, they set traps immediately after using the hair tubes. They recorded the number of different shrews caught in these traps. The research team found the hair tube index. Explain why they could not use the hair tubes to find the total number of shrews present. (1)

Shrews may enter without leaving hair or one shrew may leave many hairs

Which is more polar: silica and Al2O3, or ethanol?

Silica and Al2O3?

(Refer to June 2010 paper) Some breast tumours are stimulated to grow by oestrogen. Tamoxifen is used to treat these breast tumours. In the liver, tamoxifen is converted into an active substance called endoxifen. Figure 2 shows a molecule of oestrogen and a molecule of endoxifen. Use Figure 2 to suggest how endoxifen reduces the growth rate of these breast tumours. (2)

Similar shape to oestrogen; Prevents oestrogen binding

Folic acid is a substance required by bacteria for cell growth. Bacteria produce folic acid by the following reaction. enzyme para-aminobenzoic ----------------------> folic acid acid (PABA) The diagram shows the structure of a molecule of PABA. It also shows the structure of a molecule of a drug called sulfanilamide, which can be used to treat bacterial infections. (Diagram shows similar shapes) Sulfanilamide prevents bacteria producing folic acid. Use the diagram and your knowledge of enzymes to explain how sulfanilamide prevents bacteria producing folic acid. (3)

Similar structure to PABA and is complementary to the active site of the enzyme; It binds to active site of enzyme; So less PABA is able to bind

(Refer to BYB1 Jan 2003 paper) Describe the similarities and differences between the structure of Trichonympha and the structure of all prokaryotic cells. (5)

Similarities: Both have membranes; Both have ribosomes; Differences - Trichonympha has nucleus; Trichonympha has mitochondria; Trichonympha has no cell wall

What is the melting point of a covalent bond?

Simple covalent bonds have low melting points because the weak forces between molecules are easily broken.

What is the electrical conductivity like in a covalent bond?

Simple covalent compounds don't conduct electricity because there are no free ions to carry the charge.

Many different substances enter and leave a cell by crossing its cell surface membrane. Describe how substances can cross a cell surface membrane. (5)

Simple or facilitated diffusion from high to low concentration; Large molecules go through proteins; Water moves by osmosis from high water potential to low water potential; Active transport and facilitated diffusion involves carrier proteins; Active transport requires energy

2nd ionisation enthalpy

The enthalpy change when one mole of gaseous +1 ions loses one electron per ion to form one mole of gaseous +2 ions

2nd electron affinity enthalpy

The enthalpy change when one mole of gaseous 1- ions gains one electron per ion to form one mole of gaseous 2- ions

1st electron affinity enthalpy

The enthalpy change when one mole of gaseous atoms gains one electron per atom to form one mole of gaseous 1- ions

Enthalpy of atomisation

The enthalpy change when one mole of gaseous atoms is formed from an element in its standard state

1st ionisation enthalpy

The enthalpy change when one mole of gaseous atoms loses one electron per atom to form one mole of gaseous +1 ions

Enthalpy of combustion

The enthalpy change when one mole of substance goes under complete combustion in oxygen, with all substances in their standard states

What is the second ionisation energy?

The second ionisation energy is the energy needed to remove an electron from each ion in 1 mole of gaseous 1+ ions.

What is the primary structure of a protein? Describe the secondary structure of a protein? Describe the tertiary structure of a protein?

The sequence of amino acids in the chain that makes up the protein (the polypeptide chain) The peptide links can form hydrogen bonds with each other, meaning the chain isn't a straight line. The shape of the chain is its secondary structure. The most common secondary structure is a spiral called an alpha (α) helix. The beta (β) helix is another common type of secondary structure, which is a layer of protein folded like a concertina. The chain of amino acids is often coiled and folded in a characteristic way that identifies the protein. Extra bonds can form between different parts of the polypeptide chain, giving the protein a kind of 3-d shape.

In column chromatography, what's the eluent?

The solvent in the mobile phase.

Unidentate ligands

ligands which form one co-ordinate bond to a metal ion

Bidentate ligands

ligands which form two co-ordinate bonds to a metal ion.

Where monoculture takes place on a large scale, farmers often remove hedges. Explain two benefits to the farmer of removing hedges. (2)

more space for crop; easier to use machines

Figure 2 shows the cut ends of the protein filaments when the myofibril was cut at position Y. Figure 3 shows the protein filaments when the myofibril was cut at the same distance from a Z line at a different stage of contraction. Explain why the pattern of protein filaments differs in Figure 2 and Figure 3. (2)

myofibril is contracting in Figure 3 and relaxing in Figure 2; figure 3 shows movement of actin fibres between myosin fibres

After death, cross bridges between actin and myosin remain firmly bound resulting in rigor mortis. Using information in the diagram, explain what causes the cross bridges to remain firmly bound. (2)

no ATP produced; ATP required for separation of actin and myosin

Why is a viral infection more likely to destroy a complete batch of plants grown by plant tissue culture than a batch of plants grown from seeds? (1)

no genetic variation

What is meant by the refractory period? (1)

no new nerve impulse be produced in this time

Explain why heavy metal ions may accumulate in food webs. (2)

not biodegradable; taken up by producers and thus passed up food chains

What is the equation linking the number of moles to concentration and volume?

number of moles = concentration x volume (in dm3)

Explain how chemical control leads to the changes in the number of spotted knapweed plants from March to June. (1)

number of plants drops because of reapplication, then rises because insecticide washed away

(Refer to exam q) The diagram shows the change in the charge across the surface membrane of a non-myelinated axon when an action potential is produced. (Inside of axon goes from being negative to positive) Describe how the change shown in the diagram occurs when an action potential is produced.(2)

sodium channels open; sodium ions enter axon

Explain how movements of these sodium and potassium ions are involved in producing the action potential. (2)

sodium ions diffuse in; causing depolarisation

Explain how the removal of hedges near the lake would increase the impact of fertilisers on the aquatic ecosystem. (2)

soil + fertilisers blown into lake; fewer nutrients taken up by the hedges

Describe how the temperature of the soil around developing tubers could be measured throughout their growing period. (2)

soil thermometer; consistent depth of readings

Explain why food chains rarely have more than five trophic levels. (2)

some energy lost at each stage in the food chain; little energy left at the top of food chain

Explain why the spotted knapweed plants were never completely eliminated when using chemical control (2)

some plants are not sprayed; plant may be resistant to spray

Reduced NADP produced during the light-dependent reactions of photosynthesis is used in the light-independent reactions. Explain how. (2)

the photolysis of water produces hydrogen protons which reduce NADP; the reduced NADP reduces glycerate 3-phosphate to TP

What information does the bar representing standard deviation give about a sample? (1)

the spread of values around the mean height of the plant

What is Atom economy?

Atom economy is a measure of the proportion of reactant atoms that become part of the desired product (rather than by-products) in the balanced chemical equation.

Ligand

Atom/Ion with a lone pair that forms co-ordinate bonds to metal.

What is a charge cloud?

Bonding pairs and lone pairs of electrons exist as charge clouds. A charge cloud is an area where you have a really big chance of finding an electron pair.

Explain what is meant by codominant alleles. (1)

Both alleles are expressed in the phenotype

Describe the relationship between metabolic heat generation and evaporative heat loss shown in the graphs. (2)

Both increase proportionally up to 25 degrees; Then heat generation increases faster

Colour of Bromine and Bromide

Br2 → Red liquid, brown dense poisonous fumes Br- → ions Yellow solution

There is an increase in the activity of the enzyme ATPase during muscle contraction. An investigation into muscle contraction involved measuring the activity of ATPase in solutions containing ATP, myosin and different muscle components. The table shows the results. (Refer to exam q) Explain the importance of ATPase during muscle contraction. (2)

Breaks down ATP, yielding energy; Used to break actomyosin bridges

What is a species? (2)

Breed among themselves; To produce fertile offspring

Lighter 1+ ions travel faster through drift region so reach detector sooner than heavier 1+ ions. They pick up electrons from the detector, creating current, which is proportional to relative isotopic abundance. Mass spectrum produced on a screen

Detection

What's the general formula of an alkane?

CnHn2+2

(Refer to exam q) Mitochondria were isolated from liver tissue using differential centrifugation. The tissue was chopped in cold, isotonic buffer solution. A buffer solution maintains a constant pH. The first stages in the procedure are shown in the diagram. (Tissue chopped in cold isotonic buffer solution then homogenised then centrifuged at low speed for 10 minutes.) The tissue was chopped in cold, isotonic buffer solution. Explain the reason for using (i) a cold solution (ii) an isotonic solution (iii) a buffer solution (3)

Cold - reduced enzyme action; Isotonic - prevents damage to the cells by osmosis; Buffer - prevents damage to enzymes

Disdvantages of Recycling Metals

Collecting, Sorting and Transporting costs

Succession occurs in natural ecosystems. Describe and explain how succession occurs. (5)

Colonisation by pioneer species; Change in environment caused by organisms present; Enables other species to survive; Change in biodiversity; Less hostile environment; Climax community

Explain how light energy is used to generate ATP in plants. (3)

Excites electrons from chlorophyll; Electrons passes down carriers; Energy released during transfer

Disadvantages of using Hydrogen for extraction

Explosive, difficult to store, expensive

You could use curve A to find the total volume of air that this person could breathe out in one complete breath. Describe how. (2)

Extend graph; Read off where it flattens

Give one function of the molecule labelled Y. (1)

Extrinsic protein for cell recognition

Oxidising Strength of Group 7

Decreases down the group, due to reduced nuclear pull, weaker oxidising agent is displaced from solution by a stronger halide

Electronegativity down Group 7

Decreases, as atomic radii increases down the group, increasing number of shells, so reduced nuclear pull

(Refer to BYA6 June 2003 paper) Figure 1 shows two motor neurones, A and B. It also shows the synapses of neurone B with three other neurones, P, Q and R. An action potential is produced in neurone A. Describe how this action potential passes along the neurone. (3)

Depolarisation of axon membrane causes local currents to be set up; Na+ gates open in adjoining region and sodium ions enter; Adjoining region depolarises

Explain how the release of FSH is controlled by negative feedback. (2)

FSH stimulates release of oestrogen; Oestrogen (initially) inhibits FSH production

(Refer to June 2013 paper) Scientists investigated the response of lateral roots to gravity. Lateral roots grow from the side of main roots. The diagrams show four stages, A to D, in the growth of a lateral root and typical cells from the tip of the lateral root in each stage. All of the cells are drawn with the bottom of the cell towards the bottom of the page. Describe three changes in the root tip cells between stages A and D. (3)

Formation of vacuole; Formation of starch grains; Movement of grains towards bottom of cell

Human skeletal muscle can respire both aerobically and anaerobically. Describe what happens to pyruvate in anaerobic conditions and explain why anaerobic respiration is advantageous to human skeletal muscle. (4)

Forms lactate; Can still form ATP when oxygen in short supply; NAD is needed to take up the hydrogen newly produced from glycolysis; NAD can be re-used to oxidise more respiratory substrate; which allows glycolysis to continue

Describe the role of structure A in inspiration. (3)

It contracts; Pulling ribs upwards and outwards; Increasing volume of thorax

Describe the function of the Golgi apparatus. (2)

It packages, synthesises and modifies proteins

How is a presynaptic neurone adapted for the manufacture of neurotransmitter? (Sum)

It possesses many mitochondria and large amounts of endoplasmic reticulum.

In what pH does methyl orange change colour, and what is the colour change? What about phenolphthalein indicator?

Methyl orange: (red) 3.1 → 4.4 (yellow) Phenolphthalein: (colourless) 8.3 → 10 (pink)

Write an equation for the reaction of magnesium with cold water - how fast is this reaction and why? Write an equation for the reaction of magnesium with steam.

Mg(s) + 2H2O(l) → Mg(OH)2 +H2(g) This reaction is slow - magnesium has high first and second ionisation energies, so is unreactive Mg(s) + H2O(g) → MgO(s) +H2(g)

Multidentate

Forms two or more co-ordinate bonds

Colour of Fe2+ metal aqua ion in soln

Green

Colour of F2

Pale yellow Gas

Mass of 1 atom of an isotope divided by 1/12 the mass of a carbon-12 atom

Relative isotopic mass

What are the main forms an ore takes

an oxide or a sulphide

Standard conditions

298K 100kPa All ion solutions at concentration 1 moldm

What are standard conditions?

298K, 100kPa

What reaction occurs in a catalytic converter? What are 2 metals are used in a catalytic converter?

2CO + 2NO → 2CO2 + N2 Metals: platinum and rhodium

Products when [Cr(OH)6]3- reacts with hydrogen peroxide.

2CrO4^2- +2OH- + 8H2O

Write the equation for the reaction of sodium bromide with concentrated sulfuric acid - observations? Is this a redox reaction?

2NaBr(s) + 2H2SO4(aq) → Na2SO4(s) + Br2(g) + SO2(g) + 2H2O(l) Orange fumes (Br2) and choking fumes (SO2) This is a redox reaction

What conditions are used in the equilibrium reaction of ethene with steam to form ethanol? Why aren't lower temperatures used even though the foward reaction is exothermic? Why aren't higher pressures used, even though number of moles decreases in the forward reaction?

60-70 atm pressure 300C temperature Phosphoric acid catalyst Lower temperatures than 300C aren't used, otherwise reaction rate would be too slow. Higher pressures than 60-70 atm aren't used, otherwise they'd be expensive (in terms of cost of equipment) to contain.

(Refer to Jan 2012 paper) Figure 1 shows the volume of blood in a man's right ventricle at different times during one cardiac cycle. Use the data in Figure 1 to calculate the man's heart rate. (1)

60/0.7 = 86

Use the information in the table to calculate the heart rate in beats per minute. (1)

60/0.7 = 86

Use the data in Figure 1 and your answer to the last question to calculate the man's cardiac output. Show your working. (2)

7998; Heart rate x stroke volume

Write the equation for the reaction of sodium iodide with concentrated sulfuric acid - observations? Is this a redox reaction?

8NaI(s) + 5H2SO4(aq) → 4Na2SO4(s) + 4I2(s) + H2S(g) + 4H2O(l) Black solid (I2) and toxic gas that smells of rotten eggs (H2S) This is a redox reaction

Draw the alpha helix and the β-pleated sheet Draw an example of what the alpha helix might look like when coiled into a tertiary structure.

9. Refer to big sheets 10. Refer to big sheets

Bent, 104.5

2 bond pairs, 2 lone pairs: name and bond angle(s)

Linear, 180

2 bond pairs: name and bond angle(s)

In which part of a chloroplast do the light-dependent reactions occur? (1)

Thylakoids

Rather than use chemical pesticides or biological agents, farmers often use an integrated system of chemical pesticides and biological agents to control agricultural pests. Explain the advantages of using an integrated system to control agricultural pests. (5)

(Biological Agents) Only needs one application; Pests do not develop resistance; Reduces chemical residues; (Chemical pesticides) Acts quickly; Can apply to specific area

In healthy lungs, a gradient is maintained between the concentration of oxygen in the alveoli and the concentration of oxygen in the lung capillaries. Describe how ventilation helps to maintain this difference in oxygen concentration. (2)

(In alveolus) Brings in air containing a higher oxygen concentration; Removes air with a lower oxygen concentration

Describe two differences between the breathing of a person with emphysema and a person without emphysema. (2)

(In emphysema) A lower volume breathed in and out; Faster breathing

(Refer to June 2012 paper) The graph shows the concentration of four hormones in a woman's blood during one oestrous cycle. Explain how the graph supports the following statements. (i) Oestrogen causes the release of LH. (ii) The woman did not become pregnant during this cycle. (2)

(i) LH peaks after oestrogen peaks; (ii) Progesterone returns to start

Four factors may affect the size of a human population. They are Birth rate (B) Death rate (D) Emigration rate (E) Immigration rate (I). Use all the letters B, D, E and I to write a formula showing (i) a population that stays the same size (1) (ii) a population that is increasing in size. (1)

(i) (B + I) - (D + E) = 0; (ii) (B + I) - (D + E) > 0

Give two ways in which anaerobic respiration of glucose in yeast is (i) similar to anaerobic respiration of glucose in a muscle cell; (ii) different from anaerobic respiration of glucose in a muscle cell. (4)

(i) ATP formed; glycolysis involved; (ii) ethanol formed by yeast, lactate by muscle cell; CO2 released by yeast but not by muscle cell

High concentrations of ATP inhibit an enzyme involved in glycolysis. (i) Describe how inhibition of glycolysis will affect the production of ATP by the electron transfer chain. (1) (ii) Explain this effect. (3)

(i) ATP production stops; (ii) No reduced NAD released; Krebs cycle inhibited; Movement of electrons down the chain stops

(Refer to BYB1 June 2005 paper) Two samples of the roots of pea plants were placed in solutions containing potassium ions. An inhibitor to prevent respiration was added to one solution. The concentrations of potassium ions in the two solutions were measured at regular intervals. The graph shows the results. Explain the decrease in the concentrations of potassium ions in the two solutions between 0 and 30 minutes. (i) With inhibitor (2) (ii) Without inhibitor (1)

(i) Absorbed by diffusion; No energy available (ii) Absorbed by active transport;

(Refer to exam q) Figure 2 shows the changes in concentration of the hormones responsible for controlling the menstrual cycle. Which curve, A, B, C or D shows changes in the concentration of: (i) FSH (ii) LH (2)

(i) C (ii) B

(Refer to Jan 2011 paper) The diagram shows a human heart as seen from the front. The main blood vessels are labelled D to G. The arrows show the pathways taken by the electrical activity involved in coordinating the heartbeat in the cardiac cycle. (i) Which of the blood vessels, D to G, carries oxygenated blood to the heart? (ii) Which of the blood vessels, D to G, carries deoxygenated blood to the lungs? (2)

(i) G (ii) E

Early experiments into the effects of light on shoot growth used gelatin and mica to test how the bending response was created. Why was (i) gelatin used? (ii) mica used? (2)

(i) Gelatin conducts chemicals but not electricity (ii) Mica conducts electricity but not chemicals

(Refer to June 2013 paper) The table shows features of fast and slow muscle fibres. Use information from the table to suggest and explain one advantage of: (i) the high glycogen content of fast muscle fibres (ii) the number of capillaries supplying slow muscle fibres (many).

(i) Glycogen broken down gives lots of glucose for anaerobic respiration; Anaerobic respiration is not very efficient; (ii) Many capillaries give large surface area for oxygen diffusion; Allows high rate of aerobic respiration

(i) What is at the centre of each anisotropic band? (ii) What is at the centre of each isotropic band? (2)

(i) H-zone (ii) Z-line

Use your knowledge of thermoregulation to explain: (i) the change in metabolic rate of the mammal when the environmental temperature increases from 5 degrees to 40 degrees (3) (ii) the increase in metabolic rate after 40 degrees (2)

(i) Higher metabolism at low temperatures; Respiration releases heat; Less heat lost at high temperatures (ii) Lack of thermoregulatory control at high temperatures; Increase in temperature increases respiration

Small samples of plant tissue were placed in a cold, isotonic solution and then treated to break open the cells to release the organelles. The different organelles were then separated. Describe a technique that could be used to (i) break open the cells (ii) separate the organelles. (2)

(i) Homogeniser (ii) Centrifuge

Myofibrils appear striped due to their alternating light-coloured and dark-coloured bands. (i) What makes up the light coloured bands? (ii) What makes up the dark coloured bands? (2)

(i) Isotropic bands - actin and myosin filaments do not overlap (ii) Anisotropic bands - actin and myosin filaments overlap

(Refer to June 2012 paper) Cows suffer from heat stress when the environmental temperature is too high. Heat stress occurs when their core body temperature rises above 39.4 degrees. The table shows how environmental temperature affects the food intake, water intake and milk production of cows in a fixed period of time. Suggest how each of the following responses helps to maintain core body temperature. (i) The change in water intake as environmental temperature increases (increases). (1) (ii) The change in food intake as environmental temperature decreases. (increases) (2)

(i) More sweating so water needs to be replaced (ii) Food intake linked to increased respiration; Food intake linked to more heat release in colder temperatures

Describe the part played by each of the following in myofibril contraction. (i) Tropomyosin (ii) Myosin (4)

(i) Moves out of the way when calcium ions bind; Allowing myosin to bind to actin; (ii) Head of myosin binds to actin and pulls actin past; Myosin detaches from actin and moves further along actin

(Refer to exam q) The menstrual cycle in humans is controlled by hormones. The equivalent cycle in cows is controlled by the same hormones. Figure 3 shows changes in the concentration of some of these hormones in a cow. (i) Name hormone A. Explain your answer. (ii) Name hormone B. Explain your answer. (2)

(i) Progesterone as it rises after ovulation (ii) LH, as it shows a sharp peak

When the same person views the spots in dim light, a single larger spot is seen. It is difficult to see the colour of the ink. Explain why (i) two separate spots can no longer be seen (2) (ii) the colour of the ink cannot easily be seen. (1)

(i) Rods; Have poor acuity; (ii) Rods activated, do not detect colour

(Refer to exam q) The volume of air breathed in and out of the lungs during each breath is called the tidal volume. The breathing rate and tidal volume were measured for a cyclist pedalling at different speeds. The graph shows the results. Describe the two curves. (i) Tidal volume (ii) Breathing rate (2)

(i) Tidal volume increases steeply, then increase slows down after 10 to 15 kmh-1; (ii) breathing rate increases slowly then steeply after 10 to 15 kmh-1

What are the monosaccharides of: (i) maltose (ii) sucrose (iii) lactose

(i) glucose and glucose (ii) glucose and fructose (iii) glucose and galactose

In each case name the structure that produces the hormone: (i) LH (ii) progesterone (iii) oestrogen

(i) pituitary gland (ii) corpus luteum in the ovary (iii) follicle in the ovary

Explain why each of the following is important in pumping blood through the heart. (i) There is a short delay in the passage of impulses through part B. (ii) The contraction of the ventricles starts at the base. (2)

(i) to allow ventricles to fill before contraction; (ii) to force the blood upwards into the arteries, out of the heart

Use your knowledge of the processes occurring at a neuromuscular junction to explain each of the following. (i) The cobra is a very poisonous snake. The molecular structure of cobra toxin is similar to the molecular structure of acetylcholine. The toxin permanently prevents muscle contraction. (2) (ii) The insecticide DFP combines with the active site of the enzyme acetylcholinesterase. The muscles stay contracted until the insecticide is lost from the neuromuscular junction. (2)

(i) toxin binds to the acetylcholine receptors; acetylcholine can not depolarise the membrane (ii) acetylcholinesterase is unable to breakdown acetylcholine; acetylcholine still available to depolarise the membrane

In an investigation, carrot seeds were planted at different densities. After 120 days, the dry mass of the carrot plants was measured. (i) What is the advantage of measuring the dry mass rather than the total mass of the carrot plants? (1) (ii) What type of competition is shown in this investigation?(1)

(i) true indication of growth (ii) intraspecific

What are 2 ways to reduce a nitrile to a primary amine? In each case, list reagents, and name the reaction, if necessary. -Display the reactions -Why is one method not used in industry?

-1. Use lithium aluminium hydride (LiAlH4 - a strong reducing agent) in a non-aqueous solvent (like dry ether), followed by some dilute sulfuric acid. 2. Use hydrogen gas with a metal catalyst like platinum or nickel at a high temperature and pressure. This is a catalytic hydrogenation reaction. -Refer to big sheets -Method 1 is not used in industry as LiAlH4 is too expensive for industrial use

-When will a lone pair in an amine become more available? -List ammonia, primary aliphatic amines and aromatic amines in order of increasing basic strength. -Draw diagrams to show the distribution of negative charge in these molecules

-A lone pair will become more available if its electron density is higher -Aromatic amines, ammonia, primary aliphatic amines -Refer to big sheets

Describe the structure of an amino acid. (4)

-Amino group (NH2) which is a basic group; -Carboxyl group (COOH) which is an acidic group; -Hydrogen atom (H); -R group which is a variety of different chemical groups

What is biodiesel? What can you use to make biodiesel? Display the conversion of a general triester (vegetable oil) to biodiesel, naming all chemicals and listing conditions.

-Biodiesel is a mixture of methyl esters of fatty acids, which can be burnt as fuel. -Biodiesel can be made from vegetable oils. Refer to big sheets

What sort of hydrocarbon chains do animal fats have - what properties do these cause?

-Mainly saturated hydrocarbon chains. -The chains are straight, so they fit together nicely with more points of contacts between them, increasing van der Waals forces of attraction between them and making them need more energy to overcome. -Therefore, animal fats have high melting points and are solids at room temperature.

What sort of hydrocarbon chains do vegetable oils have - what properties do these cause?

-Mainly unsaturated hydrocarbon chains. -Double bonds make the chains bent, so they don't fit together as nicely and have fewer points of contacts between them, weakening van der Waals forces of attraction between them and making them need less energy to overcome. -Therefore, animal fats have low melting points and are liquids at room temperature.

When do quaternary ammonium salts form and why? -Give an example of a quaternary ammonium salt. -Draw a quaternary ammonium salt, displaying the long hydrocarbon chain with its skeletal formula. -What are quaternary ammonium salts with at least one long hydrocarbon chain used as? How do these work? Commercial uses of this?

-Quaternary ammonium ions are positively charged, so will hang around with any negative ions that are near, when they are near. -Refer to big sheets. -Tetramethylammonium chloride, (CH3)4N+Cl- -Cationic surfactants - the hydrocarbon tail binds to nonpolar substances like grease, while the cationic head dissolves in water, so they're used in fabric cleaners and hair products. Positively charged part (ammonium ion) binds to negatively charged surfaces like hair and fibre, getting rid of static, so they're used in fabric con

Which indicator is used for a strong acid/ strong base titration and why? Strong acid/ weak base? Weak acid/ weak base?

-Strong acid/ strong base: methyl orange/ phenolphthalein - there's a rapid pH over the range for both indicators. -Strong acid/ weak base: methyl orange - pH changes rapidly across the range for methyl orange, but not for phenolphthalein. Weak acid/ strong base: phenolphthalein - pH changes rapidly across the range for phenolphthalein, but not for methyl orange. -Weak acid/ weak base: no indicator - there's no sharp pH change.

When does the nitration of benzene occur? What does one of the chemical act as, and how? Write the equation and display the mechanism for the nitration of benzene. What happens to the H+ ion produced? What must be done for only one NO2 group to add to the benzene ring - what is this reaction called?

-When benzene is warmed with concentrated concentrated nitric and sulfuric acids, you get nitrobenzene. -Sulfuric acid acts as a catalyst - it helps to make the nitronium ion, NO2^+, which is the electrophile. -Refer to big sheets -It reacts with the HSO4^- ion to make H2SO4 -For mononitration, you must keep the temperature below 55°C

Esters of phthalic acid are called phthalates and are used as plasticisers to soften polymers such as PVC, poly(chloroethene). Because of their many uses, phthalates have been tested for possible adverse effects to humans and to the environment. The European Council for Plasticisers and Intermediates is an organisation that represents the manufacturers of plasticisers. The text below is taken from a document written by the organisation. 'Research demonstrates that phthalates, at current and foreseeable exposure levels, do not pose a risk to human health or to the environment. Experimental evidence shows that phthalates are readily biodegradable and do not persist for long in the environment.' Suggest what needs to be done so that the public could feel confident that the research quoted above is reliable.

-experiment repeated/continued over a long period -repeated by independent body/other scientists/avoiding bias -investigate breakdown products -results made public

(Refer to June 2011 paper) The table shows pressure changes in the left side of the heart during one cardiac cycle. Between which times is the valve between the atrium and the ventricle closed? Explain your answer. (2)

0.1 and 0.5; Pressure in ventricle greater than pressure in atrium

Between which times are the atrioventricular valves closed? (1)

0.2 - 0.4 s

(Refer to exam q) The table shows the blood pressure in the left atrium, the left ventricle and the aorta at different times during part of a cardiac cycle. At which time is blood flowing into the aorta? (1)

0.3 s

Calculate the ratio of R : A for mammalian primary consumers. (R = 12.25 A = 12.50) (1)

0.98 : 1

(Refer to Jan 2012 paper) The diagram shows part of an epithelial cell from an insect's gut. This cell is adapted for the three functions listed below. Use the diagram to explain how this cell is adapted for each of these functions. Use a different feature in the diagram for each of your answers. 1) the active transport of substances from the cell into the blood (2) 2) the synthesis of enzymes (2) 3) rapid diffusion of substances from the lumen of the gut into the cytoplasm. (1)

1) Mitochondria respire; and release energy; 2)Ribosomes make proteins; Enzymes are proteins; 3)Microvilli increase surface large area

Temperature Increase of a system causes:

1) More collision energy (K.E) so more molecules have E>Ea, so more successful collisions 2) Increased collision frequency increased collision energy accounts for around 95% of the increase in the rate of reaction

What two chemicals are essential for Friedel-Crafts acylation reactions? What do they act as?

1. An acyl chloride as an electrophile 2. A halogen carrier, like AlCl3.

1. Write an equation for the reaction between chlorine and cold water. what type of reaction is this? 2. Write an equation for the reaction between chlorine and water in sunlight. what type of reaction is this?

1. Cl2(g) + H2O(l) ⇌ HCl(aq) + HClO(aq) This is a disproportionation reaction 2. 2Cl2(g) + 2H2O(l) ⇌ 4HCl(aq) + O2(g)

In terms of Brønsted-Lowry acids and bases, what is the nature of an amino acid when pH is 1. Below its isoelectric point 2. At its isoelectric point 3. Above its isoelectric point and why?

1. Conditions are more acidic than isoelectric point, so the COO^- group is likely to gain a H+ ion, so the amino acid is a Brønsted-Lowry acid. 2. Both carboxyl group and amino group are likely to be ionised, forming a zwitterion. 3. Conditions are more alkaline than the isoelectric point, so the -NH3^+ group is likely to lose a H+ ion, so the amino acid is a Brønsted-Lowry base

List the steps in using magnesium to extract titanium. Write an equation for Step 2. What does magnesium act as in Step 2?

1. Main titanium ore, TiO2, is converted to titanium(IV) chloride, TiCl4, by heating it with carbon in a stream of chlorine gas. 2. TiCl4 is purified by fractional distillation and then reduced by magnesium in a furnace at almost 1000°C: TiCl4(g) + 2Mg(l) → Ti(s) + 2MgCl2(l) Magnesium is the reducing agent

What are 4 continuous monitoring methods?

1. Measuring total volume of gas given off at regular time intervals, using a gas syringe. 2. Measuring mass loss (via mass of reaction mixture) at regular time intervals with a digital mass balance. 3. Measuring colour intensity at regular time intervals with a colorimeter - certain chemicals are coloured, and as their concentration increases, their colour intensity increases. 4. Change in pH with a pH meter: some reactions produce or use up protons, so pH falls or rises respectively.

Give 3 examples of condensation polymers. What are the links in each called, and what types of monomers is each made of?

1. Polyamides: has amide links, made up of dicarboxylic acids and diamines. 2. Polyesters: has ester links, made up of dicarboxylic acids and diols. 3. Polypeptides (proteins), a type of polyamide: has peptide links (which are really amide links), made up of amino acids.

How are calcium oxide/ carbonate used to remove sulfur dioxide from flue gases? What reactions occur in Step 2? What is the name of the solid waste product and what can it be used for?

1. Powdered CaO/CaCO3 is mixed with water to make an alkaline slurry. 2. Alkaline slurry sprayed on flue gases: CaO(s) + SO2(g) → CaSO3(s) CaCO3(s) + SO2(g) → CaSO3(s) + CO2(g) CaSO3 is calcium sulfite, used to make gypsum (CaSO4.2H2O)

Using displayed formulae, display the reactions for, via condensation polymerisation, the formation of repeating units in: 1. Polyamides 2. Polyesters 3. Polypeptides

1. Refer to big sheets 2. Refer to big sheets 3. Refer to big sheets

What are three ways of measuring reaction rate?

1. Timing how long it takes for a precipitate to form by timing how long it takes for a mark to be obscured. 2. Measuring mass decrease, on a digital mass balance. 3. Measure volume of gas given off, in a gas syringe.

Draw a diagram to display nuclei spin directions in no external magnetic field and an applied external magnetic field, with the energy axis pointing upwards. What sort of EM wave is required for nuclei aligned with an external magnetic field to flip up to the higher energy level? What must happen for nuclei opposed to an external magnetic field to flip down to the lower energy level (in alignment with the magnetic field)? Why will there be an overall absorption of energy?

18. Refer to big sheets Radio waves at the right frequency. They must emit radio waves at the right frequency. To start with there are more nuclei aligned with the magnetic field than opposing it.

The table shows the birth rate, death rate and life expectancy in England and Wales in four different years. You may assume there was no migration. Year 1851 1901 1931 1961 Birth rate per 1000 population 34.3 28.5 15.8 17.6 Death rate per 1000 population 22.0 16.9 12.3 11.9 Female life expectancy at birth / years 41.9 52.4 62.9 74.0 Male life expectancy at birth / years 39.9 48.5 58.7 68.1 Give the year when the population was growing at the slowest rate. Explain your answer. (2)

1931; smallest difference between birth and death rate

What are four rules for electronic arrangement notation?

1: Each principle and subsidiary level fills up before the next one 2: When the 3p energy level is full, the 4s level fills before the 3d 3: When an atom or ion has 3d electrons, the 4s is written after the 3d 4: Atoms that have 3d electrons always lose the 4s electrons first while forming ions

Under some conditions oxygen reacts with ribulose bisphosphate to give glycerate 3-phosphate and phosphoglycolate. This reaction is summarised in the equation RuBP + oxygen --> glycerate 3-phosphate + phosphoglycolate Phosphoglycolate takes no part in the light-independent reaction. Give the number of carbon atoms in one molecule of phosphoglycolate. (1)

2

Write equations for the reactions of sodium chloride and sodium fluoride with concentrated sulfuric acid - observations? Are these redox reactions?

2NaF(s) + H2SO4(aq) → Na2SO4(s) +2HF(g) 2NaCl(s) + H2SO4(aq) → Na2SO4(s) +2HCl(g) Misty fumes (due to HF/HCl) in both cases. Not redox reactions

Write the equation for the reaction of chlorine with sodium hydroxide. What type of reaction is this? Name the less known product and state what it does - give three uses for it?

2NaOH(aq) + Cl2(g) → NaClO(aq) + NaCl(aq) + H2O(l) This is a disproportionation reaction. NaClO(aq), sodium chlorate(I) solution, kills bacteria - it is bleach, used for: 1. Water treatment 2. Bleaching paper and textiles 3. Cleaning toilets

(Refer to June 2012 paper) Tay-Sachs disease is a human inherited disorder. Sufferers of this disease often die during childhood. The allele for Tay-Sachs disease t, is recessive to allele T, present in unaffected individuals. The diagram shows the inheritance of Tay-Sachs in one family. Explain one piece of evidence from the diagram which proves that the allele for Tay-Sachs disease is recessive. (2)

3 and 4 are both unaffected and have affected offspring; So both 3 and 4 are carriers

Trigonal pyramidal, 107

3 bond pairs, 1 lone pair: name and bond angle(s)

T-shaped, 88

3 bond pairs, 2 lone pairs: name and bond angle(s)

Trigonal planar, 120

3 bond pairs: name and bond angle(s)

Explain one piece of evidence from the diagram which shows that the gene is not on the X chromosome. (2)

3 is Rhesus positive; 3 could not receive Rhesus positive allele from mother if it were on the X chromosome

It has been estimated that an area of 8100m2 of grassland is needed to keep one cow. The productivity of grass is 21 135 kJm-2 year-1. What percentage of the energy in the grass is used in the production of new tissue in one cow? Show your working. (2)

3.74 x 10^6 x 100 ------------------------- 21135 x 8100

pH of Cr3+ metal aqua ion soln

3/4

pH of Fe3+ metal aqua ion in soln

3/4

Sea otters were close to extinction at the start of the 20th century. Following a ban on hunting sea otters, the sizes of their populations began to increase. Scientists studied the frequencies of two alleles of a gene in one population of sea otters. The dominant allele, T, codes for an enzyme. The other allele, t, is recessive and does not produce a functional enzyme. In a population of sea otters, the allele frequency for the recessive allele, t, was found to be 0.2. Use the Hardy-Weinberg equation to calculate the percentage of homozygous recessive sea otters in this population. Show your working. (2)

4; 0.2 x 0.2

Trigonal bipyramidal, 120,90

5 bond pairs: name and bond angle(s)

(Refer to exam q) In an experiment, cylinders cut from a potato were placed in sucrose solutions of different concentrations. The cylinders were measured before and after immersion in sucrose solution. The graph shows the effect of the sucrose solutions on the length of the potato cylinders. The initial length of the potato cylinder in 0.1 mol dm-3 sucrose solution was 5.0 cm. Calculate the final length of this cylinder. Show your working. (Ratio of initial length to final length of potato cylinders in 0.1 mol dm-3 is 0.9) (2)

5.0 ÷ 0.9; 5.55 cm

pH of Fe2+ metal aqua ion in soln

5/6

Draw the repeating unit of terylene (PET). Draw the repeating unit of kevlar.

50. Refer to big sheets 51. Refer to big sheets

Name 53. 54. and 55.

53. Methylpropylamine 54. Dimethylamine 55. N-ethylpropylamine

Use the graph to identify the range of wavelengths of light that would be green in colour. Give a reason for your answer. (2)

530 - 630 nm; any values within this range because there is limited absorption of light

(Refer to BYB1 June 2003 paper) The table shows the results of biochemical tests on substances found in food. Identify substances A, B and C. (3)

A = Protein B = Lipid C = Reducing sugar

Coordinate bond(Dative covalent bond)

A covalent bond in which both electrons in the shared pair come from the same atom.

What is a taxis? (2)

A directional response to a stimulus; From an unfavourable environment to a favourable one

What is a biofuel? What's the advantage of biofuels

A fuel made from biological material that's recently died Advantage: they're sustainable

What is a homologous series?

A homologous series is a bunch of organic compounds that have the same general formula and similar chemical properties.

Describe how you would decide the number of quadrats to use in order to collect representative data. (2)

A large number to make sure results are reliable; However need to make sure work can be carried out in the time available

What is a racemate? Why aren't they optically active?

A racemate (or racemic mixture) is a mixture of equal quantities of each enantiomer of an optically active compounds. Each enantiomer cancels out the other's light-rotating effect, so overall, plane-polarised light is not rotated.

What is a reflex? (2)

A rapid response to a stimulus; Which is involuntary

Equilibrium constant

A ratio worked out from the concentration of the products and reactants once a reversible reaction has reached equilibrium.

What is a Friedel-Crafts acylation reaction?

A reaction in which an acyl chloride is strengthened as an electrophile by a halogen carrier than substitutes a hydrogen atom in a benzene ring.

Endothermic reaction

A reaction that absorbs energy. ΔH is positive.

Ligand substitution reaction

A reaction where one or more ligands are changed for one or more other ligands in a metal complex ion.

What was Rutherford's new nuclear model for the atom?

A tiny positively charged nucleus at the centre, surrounded by a cloud of negative electrons. Most of the atom is empty space.

ATP and reduced NADP are two products of the light-dependent reactions. Describe one function of each of these substances in the light-independent reactions. (2)

ATP Provides energy for GP → TP; Reduced NADP reduces GP to TP

Skeletal muscle is made of bundles of fibres. Describe the role of ATP and phosphocreatine in producing contraction of a muscle fibre. (3)

ATP allows myosin to detach from actin; Phosphocreatine allows regeneration of ATP under anaerobic conditions; Phosphocreatine releases Pi to join ADP

Give two ways in which anaerobic respiration of glucose in yeast is similar to anaerobic respiration of glucose in a muscle cell. (2)

ATP formed; pyruvate formed

Another suspension of chloroplasts was set up as before. Small quantities of ADP and phosphate ions were added and then the tube was exposed to light. The blue colour disappeared more quickly. Explain why. (2)

ATP is a product of the light dependent reactions; ADP levels are a limiting factor

Humans synthesise more than their body mass of ATP each day. Explain why it is necessary for them to synthesise such a large amount of ATP. (2)

ATP is an immediate source of energy; ATP only releases a small amount of energy at a time

People who have McArdle's disease produce less ATP than healthy people. As a result, they are not able to maintain strong muscle contraction during exercise. Use your knowledge of the sliding filament theory to suggest why. (3)

ATP is needed for attachment between actin and myosin; And the movement of myosin heads, which pulls actin along; Myosin heads need to move back to original position

Explain how the amount of ATP is increased by reactions occurring inside a mitochondrion. (6)

ATP is produced in Krebs cycle; which occurs in the matrix of the mitochondria; Electrons fed into electron transport chain; on cristae of mitochondria; the electrons lose energy as they move down the chain and some of this is used to combine ADP and phosphate to form ATP; ATPase involved

Describe how ATP is made in mitochondria. (6)

ATP is produced in the Krebs cycle; Krebs cycle/link reaction produces reduced coenzyme; Electrons are released from reduced coenzymes; And pass through electron transport chain; Energy released is used to combine; ADP + Pi to make ATP

If scientists could transfer the gene that codes for nitrogenase to cereal plants, these cereal plants would be able to fix nitrogen. However, the scientists would expect these genetically engineered cereal plants to grow more slowly than cereal plants that get their nitrogen from fertiliser. Explain why they would grow more slowly. (2)

ATP needed for nitrogen fixation; So less ATP available for growth

What is transferred from the light-dependent reaction to the light-independent reaction? (2)

ATP; NADPH

The following process is part of the light-independent reactions of photosynthesis. Glycerate 3-phosphate --> Triose phosphate This process requires two substances produced in the light-dependent reactions. Name these two substances. Describe the role of each in the conversion of GP to triose phosphate. (4)

ATP; Provides energy; Reduced NADP; Adds hydrogen/reduces GP;

What is meant by visual acuity? (1)

Ability to distinguish between small objects

What is the role of the large intestine? (1)

Absorbs water

Explain why there is no further decrease in the concentration of potassium ions in the solution with the inhibitor after 60 minutes. (2)

Absorption by diffusion no longer occurs; because it has reached equilibrium

Why is Titanium a useful metal?

Abundant, low density, corrosion resistant, strong, light alloys

Positive ions accelerated by electric field to the same kinetic energy

Acceleration

The black mamba's toxin kills prey by preventing their breathing. It does this by inhibiting the enzyme acetylcholinesterase at neuromuscular junctions. Explain how this prevents breathing. (3)

Acetylcholine not broken down; Na+ ions continue to enter; Intercostal muscles stay contracted

Gangliosides are lipids found in the cell surface membranes of nerve cells. Hexosaminidase is an enzyme present in blood that breaks down gangliosides. If gangliosides are not broken down, they damage nerve cells. Hexosaminidase only breaks down gangliosides. It does not break down other lipids. Explain why this enzyme only breaks down gangliosides. (3)

Active site; Has a specific structure; Only fits to gangliosides

(Refer to exam q) The resting potential of a neurone is maintained at -70mV. A metabolic poison was applied to a neurone and the change in the resting potential was measured over several hours. The results are shown in the graph. Explain the change in resting potential that takes place after the application of the metabolic poison. (4)

Active transport stops; Sodium ions no longer pumped out; Sodium ions continue to diffuse in; Becomes less negative inside

Give two ways in which active transport is different from facilitated diffusion. (2)

Active transport uses energy; Against concentration gradient

Suggest how carbon dioxide concentration could be increased in a glasshouse. (1)

Add manure

Suggest a simple method by which you could find out whether an enzyme-catalysed reaction is being inhibited by a competitive or a non-competitive inhibitor. (2)

Addition of extra substrate; Rate of reaction increased if competitive, no change if non-competitive

What is addition polymerisation? For which monomers does this occur?

Addition polymerisation is when a monomer's double bond (in alkenes for example) open up and bond with other monomers. Addition polymers are unreactive as they are saturated molecules and the main carbon chain of

Why have our body temperatures evolved to be 37 degrees even though the optimum temperature for our enzymes is 40 degrees? (2)

Additional energy would be needed to maintain the higher temperature; At higher temperatures any further rise in temperature, e.g. during illness, might denature the enzymes

The diameter of the trunk decreased during the same period, reaching its minimum when the flow rate was highest. Use your knowledge of the cohesion-tension theory to suggest an explanation for this decrease. (2)

Adhesion of water molecules to walls of xylem; results in tension as water pulled up stem; pulling in walls

Describe how the hormone adrenaline produces glucose. (5)

Adrenaline is the first messenger; It binds to specific receptors on the cell-surface membrane of target cells; Hormone-receptor complex activates an enzyme inside the membrane; The activated enzyme converts ATP to cyclic AMP which acts as a second messenger; Cyclic AMP activates other enzymes which convert glycogen to glucose

Give the advantages and disadvantages of using biological control. (6)

Advantages: Only needs one application; Pests do not develop resistance; Does not leave chemical residues in environment; Disadvantages: Does not get rid of pest completely; May become a pest itself; Slow acting

What are advantages of catalysts? Disadvantage?

Advantages: They aren't used up, so you don't need much of it. They mean more product is made in a certain time and with a lower temperature, saving money. Disadvantage: they often only work on a single reaction.

What is the function of mitochondria? (1)

Aerobic respiration

The actual percentage of heterozygotes is likely to be lower in future generations than this answer. Explain why. (1)

Affected individuals usually do not reproduce

What is assimilation? (1)

After molecules have been absorbed they are incorporated into body tissues and used in processes within the body

Identification of halide ions

AgNO3 and HNO3 - HNO3 removes any CO3 2- impurities which would precipitate and mask results - observe colour of ppt - dissolve in dil/conc. NH3

Some people have a condition called white-coat hypertension. People with this condition develop a higher than normal heart rate and blood pressure when they are in a doctor's surgery. High heart rate is correlated with high blood pressure. Doctors investigated differences in heart rate between men with white-coat hypertension and those without the condition. They measured the men's mean heart rates: - in the doctor's surgery, by recording the pulse in the wrist for 1 minute, when the men were lying down - at home, using a portable heart rate monitor when the men were walking around - at home, using a portable heart rate monitor when the men were sleeping. The groups of men selected for this investigation were matched. Other than being men, suggest one factor for which they should have been matched. (1)

Age

All the volunteers who took part in investigation C were aged between 40 and 50 years old. Explain how choosing volunteers of a similar age improved this investigation. (1)

Age affects heart disease

What is meant by the term, ecological niche? (1)

All conditions and resources required for an organism to survive, reproduce and maintain a viable population

When a wave of electrical activity reaches the AVN, there is a short delay before a new wave leaves the AVN. Explain the importance of this short delay. (2)

Allow ventricles to fill; Before ventricles contract

Explain why the values for metabolic heat generation are given per gram of body mass. (2)

Allows comparison of animals with different masses; Increased mass means increased heat generation

Change in temperature

Alters value of Kc

What functional group does the polymer nylon contain? What types of monomer make up nylon? What do the numbers in nylon-6,6 refer to?

Amide link. Diamine and dicarboxylic acid. The numbers of carbon atoms in each monomer (the first is for the diamine, the second is for the dicarboxylic acid).

What are amides? What is their functional group. Draw the general displayed formulae for an amide and an N-substituted amide Why do amides behave differently from amines?

Amides are carboxylic acid derivatives. They contain the functional group -CONH2. Refer to big sheets The carbonyl group pulls electrons from the NH2 group.

Name the monomers that make up the active site of the enzyme. (1)

Amino acids

What are the monomers of proteins? (1)

Amino acids

Suggest why the reaction of ammonia with 1-chloro-4-nitrobenzene might be considered unexpected.

Ammonia is a nucleophile and benzene repels nucleophiles

What is an amine, essentially? What are primary, secondary and tertiary amines? What do you get if the lone pair on the nitrogen atom in the tertiary group bonds with a fourth organic group?

An ammonia molecule with one of more hydrogen atoms replaced by an organic group. Primary amine: 1 hydrogen atom is replaced by an organic group Secondary: 2 hydrogen atoms Tertiary: 3 If the lone pair on the nitrogen atom in the tertiary group bonds with a fourth organic group, you get a quaternary ammonium ion.

Inert atmosphere

An atmosphere made out of a non-reactive gas like nitrogen or helium.

Electrochemical cell

An electrical circuit made from two metal electrodes dipped in salt solutions and connected by a wire.

Standard hydrogen electrode

An electrode where hydrogen gas is bubbled through a solution of aqueous H ions under standard conditions

What happens during the ionisation stage of mass spectrometry?

An electron gun fires a beam of high energy electrons which bombards the gaseous particles, knocking off electrons leaving a positive ion

Lewis acid

An electron pair acceptor.

Lewis base

An electron pair donor.

What is an electrophile? Give examples What type of mechansim do electrophiles react with alkenes via?

An electrophile is an electron-pair acceptor: -Postitively charged ions (like H+ and NO2^+) -Polar molecules (𝛿+ atom attracted to high electron density) Mechanism: electrophilic addition

Born-Haber cycle

An enthalpy cycle that allows you to calculate the lattice enthalpy change of formation for system.

State two differences between animal hormones and plant growth factors. (Sum)

Animal hormones are made in particular organs and affect other organs some distance away. Plant growth factors are made by cells located throughout the plant and have localised effects.

(Refer to Jan 2012 paper) A single gene controls the presence of hair on the skin of cattle. The gene is carried on the X chromosome. Its dominant allele causes hair to be present on the skin and its recessive allele causes hairlessness. The diagram shows the pattern of inheritance of these alleles in a group of cattle. Use evidence from the diagram to explain that hairlessness is caused by a recessive allele. (2)

Animals 2 and 5 have hair but offspring do not; So 2 and 5 parents must be carriers

Suggest why she made repeat measurements. (1)

Anomalous result can be identified

How do antibiotics work? How are useful drug molecules often found? How can scientists speed up the search process? What's an advantage of using this method?

Antibiotics are inhibitors that block the active site of an enzyme in bacteria that helps it to make their cell walls. This causes their cell walls to weaken over time, so bacteria eventually burst. By trial and error - only certain molecules can fit into a target enzyme's active site, as the active sites are very stereospecific. By using computers to model the shape of an enzyme's active site and predict how well potential drug molecules will interact with it. They can quickly find hundreds of molecules to look for ones that might be the right shape before synthesising and testing things in the lab.

(Refer to Jan 2013 paper) Some people have a form of heart failure where their heart is not pumping blood as well as it used to. Some people with heart failure are given an artificial heart to improve circulation of blood from the left ventricle. Figure 4 shows where this type of artificial heart is connected. Name the blood vessel to which the artificial heart is connected. (1)

Aorta

(Refer to Jan 2006 paper) The diagram shows part of a leaf. The arrows show one pathway taken by water through the leaf and into the atmosphere. (Shows through cell walls.) Name the pathway shown. (1)

Apoplastic pathway

Facts about Maxwell-Boltzmann Distribution

Area = total no. of particles Y axis = no. of molecuels X axis = Kinetic energy starts at (0,0) as no molecules have no energy mean isn't at the peak of the curve Emp is at the peak (most probable energy) Energy distribution never reaches the x axis and there is no maximum energy for molecules some particles slow down after collision others speed up, allowing the reaction to reach completion

Why do arenes undergo electrophilic substitution reactions? What is substituted in this reaction? Why don't arenes undergo electrophilic addition?

Arenes contains benzene rings, which are regions of high electron density (due to the delocalised electron ring) and attract electrophiles. In this reaction, a hydrogen atom (or any other functional group on the ring) is substituted by the electrophile. -Electrophilic addition would destroy the delocalised ring of electrons.

What are compounds containing benzene rings called? What is the formula of the phenyl group? Draw chlorobenzene, nitrobenzene, 1,3-dimethylbenzene, phenol and phenylamine.

Arenes, or aromatic compounds. C6H5 Refer to big sheets

Give two differences between the structure of arteries and the structure of veins. (2)

Arteries have thicker muscular walls; Arteries have more elastic tissue

What evidence is there that the bending of shoots towards light is due to chemicals (hormones) and not electric signals? (3)

As mica conducts electricity it will not prevent electrical messages passing from tip but will prevent chemicals passing; As there is no response, message must be chemical and must pass down shaded side; Gelatin, which conducts chemicals, allows shoot to bend when placed in the shaded side

Explain why hyperpolarisation reduces the likelihood of a new action potential being created. (Sum)

As the inside of the membrane is more negative than at resting potential, more sodium ions must enter in order to reach the potential difference of an action potential, i.e. it is more difficult for depolarisation to occur. Stimulation is less likely to reach the threshold level needed for a new action potential.

How does shielding affect ionisation energy?

As the number of electrons between the outer electrons and the nucleus increases, the outer electrons feel less attraction towards the nuclear charge. This lessening pull of the nucleus by inner shells of electrons is called shielding.

How does metallic bonding explain metals ability to be shaped?

As there are no bonds holding specific ions together, the metal ions can slide over one another when the structure is pulled, so metals are malleable and ductile (can be pulled into a wire)

What is the trend in ionisation energy across periods?

As you move across a period the general trend is for the ionisation energy to increase, it gets harder to remove an electron. This is because the number of protons is increasing which means a stronger nuclear attraction. There are small drops between groups 2 and 3 due to sub-shell structure, the electron is in a new sub-shell so further away from nucleus, more electron shielding There is a drop between groups 5 and 6 due to electron repulsion. the repulsion between two electrons in an orbital means that the electrons are easier to remove from shared orbitals.

(Refer to exam q) Plant tissue culture is a method used to propagate plants. The flow diagram shows one method of plant tissue culture. Name the type of reproduction involved in plant tissue culture. (1)

Asexual reproduction

What is aspirin and how is it made? Display the reaction for its formation using ethanoic anhydride. Why is ethanoic anyhdride used in industry instead of ethanoyl chloride?

Aspirin is an ester made from reacting salicylic acid with ethanoic anhydride or ethanoyl chloride. Refer to big sheets Ethanoic anhydride is used instead of ethanoyl chloride, because: -It is cheaper than ethanoyl chloride -It is safer to use because: 1. It's less corrosive than ethanoyl chloride 2. It reacts more slowly with water than ethanoyl chloride 3. It doesn't give off toxic hydrogen chloride fumes

Describe how an action potential moves across an axon. (6)

At resting potential, high concentration of sodium ions outside membrane compared to inside, so inside is more negative; Stimulus causes some sodium channels to open so sodium diffuses into axon and membrane is depolarised; Localised electrical circuits cause sodium channels further along to open; Influx of sodium ions in this region causes depolarisation; Behind this new region of depolarisation, sodium channels close and potassium channels open and membrane is repolarised; Action potential continues in this way along the neurone

Suggest why initial rates of reaction are used to determine these orders rather than rates of reaction at other times during the experiments.

At time zero/start, unlike during the rest of the reaction, concentrations are known

Atheroma formation increases a person's risk of dying. Explain how. (5)

Atheroma is fatty material; In wall of artery; It blocks coronary artery; So less oxygen is supplied to heart muscle; Causing myocardial infarction

What is an aneurysm and how may it cause myocardial infarction? (5)

Atheromas that lead to the formation of a thrombus also weaken the artery walls; These weakened points swell to form a balloon-like, blood-filled structure called an aneurysm; These frequently burst, leading to haemorrhage; Reducing oxygen supply to body tissues served by that artery; So the tissues are unable to respire

What is the trend in atomic radius across a period?

Atomic radius decreases across a period. As the number of protons increases , the positive charge of the nucleus increases. This means electrons are pulled closer to the nucleus, making the atomic radius smaller. The extra electrons are added to the outer energy level so don't really provide any extra shielding.

How does distance from the nucleus affect ionisation energy?

Attraction falls off very rapidly with distance. An electron close to the nucleus will be much more strongly attracted than one further away.

The scientists located a large number of great tit nests. They sampled these at random. For each nest they recorded • the total number of eggs laid • the number of chicks that hatched from the eggs • the number of chicks that survived to leave the nest • the total number of feather mites on the two parent birds. Explain why the scientists sampled the nests at random. (2)

Avoids bias; Data representative

How does the hormone insulin regulate blood glucose concentration? (5)

B cells of islets of Langerhans in the pancreas detect rise in blood glucose level; Secrete insulin into blood plasma; Insulin binds with receptors on cell-surface membranes of body cells; Insulin changes tertiary structure of glucose transport protein channels, causing them to open, allowing more glucose into cells; Increases number of carrier molecules in cell-surface membrane

Pulmonary tuberculosis is a disease of the lungs. Describe the transmission and course of infection of pulmonary tuberculosis. (5)

Bacteria transmitted in droplets; Bacteria destroy epithelial cells of the alveoli; Which leads to scar tissue; This damage increases diffusion distance so less diffusion; Activation allows bacteria to enter blood and spread to other organs

The pioneer plants had different characteristics from the plants that colonised the fields after 50 years. The pioneer plants had seeds that germinate better when the temperature fluctuates. Explain the advantage of this to these pioneer plants. (2)

Bare soil temperatures fluctuate; More bare soil at start of succession

What is barium sulfate used for? Why is this suitable despite barium ions' toxicity?

Barium meal contains a suspension of barium sulfate. Barium meal, upon ingestion, coats the digestive system, so that when X-rays are fired at it, it can be imaged, since barium sulfate is opaque to X-rays and reflects them. Barium ions may be poisionous, but barium sulfate is insoluble in water, so the body can't absorb it.

Why are enzymes produced in different parts of the digestive system? (1)

Because each enzyme works fastest at a different pH

Why do people crack hydrocarbons?

Because the light fractions such as petrol and naptha are in higher demand so have a higher value. In order to meet this demand, the less valuable, heavier hydrocarbons are broken into smaller hydrocarbons (including alkenes).

This species of fish breeds at a certain time of the year. During this fish-breeding season, the mark-release-recapture technique might not give a reliable estimate. Suggest one reason why. (1)

Because the population will increase between the first and second sample

In a myelinated axon, sodium and potassium ions can only be exchanged at certain points along it. Explain why ions can only be exchanged at these points. (Sum)

Because the remainder of the axon is covered by a myelin sheath that prevents ions being exchanged.

(Refer to exam q) Lung cancer, chronic bronchitis and coronary heart disease (CHD) are associated with smoking. Tables 1 and 2 give the total numbers of deaths from these diseases in the UK in 1974. Using an example from the tables, explain why it is useful to give data for men and women separately. (2)

Because there are big differences between them; For example bronchitis is much lower in women than in men in all ages

Is benzene a nucleophile or an electrophile?

Benzene is a nucleophile.

What is benzene and what is its formula and what is its structure like? Draw a benzene ring In benzene, how many unpaired electrons does each carbon atom have? Where is it situated?

Benzene is a ring of carbon atoms: C6H6. It is a planar cyclic structure. In benzene, each carbon atom has one electron, in a p-orbital that sticks out above and below the plane of the ring. The p-orbitals form a ring of delocalised electrons.

(Refer to Jan 2012 paper) Scientists investigated the link between pollution from vehicle exhausts and the number of cases of asthma. Between 1976 and 1996, the scientists recorded changes in the following - the concentration in the air of substances from vehicle exhausts - the number of cases of asthma. The graph shows their results. Between which years on the graph was there a positive correlation between the number of cases of asthma and the concentration in the air of substances from vehicle exhausts (1)

Between 1976 and 1980

Between which years on the graph was there a negative correlation between the number of cases of asthma and the concentration in the air of substances from vehicle exhausts? (1)

Between 1980 and 1996

Scientists can clone cows. To do this they need to collect eggs from a cow. Using the graph, suggest two time periods between which the scientist should attempt to collect eggs. Give an explanation for your answer. (2)

Between days 2 and 4; Just after ovulation

Transcriptional factors are important in the synthesis of particular proteins. Describe how. (2)

Bind to DNA; Stimulate transcription

Enkephalins are neurotransmitters released by the brain and spinal cord in response to harmful stimuli. Enkephalin molecules are similar in shape to acetylcholine. Enkephalin molecules act as pain killers by inhibiting synaptic transmission. Explain how this inhibition occurs. (4)

Bind to receptors; On postsynaptic membrane; Competes with acetylcholine; Reduces depolarisation

Preventing the expression of a gene can be done by preventing transcription. Outline how this occurs. (2)

Binding site on transcriptional factor that binds to DNA is blocked by an inhibitor molecule; Prevents transcriptional factor binding to DNA so prevents transcription and protein synthesis

Aspirin is an enzyme inhibitor. Explain how aspirin prevents substrate molecules being converted to product molecules. (2)

Binds to active site; So substrate will not bind to active site of enzyme

In March, each pair of adult birds forms a separate territory. The pair stays in this territory while breeding. Using mark-release-recapture to estimate the size of a blue tit population in March would not give reliable results. Explain why. (2)

Birds are in territories and not mixing with population; Territory sample not representative of entire population

Explain what is meant by birth rate. (1)

Births per thousand per year

Describe a biochemical test to find out if the solution collected from the apparatus contains the enzyme. (2)

Biuret test; Enzyme indicated by purple colour

(Refer to Jan 2010 paper) The diagram shows tissue fluid and cells surrounding a capillary. Name fluid F. (Inside capillary) (1)

Blood plasma

Why would it not be sufficient for the heart to be made of one pump? (2)

Blood pressure drops across the blood vessels towards the capillaries; This slows the flow of blood down

Substance made when [Co(H2O)6]2+ reacts with conc. HCl

Blue Soln [CoCl4]2-

Use the graphs to explain why these reptiles often seek shade when the environmental temperature rises above 25°C. (2)

Body will overheat in very hot environments; As will generate more heat than they can lose

Parasites are organisms that live on or in host organisms. The populations of many organisms may be reduced by the effects of parasites. Feather mites are small parasites found on the wing feathers of many birds. The mites feed on the oil that the birds produce. This oil keeps the feathers in good condition. Birds unable to oil their feathers properly use more energy in maintaining their body temperature. This results in less energy being available for other processes. Scientists investigated the relationship between the numbers of feather mites and the breeding success of one species of bird, the great tit. Use the information above to suggest how feather mites could affect breeding in great tits. (2)

Breeding less successful; Due to less energy for breeding

The population number of both species of lizard varied at different times of the year. Suggest two reasons why. (2)

Breeding of lizards; Availability of water

Pesticides may be either biodegradable or non-biodegradable. Explain what is meant by biodegradable. (2)

Broken down; by bacteria

Give a reagent that could be used in a test-tube reaction to distinguish between benzene and cyclohexene. Describe what you would see when the reagent is added to each compound and the test tube is shaken.

Bromine Benzene: no reaction / colour remains / no (visible) change cyclohexene: (bromine) decolourised

Colour of Fe3+ metal aqua ion in soln

Brown

What are 3/4 methods of dealing with plastic waste? Give advantages and disadvantages of each method.

Burying, burning and sorting for reusing and recycling. 6. Refer to big sheets

How should tuberculosis be prevented? (3)

By a vaccination containing a weakened strain of mycobacterium bovis; Better education about TB; Better nutrition to ensure good immune systems

What is the only way to oxidise a tertiary alcohol?

By burning it

How is risk measured? (2)

By comparing the likelihood of harm occurring in those exposed to a hazard with those who are not exposed to it; e.g. smokers compared with non-smokers.

How do you break a protein down into its individual amino acids?

By hydrolysing it, by adding 6 M hydrochloric acid and heating the mixture under reflux for 24 hours.

Some substances can cross the cell-surface membrane of a cell by simple diffusion through the phospholipid bilayer. Describe other ways by which substances cross this membrane. (5)

By osmosis: From a high water potential to a low water potential; Through water channels; By facilitated diffusion: Through channel proteins; Down concentration gradient; By active transport: Through carrier proteins; Against concentration gradient

How do you make aromatic amines? Write out the method. Display the reaction that occurs in Step 2. What are aromatic amines used as?

By reducing a nitro compound, like nitrobenzene: 1. Heat a mixture of the nitro compound, tin metal and concentrated hydrochloric acid under reflux to make a salt. E.g. nitrobenzene makes the salt C6H5NH3+Cl-. 2. Add an alkali, like sodium hydroxide solution, to make the salt into an aromatic amine. Refer to big sheets They're used as starting molecules for dyes and pharmaceuticals

Lactose is a disaccharide sugar which can be broken down by the enzyme lactase into two monosaccharides, glucose and galactose. The formula for galactose is C6H12O6. What is the formula for lactose? (2)

C12 ; H22 O11 ;

Write the reactions for the decomposition of ozone in the upper atmosphere by trichlorofluoromethane, listing any conditions. Write an overall reaction at the end. What does the Cl. free radical act as?

CClF3 → .CCl2F + Cl. UV light needed Cl. + O3 → O2 + ClO. ClO. + O3 → 2O2 + Cl. 2O3 → 3O2 Cl. is catalyst

Compound J is ClCH2C(CH3)2CH2CH2Cl. Identify a solvent in which J can be dissolved before obtaining its 1 H n.m.r. spectrum.

CDCl3 or CD2Cl2 or C6D6 or CCl4

Benzene reacts with ethanoyl chloride in a substitution reaction to form C6H5COCH3. This reaction is catalysed by aluminium chloride. Write equations to show the role of aluminium chloride as a catalyst in this reaction.

CH3COCl +AlCl3 → CH3C^(+)O + AlCl4- AlCl4- + H+ → AlCl3 + HCl

Nitric acid (HNO3) is a strong acid. Ethanoic acid (CH3COOH) is a weak acid. Write an equation to show how ethanoic acid behaves as a weak acid in its reaction with water.

CH3COOH + H2O ⇌ CH3COO- + H3O+ OR CH3COOH ⇌ CH3COO- + H+

When pure ethanoic acid reacts with pure nitric acid, ethanoic acid acts as a base. Write an equation for this reaction.

CH3COOH + HNO3 → CH3COOH2+ + NO3-

Explain how smoking and a high blood cholesterol concentration increase the risk of developing coronary heart disease. (6)

CHD is when the heart muscle receives inadequate amounts of blood or oxygen; Smoking: Carbon monoxide is associated with plaque formation; Which increases the risk of blood clotting; Cholesterol: Fatty streaks adhere to wall of arteries; Which narrows the lumen of the artery; This can damage the endothelium; Leading to formation of thrombus

Two solutions, one with a pH of 4.00 and the other with a pH of 9.00, were left open to the air. The pH of the pH 9.00 solution changed more than that of the other solution. Suggest what substance might be present in the air to cause the pH to change. Explain how and why the pH of the pH 9.00 solution changes.

CO2 pH (It) falls/decreases acidic (gas): CO2 + 2OH- → CO3^2- + H2O OR CO2 + OH- → HCO3^-

(Refer to BYB1 June 2003 paper) Complete the structural formula of the amino acid molecule. (2)

COOH (either side); NH2 (either side)

Solubility + Use of Ca(OH)2

Ca(OH)2 is quite soluble in water used to neutralise acidic salts Ca(OH)2 = limewater - test for CO2 - Ca(OH)2 + CO2 → CaCO3 + H2O - limewater turns cloudy

What are calcium hydroxide and magnesium hydroxide used for? Write the simple ionic equation for neutralisation

Calcium hydroxide: Ca(OH)2, slaked lime, neutralises acidic soils Magnesium hydroxide: Mg(OH)2 is used as an antacid, to neutralise excess stomach acid H+(aq) + OH-(aq) → H2O(l)

Why is it important to know how much energy is involved during a reaction?

Can measure fuel energy values, can calculate energy requirements for industry, can find theoretical energy amounts for bond making and bond breaking, can predict if a reaction will take place or not

As a result of this investigation, the scientists concluded that more studies on pesticides should be carried out in natural habitats rather than under laboratory conditions. Suggest two advantages of carrying out such investigations in natural habitats. (2)

Can see effect of other biotic factors; Can see effect of abiotic factors

What causes cancer? How does this tie into what cisplatin does? How does cisplatin prevent cancer? What is a disadvantage of cisplatin?

Cancer is caused by cells in the body dividing uncontrollably and forming tumours. In order for a cell to divide it has to replicate its DNA. Cisplatin binds to DNA, causing kinks in the DNA helix which stop proteins that replicate the DNA from copying it properly. This stops tumour cells reproducing. -A nitrogen atom on a guanine base in DNA forms a coordinate bond with cisplatin's platinum ion, replacing one of the chloride ion ligands. -A second nitrogen atom from a nearby guanine (on the same strand of the DNA or the opposite one) can bond to the platinum and replace the second chloride ion. - The presence of the cisplatin complex bound to the DNA strands causes the strands to kind, so the DNA strands can;t unwind and be copied properly - so the cell can't replicate. Cisplatin can bind to DNA in normal cells as well as cancer cells, so can stop healthy hair and white blood cells from replicating, leading to hair loss and immunosuppression. It can also cause kidney damage.

Why can rod cells not detect colours? (1)

Cannot distinguish different wavelengths of light

Ecologists could have used the mark-release-recapture method to estimate the number of one species of fish in a lake. Describe how. (3)

Capture sample, mark and release; Take second sample and count marked organisms; Estimated population size: no. in 1st sample x no. in 2nd sample -------------------------------------------------- no. marked in sample 2

Chiral Carbon

Carbon atom with four different groups attached

In the light-independent reaction of photosynthesis, the carbon in carbon dioxide becomes carbon in triose phosphate. Describe how. (5)

Carbon dioxide combines with ribulose bisphosphate; To produce two molecules of glycerate 3-phosphate; Which is reduced to triose phosphate; Which requires reduced NADP; and energy from ATP

During photosynthesis, oil-palm trees convert carbon dioxide into organic substances. Describe how. (6)

Carbon dioxide combines with ribulose bisphosphate; To produce two molecules of glycerate 3-phosphate; Which is reduced to triose phosphate; Which requires reduced NADP; and energy from ATP; Triose phosphate converted to other organic substances

Clearing the forests and burning the vegetation affects the carbon dioxide concentration in the atmosphere. Describe how and explain why. (4)

Carbon dioxide concentration increases; Less vegetation so less photosynthesis; so less carbon dioxide removed from the atmosphere; Combustion produces carbon dioxide

Increased intensity of exercise leads to an increased heart rate. Explain how. (3)

Carbon dioxide detected by chemoreceptors; Changes to heart rate controlled by medulla; More impulses to SAN

The upper boundary of a forest on a mountain is called the tree line. Trees do not grow above the tree line. Other than temperature, suggest one abiotic factor that is likely to affect the position of the tree line on the mountain. (1)

Carbon dioxide;

Explain how smoking cigarettes increases the risk of developing heart disease. (3)

Carbon monoxide reduces oxygen in the blood; Nicotine increases blood pressure; Increases risk of atheroma formation

Name the chemical elements in a non-reducing sugar. (1)

Carbon, hydrogen, oxygen

What are the two types of muscle that are used involuntary? (2)

Cardiac muscle; Smooth muscle

What is the equation for cardiac output? (1)

Cardiac output = heart rate x stroke volume

The carrier molecule on its own may be able to prevent the infection of cells by HIV. Explain how. (2)

Carrier binds to protein on HIV; Prevents HIV binding to receptor on human cell

What role do motor neurones play? (1)

Carry nerve impulses away from the central nervous system to effectors

What role do sensory neurones play? (1)

Carry nerve impulses from receptors towards the central nervous system

What is a catalytic converter?

Catalytic converters can help remove the three main pollutants from vehicle exhausts (nitrogen oxides, unburnt hydrocarbons and carbon monoxide) using transition metals such as rhodium and platinum which convert them into less harmful chemicals.

What is catalytic cracking?

Catalytic cracking makes mostly motor fuels and aromatic hydrocarbons. It uses a zeolite catalyst at a slight pressure and a high temperature of 450'C. Using a catalyst cuts costs because a lower temperature and pressure can be used. It also speeds up the rate of reaction.

What can quaternary ammonium salts be used as? Give examples?

Cationic surfactants, like [C16H33N(CH3)3]+Br-. These are present in detergents, fabric cleaners, shampoos and conditioners.

Selectively breeding cattle with a low RFI may help to limit global warming. Use the information in Figure 3 to explain how. (2) Low RFI High RFI Mean rate of methane production 142.3 190.2 / g day -1

Cattle with low RFI produce less methane; Methane linked to greenhouse effect

The pulse felt in the artery in the wrist can be recorded and used to measure heart rate. Suggest why the pulse felt can be used to measure heart rate. (2)

Caused by blood pressure; From one contraction

Use your knowledge of enzymes to explain the shape of the curve for 55 °C after 20 minutes. (3)

Causes denaturation; So shape of active site changed; So substrate no longer binds to active site

When a young shoot is illuminated from one side, IAA stimulates growth on the shaded side. Explain why growth on the shaded side helps to maintain the leaves in a favourable environment. (2)

Causes plant to grow towards light; Light is required for photosynthesis;

Serotonin is a neurotransmitter released in some synapses in the brain. It is transported back out of the synaptic gap by a transport protein in the pre-synaptic membrane. Serotonin diffuses across the synaptic gap and binds to a receptor on the post-synaptic membrane. Describe how this causes depolarisation of the post-synaptic membrane. (2)

Causes sodium ion channels to open; Sodium ions enter cell and cause depolarisation

Describe the structure of neurones.

Cell body containing a nucleus and lots of RER; Dendrites which carry nerve impulses towards cell body; Axon, long fibre which carries nerve impulses away from cell body; Schwann cells which surround axon, protect it and provide electrical insulation; Myelin sheath, made of membranes of Schwann cells, rich in the lipid 'myelin' which transmits nerve impulses faster; Nodes of ranvier which are gaps between Schwann cells

The table shows some features of cells. Complete the table by putting a tick in the box if the feature is present in the cell. (3) (Cells: Cholera bacterium, Epithelial cell from intestine, Epithelial cell from alveolus of lung. Features: Cell-surface membrane, Flagellum, Nucleus)

Cell-surface membrane: all; Flagellum: Cholera bacterium; Nucleus: Epithelial cell from intestine, Epithelial cell from alveolus of lung

Outline how IAA controls tropisms. (5)

Cells in the tip of a shoot produce IAA, which is transported down the shoot; Light causes IAA to move to shaded side of shoot; Greater concentration of IAA on shaded side than light side; IAA causes elongation of cells, so cells on shaded side elongate more; Shaded side grows faster, causing shoot to bend towards light

What are chain isomers?

Chain isomers are a type of structural isomer. They have different arrangements of the carbon skeleton. Some are straight chains and others are branched in different ways.

Outline how homeostasis controls body temperature. (5)

Change in body temperature detected by thermoreceptors in skin/hypothalamus; Receptors send impulses along autonomic nervous system to coordinator, the hypothalamus; Thermoregulatory centre in hypothalamus consists of heat gain and heat loss centre; Passes information to effector, the skin, which produces appropriate response; Temperature returns to set point

A student carried out a similar experiment to yours. The graph shows her results. Explain the difference in her results at pH3 and pH4. (Low rate of reaction at pH3, high at pH4). (3)

Change in charge of enzyme; Change in shape of enzyme; More enzyme-substrate complexes formed per second at pH4

Rate of reaction

Change in concentration of a substance with unit time.

What is a stretch-mediated sodium channel? (1)

Changes its permeability to sodium when it is stretched

What evidence is there that muscle contraction is caused by actin and myosin filaments sliding past one another? (1)

Changes seen in the band patterns on myofibrils

Catalyst

Changes the rate of a chemical reaction without being chemically altered at the end of the reaction

Advantages of using Carbon for extraction

Cheap and effective, Readily available

In another experiment, the tips of shoots are removed and replaced on one side of the cut surface. It was found that the shoots bend towards the side where no tip was present. Suggest an explanation why. (3)

Chemical only moves down side that is in contact with the tip; More IAA on this side, causing elongation of cells on this side; So bends away from this side

What is the oxidation state of chlorine and oxygen in the ClO- ion?

Chlorine: +1 Oxygen: -2

Uses of haloalkanes

Chloro alkanes and chloro fluoro alkanes can be used as solvents, refrigerants and aerosol propellants

Energy enters most ecosystems through the light-dependent reaction of photosynthesis. Describe what happens during the light-dependent reaction. (5)

Chlorophyll absorbs light energy; Light energy raises energy level of electrons in chlorophyll; Electrons leave chlorophyll and pass down electron transfer chain; Energy used to join ADP and Pi to form ATP; Photolysis of water produces protons, electrons and oxygen;

HDL removes cholesterol from cells such as those in coronary artery walls. HDL takes this cholesterol to the liver where it is removed from the body. A low concentration of HDL increases the risk of coronary heart disease. Explain why. (3)

Cholesterol not removed; Atheroma forms; Oxygen supply to heart muscle reduced

[Ar] 4s1 3d5

Chromium electronic configuration

High blood cholesterol concentration is a risk factor associated with coronary heart disease. Give three other risk factors associated with coronary heart disease. (3)

Cigarette smoking; Obesity; High blood pressure

(Refer to BYB1 June 2005 paper) The diagram shows the structure of the amino acid serine. Draw a circle around each of the parts of the serine molecule which would be removed when two other amino acid molecules join directly to it. (1)

Circle drawn around either of the Hs on NH2 group and circle drawn around the OH

Cholera bacteria are prokaryotic cells. Give three structures found in prokaryotic cells but not in eukaryotic cells. (3)

Circular DNA; Plasmid; Flagellum

Give one other way that helps to maintain the difference in oxygen concentration. (1)

Circulation of blood

(Refer to BYB1 June 2005 paper) In an investigation into carbohydrase activity, the contents from part of the gut of a small animal were collected. The contents were added to starch solution at pH 7 and kept in a water bath at 25°C. At one-minute intervals, samples were removed and added to different test tubes containing dilute iodine solution. The colour intensity of each sample was determined. The graph shows the results. Explain the change in colour intensity. (2)

Colour results from starch-iodine reaction; Decrease due to breakdown of starch by carbohydrase

Colour of Al3+ metal aqua ion in soln

Colourless

What are the oxidation states of combined hydrogen, and when?

Combined: normally +1, but -1 in metal hydrides (like NaH) 0 in H2

What are the oxidation states of combined oxygen, and when?

Combined: normally -2, but -1 in peroxides (like H2O2) +2 in OF2 +1 in O2F2 0 in O2

You were told to decide for yourself when the blue-black colour failed to appear. What did you do to ensure your decision was consistent? (1)

Compared to one already changed colour

Competitive and non-competitive inhibitors affect the activity of enzymes. Explain how. (6)

Competitive inhibitor: Similar in shape to substrate and complementary to active site of enzyme; Competes for active site; So fewer enzyme-substrate complexes formed; Non-competitive inhibitor Differs in shape to substrate; Binds at position other than active site; Alters shape of active site so substrate cannot bind

Urea from animal waste can be used as a fertiliser. Some bacteria in the soil secrete the enzyme urease which hydrolyses urea into ammonia. Some of this ammonia is released into the atmosphere. NBPT is an inhibitor of urease and can be added to urea fertiliser to reduce the loss of ammonia to the atmosphere. A molecule of NBPT has a similar structure to a molecule of urea. Use this information to suggest how NBPT inhibits the enzyme urease. (2)

Complementary to active site; Competes with urea, preventing it from attaching to the active site

What is always formed in complete combustion of an alkane? What side products can you get in incomplete combustion?

Complete: carbon dioxide and water Incomplete: carbon monoxide and soot (carbon particulates)

In the solution without oxygen, explain why no magnesium ions are taken up between concentrations A and B. (1)

Concentration inside cells higher than surrounding solution

Why are condensation polymers generally stronger and more rigid than addition polymers? Display this using two general polyamide repeating units.

Condensation polymers are made up of chains containing polar bonds (e.g. C-N and C-O), so as well as Van der Waals forces of attraction, there are also permanent dipole-dipole forces of attraction and hydrogen bonds between the polymers chains, which are even stronger and take more energy to overcome. 5. Refer to big sheets

In which reaction do monosaccharides join? (1)

Condensation reaction

Intensive rearing of livestock produces large quantities of waste. Some farmers use an anaerobic digester to get rid of the waste. In an anaerobic digester, microorganisms break down the large, organic molecules in the waste. This produces methane, which is a useful fuel. It also produces organic substances that can be used as a natural fertiliser. Suggest two advantages of processing waste in anaerobic digesters rather than in open ponds. (2)

Conditions in digester can be controlled; Open ponds associated with environmental damage

What conditions are required for thermal cracking, and what are the products and their uses?

Conditions: -High temperature (up to 1000°C) -High pressure (up to 70 atm) Products: -Lots of alkenes Use: -To make plastics and other polymers

What conditions are required for catalytic cracking, and what are the products? What are advantages of using a catalyst?

Conditions: -Presence of a zeolite catalyst (hydrated aluminosilicate) -Slight pressure -High temperature (450°C) Products: -Aromatic hydrocarbons -Motor fuels Using a catalyst cuts costs, as it speeds up the reaction, saving time (time is money) and the reaction can be done at a low pressure and a lower temperature

What is the role of the pancreas in regulating blood glucose? (3)

Contains groups of hormone-producing cells (islets of Langerhans); a cells produce the hormone glucagon; B cells produce the hormone insulin

There is a one-way flow of water over the gills of a fish whereas there is a two-way flow of air in the lungs of a mammal. Suggest one advantage to a fish of this one-way flow of water over its gills. (1)

Continuous flow of O2

What are the two phases of the cardiac cycle? (2)

Contraction (systole); Relaxation (diastole)

Describe how air is taken into the lungs. (3)

Contraction of diaphragm muscles flattens diaphragm; Contraction of intercostal muscles raises ribcage; Increase in volume of thorax decreases pressure of air

Explain how a person breathes in. (4)

Contraction of intercostal muscles pulls ribs up and out; Contraction of diaphragm muscles causes it to flatten; There is an increase in volume of thorax and decrease in pressure of air; Air moves in down pressure gradient

What is the function of the autonomic nervous system? (1)

Controls the involuntary activities of internal muscles and glands

What is nitrification? (2)

Conversion of ammonium ions to nitrate and nitrite ions; by nitrifying bacteria

What is denitrification? (2)

Conversion of nitrate ions into gaseous nitrogen; by denitrifying bacteria

Wet moorland soils often contain low concentrations of nitrogen compounds, as a result of denitrification. Sundew is a plant which lives in wet moorlands. Its leaves have sticky hairs which can trap small insects that are then digested. Describe the process of denitrification. (2)

Conversion of nitrates to nitrogen gas; by denitrifying bacteria

What is nitrogen-fixation? (2)

Conversion of nitrogen gas to nitrogen-containing compounds; by nitrogen-fixing bacteria

Dead leaves contain starch. Describe how microorganisms make carbon in starch available to plants. (2)

Convert starch to monosaccharides; They release enzymes

Suggest why an increase in the diameter of the lumen of the main artery in the arm is associated with a reduced risk of coronary heart disease. (3)

Coronary artery also likely to have a wide lumen; Less chance of high blood pressure; Less chance of a blood clot developing

Explain how atheroma can lead to a heart attack. (3)

Coronary artery narrows; Restricts oxygen supply to heart muscle; Prevents respiration

The shells of this snail may be unbanded or banded. The absence or presence of bands is controlled by a single gene with two alleles. The allele for unbanded, B, is dominant to the allele for banded, b. A population of snails contained 51 % unbanded snails. Use the Hardy-Weinberg equation to calculate the percentage of this population that you would expect to be heterozygous for this gene. Show your working. (3)

Correct answer of 42%; q2 = 0.49/49% OR q = 0.7/70%; Shows understanding that 2pq = heterozygotes / carriers / shows answer is derived from 2pq

A person looks at two spots of blue ink on a piece of white paper in bright light. The two spots are close together. Under these conditions, the person can clearly see two blue, circular spots. Explain how rays of light from a spot are made to form a distinct circular image on the retina.(2)

Correct reference to refraction; By cornea and/or lens; Shape of lens changes

The scientists concluded that substances in the air from vehicle exhausts did not cause the increase in asthma between 1976 and 1980. Explain why. (3)

Correlation does not mean that there is a causal relationship; May be some other factor infuencing the increase in asthma cases; After 1980 asthma continues to rise but exhaust concentration falls

Other scientists investigated the release of methane from rice fields. They investigated the effect of adding organic material (straw) and inorganic substances on the release of methane from rice fields. Research findings are not always of direct use to farmers. What else would rice farmers need to know before acting on the results of this investigation? (2)

Cost of substance; Frequency of application

Two-spotted mites are pests of strawberry plants. Ecologists investigated the use of predatory mites to control two-spotted mites. They released predatory mites on strawberry plants infested with two-spotted mites. They then recorded the percentage of strawberry leaves occupied by two-spotted mites and by predatory mites over a 16-week period. Farmers who grow strawberry plants and read about this investigation might decide not to use these predatory mites. Suggest two reasons why. (2)

Cost of treatment; Takes a long time to act

Melting points of Group 2 Alkali Metals

Decreases down the group, due to increased atomic radius (more e- shells), weaker metallic bonding (electrostatic forces between positive ions and delocalised electrons weakens) lower charge density

Gas exchange in fish takes place in gills. Explain how two features of gills allow efficient gas exchange. (2)

Countercurrent maintains a concentration gradient; Lamellae provide a large surface area

Products when [Cr(OH)6]3- reacts with sodium hydroxide.

CrO4^2- + 3e- + 4H2O

Some seeds contain lipids. Describe how you could use the emulsion test to show that a seed contains lipids. (3)

Crush sample; With ethanol; Then add water; Lipids indicated by cloudy-white colour

Substance made when [Cu(H20)6]2+ reacts with sodium carbonate

CuCO3 Green ppt

Give two precautions the students should have taken when setting up the potometer to obtain reliable measurements of water uptake by the plant shoot. (2)

Cut shoot under water; Ensure no air bubbles are present

What is cyclohexa-1,3,5-triene? Why is benzene more stable than the theoretical compounds cyclohexa-1,3,5-triene would be? What makes it more stable?

Cyclohexa-1,3,5-triene is the name of the compounds scientists believed that benzene took the form of. 1. Cyclohexene has one double bond; when it's hydrogenated, the enthalpy change is -120kJmol^-1. 2. This suggests that that of cyclohexa-1,3,5-triene, with three double bonds, would be -360kJmol^-1. Benzene's is actually -208kJmol^-1, much less exothermic than expected. 3. Energy is put in when bonds are broken and released when bonds are made; the same bonds are made in the hydrogenation of benzene and the theoretical cyclohexa-1,3,5-triene (same energy released in bond making) so more energy must be put in to break benzene bonds than theoretical cyclohexa-1,3,5-triene bonds. 4. Therefore, benzene is more stable. the extra stability is thought to be due to the delocalised ring of electrons.

Give the location of glycolysis in a liver cell. (1)

Cytoplasm

Where, in a cell, does glycolysis occur? (1)

Cytoplasm

(Refer to June 2013 paper) Human immunodeficiency virus (HIV) particles have a specific protein on their surface. This protein binds to a receptor on the plasma membrane of a human cell and allows HIV to enter. This HIV protein is found on the surface of human cells after they have become infected with HIV. Scientists made siRNA to inhibit expression of a specific HIV gene inside a human cell. They attached this siRNA to a carrier molecule. The flow chart shows what happens when this carrier molecule reaches a human cell infected with HIV. When siRNA binds to mRNA, name the complementary base pairs holding the siRNA and mRNA together. One of the bases is named for you. (1)

Cytosine and Guanine, Adenine and Uracil

(Refer to Jan 2006 paper) The diagram shows a bacterial cell. Name the parts labelled D and E. (2)

D = plasmid E = Slime capsule

Give two similarities in the structure of a mitochondrion and a chloroplast. (2)

DNA; Ribosomes

Describe and explain how intensive rearing of domestic livestock would affect the amount of energy respired. (1)

Decrease because movement restricted

A buffer is used to maintain a constant pH. Explain why the pH of the suspension would increase during photosynthesis in the absence of a buffer. (1)

Decrease in carbon dioxide

Explain how decreasing the pH affects carbohydrase activity. (4)

Decrease in pH increases H+ ions; hydrogen bonds are broken; which changes tertiary structure; so enzyme-substrate complex no longer able to form

(Refer to Jan 2013) A student investigated an area of moorland where succession was occurring. She used quadrats to measure the percentage cover of plant species, bare ground and surface water every 10 metres along a transect. She also recorded the depth of soil at each quadrat. Her results are shown in the table. Explain how these data suggest that succession has occurred from points A to E along the transect. (3)

Decrease in percentage cover of bare ground linked to more species; Change in diversity due to more soil; Increase in depth of soil as plants die

(Refer to June 2006 paper) Emphysema is a disease that affects the alveoli of the lungs and leads to the loss of elastic tissue. The photographs show sections through alveoli of healthy lung tissue and lung tissue from a person with emphysema. Both photographs are at the same magnification. Using the evidence given above and your own knowledge, explain why a person with emphysema is unable to do vigorous exercise. (4)

Decreased surface area of alveoli; so less diffusion of gases; Therefore not enough O2; for increased respiration during exercise

First Ionisation Energy down Group 2 Alkali Metals

Decreases down the group, Outer electrons are held successively further from the nucleus outer electrons are more shielded from the positive nucleus

What are the properties of Diamond?

Diamonds carbon atoms are boned to four other carbon atoms. These are arranged in a tetrahedral shape. Diamond has a very high melting point and is very hard, it cannot conduct electricity due to all of its electrons being held in localised bonds. it can also not dissolve in a solvent.

(Refer to Jan 2012 paper) A person with asthma breathed out as hard as he could. The graph shows the volume of air he breathed out in the first 6 seconds of a breath. Curve A shows the volume before he used an inhaler. Curve B shows the volume after he used an inhaler. The diaphragm helps to bring about the changes shown by the curve A. Explain how. (3)

Diaphragm relaxes; Diaphragm moves up into a domed shape; Which decreases the volume of the thorax

The molecular structure of some pesticides makes them non-biodegradable. Explain why. (2)

Different shaped molecules; Do not fit active sites of enzymes produced by decomposers

Name the process by which totipotent cells of plant tissue culture change in appearance and develop into shoot or root cells. (1)

Differentiation

Describe and explain the symptoms of asthma. (4)

Difficulty in breathing; due to the constriction of the bronchioles and the addition of mucus within them; Tightness in chest; due to not being able to ventilate the lungs properly

IAA is a specific growth factor. Name the process by which IAA moves from the growing regions of a plant shoot to other tissues. (1)

Diffusion

Why are the digestive and respiratory systems often the sites of entry for pathogens? (3)

Diffusion takes place in these systems; so they have a large surface area and a short diffusion pathway; so it is easy for pathogens to penetrate them

Describe and explain the roles of diffusion, facilitated diffusion and active transport in the absorption of digested food by the small intestine. (6)

Diffusion: Movement down a concentration gradient; Facilitated diffusion Movement down a concentration gradient; Using channel proteins; Monosaccharides move into epithelial cells using facilitated diffusion; Active transport Movement against a concentration gradient; Energy is required; Monosaccharides move into the blood using active transport

Describe how oxygen in air in the alveoli enters the blood in capillaries. (2)

Diffusion; Across alveoli epithelium

(Refer to BYA6 June 2003 paper) Neurones of type A are found in the autonomic nervous system. The autonomic nervous system consists of the sympathetic division and the parasympathetic division. Suggest the effect that stimulation by neurones of the sympathetic division would have on the diameter of arterioles leading to skeletal muscle. Explain your answer. (2)

Dilates; More blood to muscles

Which two substances are formed when two amino acid molecules join together? (1)

Dipeptide and water

Distinguish between stabilising selection and directional selection. (4)

Directional selection: Favours alleles/phenotype at one extreme of a population; Distribution curve stays the same but the mean shifts to the left or right Stabilising selection: Favours alleles/phenotypes around the mean of the population; Distribution curve becomes narrower and higher but the mean does not change

What type of natural selection appears to have occurred in this population of sea otters? Explain how this type of selection led to a decrease in the frequency of the recessive allele. (2)

Directional; The dominant allele confers advantage

Shows how all the atoms can be arranged, and all bonds between them

Displayed formula?

Strong acids and bases

Dissociate fully in water

Weak acids and bases

Dissociate partially in water

The student wanted to calculate the rate of water uptake by the shoot in cm3 per minute. What measurements did she need to make? (2)

Distance and time; Area of capillary tube

Oxygen and water move through plasma membranes into cells. Describe two ways in which these movements are similar. (2)

Do not require energy; Movement down a concentration gradient

Unidentate

Donates one electron pair

Why do nucleophilic addition reactions involving planar bonds involving a carbon atom oft produce racemates?

Double bonds are planar (flat), so the carbon atom has an equal chance of being attacked by the nucleophile from each side, so it attacked from each side by equal amounts, so equal amounts of each enantiomer form.

Explain how the refractory period ensures that nerve impulses are kept separate from one another. (Sum)

During the refractory period the sodium channels are closed so no sodium ions can move inwards and no action potential is possible. This means there must be an interval between one impulse and the next.

Why do cones have high visual acuity? (3)

Each cone cell connected to a single neurone; So each that are stimulated will generate an impulse; So can distinguish between the separate sources of light

What does a mass spectrum chart show?

Each line represents a different isotope of an element. the height of each peak gives the relative isotopic abundance (the amount of it). For a molecular substance the peak with the greatest m/z ratio corresponds to the Mr.

(Refer to June 2010 paper) Technicians in a hospital laboratory tested urine and blood samples from a girl with diabetes at intervals over a one-year period. Each time the technicians tested her urine, they also measured her blood glucose concentration. Their results are shown in the graph. The girl who took part in this investigation was being successfully treated with insulin. The graph shows that on some occasions, the concentration of glucose in her blood was very high. Suggest why. (2)

Eaten carbohydrate; Needs more insulin

Electrophile

Electron pair acceptor

What is electron pair repulsion theory?

Electrons are all negatively charged, so the charge clouds will repel each other as much as they can. The shape of the cloud charge affects how much it repels other charges. Lone pair charge clouds repel more than bonding-pair charge clouds.

Describe the part played by the inner membrane of a mitochondrion in producing ATP. (3)

Electrons are transferred down the electron transport chain; It provides energy to actively transport protons into the space between membranes; The protons then diffuse back through the membrane through ATPase

How do you find enthalpy change from enthalpies of formation? From enthalpies of combustion?

Enthalpy change = Sum of enthalpies of formation of products - sum of enthalpies of formation of reactants = sum of enthalpies of combustion of reactants - sum of enthalpies of combustion of products

Lattice Dissociation Enthalpy

Enthalpy change to separate 1 mol of an ionic substance into its gaseous ions

Enthalpy of Hydration

Enthalpy change when 1 mol of gaseousions is converted into aqueous ions

Lattice Formation Enthalpy

Enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions.

What are enzymes? What do they do and how do they work? What is the nature of an enzyme's active site? What are substrates?

Enzymes are proteins that speed up a chemical reaction by acting as biological catalysts. Collectively, they catalyse every metabolic reaction in the bodies of living organisms. Every enzyme has an area called its active site. This is the part that the substrate fits into so it can react with the enzyme. The active site is 3-d - it's part of the tertiary structure of the enzyme protein. Molecules that enzymes act on to speed up reactions.

Hexosaminidase is found in the blood of healthy people. People with Tay Sachs disease do not have this enzyme in their blood. Scientists are trying to find a way to give the missing enzyme to people with Tay Sachs disease. Suggest why they cannot give the enzyme as a tablet that is swallowed. (2)

Enzymes are proteins; And are broken down by acid

Identify two defences by which the body prevents the entry of pathogens. (2)

Enzymes break down pathogens; A mucous layer covers exchange surfaces that is difficult to penetrate.

Suggest what causes the rate of photosynthesis to decrease above 21°C. (2)

Enzymes denatured; Light independent reaction disrupted

Explain why maintaining a constant temperature is important in mammals. (3)

Enzymes function within a narrow range of temperatures; Fluctuations from optimum temperature reduce efficiency/denature enzymes; Need reactions to occur at a constant, predictable rate

Explain the change in milk production as environmental temperature increases. (decreases) (1)

Enzymes not working at optimum temperature

Emphysema reduces the efficiency of gas exchange in the lungs. Explain why. (4)

Epithelium walls thicken; And there is less elastic tissue in lungs; So less air expelled; Which results in a reduced concentration gradient

Le Chatelier's Principle

Equilibrium will shift to oppose any change imposed on it by the external environment

What sort of reaction occurs when lysine, an amino acid, reacts with methanol in the presence of a small amount of concentrated H2SO4

Esterification

At high temperatures, a desert iguana keeps its mouth wide open and breathes in and out rapidly. This is called panting. Explain how panting helps to reduce the body temperature of an iguana. (2)

Evaporation of water from lining of mouth; Heat transferred from blood

Suggest how the control group would have been treated. (2)

Given placebo; Otherwise treated the same

Nuclear charge: more protons in the nucleus means greater positive nuclear charge and stronger attraction of electrons to it. Distance from nucleus: attraction falls off rapidly with distance. An electron closer to the nucleus is more strongly attracted to it. Shielding: more electrons between outer electrons and nucleus means less attraction of outer electrons to nucleus.

Factors affecting first IE

The diabetic man adopted a daily routine to stabilise his blood glucose concentration within narrow limits. He ate three meals a day: breakfast, a midday meal and an evening meal. He injected insulin once before breakfast and once before the evening meal. The injection he used before breakfast was a mixture of two types of insulin. The mixture contained slow-acting insulin and fast-acting insulin. Explain the advantage of injecting both types of insulin before breakfast. (2)

Fast acting insulin reduces blood glucose from breakfast; Slow acting insulin reduces blood glucose from other meals before the evening meal

There is an optimum rate at which human sewage should flow through the reed bed. If the flow of human sewage is too fast, the nitrate concentration at point A falls. Explain why. (2)

Fast flow washes bacteria away; Not all ammonia converted to nitrate

What is atheroma and how may it cause myocardial infarction? (5)

Fatty material; In artery wall; It blocks coronary artery; Reducing oxygen supply to heart muscle; So heart muscle unable to respire

The binding of the functional form of TK to its substrate leads to cell division. Chronic myeloid leukaemia is a cancer caused by a faulty form of TK. Cancer involves uncontrolled cell division. Figure 2 shows the faulty form of TK. Suggest how faulty TK leads to chronic myeloid leukaemia. (2)

Faulty TK has a functional active site without phosphate; So, faulty TK is functional all the time

Structure of Haemoglobin

Fe2+ with Porphyrin (4x N bonds), One globin protein and one bond to either O2 or H2O.

Explain how the intensive rearing of domestic livestock increases net productivity. (4)

Fed on controlled diet so higher proportion of digested food absorbed; Movement restricted so less respiratory loss; Kept inside so less heat loss; Genetically selected for high productivity

What oxidising agents are oft used to distinguish between aldehydes and ketones? What are the observations when the oxidising agents are warmed with aldehyde and ketones?

Fehling's/ Benedict's solution -Aldehyde: brick red precipitate forms -Ketone: solution stays deep blue (no visible change) Tollens' reagent: -Aldehyde: silver mirror forms -Ketone: no visible change

The UK has higher life expectancies than the Sudan, and females have higher life expectancies than males in both. Suggest reasons for the differences in the life expectancy. (2)

Females tend to outlive males possibly because more males smoke and drink excessively; Medical care better in UK

Use the pattern of data in the table to describe two differences between males and females. (2)

Females: More likely to develop high blood pressure; Have lower risk of heart attack as they get older

The number of red-eyed females and red-eyed males in the offspring was counted. The observed ratio of red-eyed females to red-eyed males was similar to, but not the same as, the expected ratio. Suggest one reason why observed ratios are often not the same as expected ratios. (1)

Fertilisation is random

(Refer to exam q) A child was treated with genetically engineered stem cells. The graph shows the number of functioning white blood cells in the child during the year following treatment. Children who do not suffer from SCID have between 5000 and 8000 white blood cells per mm3 of blood. Describe and explain these results. (3)

Few modified cells to start with; Modified stem cells replace non-functional cells; Levels off because the number of white cells reaches the normal level

Emphysema is a disease which affects the lungs. It causes a decrease in the number of alveoli. It may also cause the alveolar walls to become thickened. Explain why people with emphysema may need to use oxygen masks to help with their breathing. (3)

Fewer alveoli decreases the surface area; The thick wall increases the diffusion pathway; Mask increases the concentration gradient

Apart from affecting the number of earthworms, suggest how a decrease in the pH of the soil slows down the rate of leaf decomposition. (2)

Fewer decomposers; Acid conditions denature enzymes

Large areas of land have to be used to grow the plants to make biofuels. Ecologists have suggested that changes in land use could lead to a decrease in biodiversity. Suggest how changes in land use could lead to a decrease in biodiversity. (2)

Fewer habitats; Fewer food sources

A Sri Lankan scientist investigated the effect of human disturbance on the organisms living on a rocky seashore. He chose three areas for the study. These areas had different amounts of human disturbance. The scientist measured human disturbance by walking from one end of the beach to the other. He recorded the number of people he encountered. Figure 1 shows his results. Site R Site G Site U Mean number of 2.2 (± 2.1) 17.6 (± 9.6) 34.6 (±11.6) people encountered per hour (± standard deviation) What conclusions can you draw about the number of people visiting Site R compared with the number of people visiting the other two sites? Give evidence from Figure 1 to support your answer. (2)

Fewest people at site R as mean is lowest; Standard deviations do not overlap so not due to chance

The photograph shows a fire-breather creating a ball of fire. Fire-breathers do this by blowing a fine mist of paraffin oil onto a flame. Some of this mist can be inhaled and may eventually lead to fibrosis. People who have been fire-breathers for many years often find they cannot breathe out properly. Explain why. (2)

Fibrosis reduces elasticity of alveoli; Due to scar tissue

How is the shape of the myosin molecule adapted to its role in muscle contraction? (4)

Fibrous protein long and thin; provides surface area for which actin can move along; Globular proteins form bulbous structures; Allows it to exactly fit the binding sites of the actin filament

What are the two different types of protein molecules? What is the general function of each? (4)

Fibrous proteins; have structural functions; Globular proteins; have metabolic functions.

What is the trend in ionisation energy down group 2?

First ionisation energy decreases down Group 2. This provided evidence that electron shells really do exist.

Describe and explain what happens to the shape of the diaphragm between times A and B. (2)

Flattens; As diaphragm contracts

(Refer to June 2012 paper) The diagram shows the position of the diaphragm at times P and Q. (P = person resting, Q = person inhaling) Describe what happens to the diaphragm between times P and Q to bring about the change in its shape. (2)

Flattens; Diaphragm muscle contracts

Suggest an explanation for why tiredness is a symptom of diabetes. (2)

Fluctuations in blood glucose level; If level below normal, insufficient glucose for the release of energy by cells during respiration

Worker termites feed the entire colony. They transfer food to other termites by two methods, mouth feeding and anal feeding. Trichonympha live in the end section of the termite gut (hind gut). In mouth feeding, the workers regurgitate chewed wood for other termites to feed on. In anal feeding, droplets of the contents of the hindgut are passed out of the anus for other termites to feed on. Newly hatched worker termites are fed by anal feeding. Suggest two advantages to the young termites of receiving food by anal feeding rather than by mouth feeding. (2)

Food already broken down; Food contains Trichonympha which can begin cellulose digestion in young

Scientists made an artificial gene which codes for insulin. They put the gene into a virus which was then injected into rats with type I diabetes. The virus was harmless to the rats but carried the gene into the cells of the rats. The treated rats produced insulin for up to 8 months and showed no side-effects. The scientists measured the blood glucose concentrations of the rats at regular intervals. While the rats were producing the insulin, their blood glucose concentrations were normal. The rats were not fed for at least 6 hours before their blood glucose concentration was measured. Explain why. (1)

Food would affect blood glucose level

Why isn't burning bioethanol really carbon neutral?

Fossil fuels must be burnt (and this releases CO2 into the atmosphere) to power machinery used to make fertiliser for crops from which glucose comes, the machinery that harvests the crops and the machinery that transports bioethanol.

Why are more cone cells found at the fovea? (2)

Fovea receives the highest intensity of light; Cone cells only respond to high intensity of light

How do you separate crude oil into its fractions?

Fractional distillation: 1. Crude oil vaporised at 350°C. 2. Vaporised crude oil enters fractionating column and rises up through trays. Largest hydrocarbons don't vaporise at all, as their boiling points are too high, but leave at the bottom of the column as a gooey residue. 3. As the crude oil rises up the fractionating column, it gets cooler. the alkane molecules have different chain lengths, so different boiling points, so condense at a different temperature and are drawn off at different levels of the column (those with lower boiling points condensing higher up). 4. Hydrocarbons with lowest boiling points don't condense - they're drawn off as gases at the top of the column.

The blood pressure decreases along the length of the capillary. What causes this decrease in pressure? (1)

Friction of capillary wall

what are Friedel-Crafts acylation reactions and why are they used?

Friedel-Crafts acylation reactions are reactions in which an acyl group (RCO-) is added to the benzene ring. Once added, side chains can be modified using further reactions to make useful products.

What's the only way to ascertain orders of reactions?

From experiments - you can't work them out from chemical equations

Sucrose is a disaccharide. It is formed from two monosaccharides P and Q. The diagram shows the structure of molecules of sucrose and monosaccharide P. (Monosaccharide P is glucose) Name monosaccharide Q. (1)

Fructose

What are functional group isomers?

Functional group isomers area type of structural isomer. They have the same atoms arranged into different functional groups.

The scientists then investigated how body temperature affected the behaviour of desert iguanas. They kept the iguanas in cages. Half of each cage was in the sun and half was covered to provide shade. The scientists continuously measured the body temperature of each iguana. They also recorded the body temperature when the iguana moved between sun and shade. Their results are shown in the graph. Describe how the movements of the iguanas between sun and shade are related to body temperature. (1)

Further away from the optimum, the greater the movement

State the complemenatrey sequence of bases to the following stretch of DNA: CCAGTTGACC

GGTCAACTGG

Reduction

Gain of electrons

Oxidising Agent

Gains electrons

The ends of tracheoles connect directly with the insect's muscle tissue and are filled with water. When flying, water is absorbed into the muscle tissue. Removal of water from the tracheoles increases the rate of diffusion of oxygen between the tracheoles and muscle tissue. Suggest one reason why. (1)

Gases diffuse faster in air than through water

The promoter DNA from sheep (Stage 3) causes transcription of genes coding for proteins found in sheep milk. Suggest the advantage of using this promoter DNA. (2)

Gene only expressed in mammary glands; Do not need to kill sheep to obtain Factor IX

(Refer to June 2011 paper) Plant physiologists attempted to produce papaya plants using tissue culture. They investigated the effects of different concentrations of two plant growth factors on small pieces of the stem tip from a papaya plant. Their results are shown in the table. Callus is a mass of undifferentiated plant cells. Plantlets are small plants. Explain the evidence from the table that cells from the stem tip are totipotent. (2)

Gives rise to new plants; So must be able to develop into different tissues

The following reaction occurs in the Krebs cycle. Enzyme Succinate ------> Fumarate A scientist investigated the effect of the enzyme inhibitor malonate on this reaction. The structure of malonate is very similar to the structure of succinate. The scientist added malonate and the respiratory substrate, pyruvate, to a suspension of isolated mitochondria. She also bubbled oxygen through the suspension. Explain why the scientist did not use glucose as the respiratory substrate for these isolated mitochondria. (2)

Glucose is used during glycolysis; Glucose cannot cross mitochondrial membranes

(Refer to exam q) Some people produce no insulin. As a result they have a condition called diabetes. In an investigation, a man with diabetes drank a glucose solution. The concentration of glucose in his blood was measured at regular intervals. The results are shown in the graph. Suggest two reasons why the concentration of glucose decreased after 1 hour even though this man's blood contained no insulin. (2)

Glucose is used in cell respiration; Glucose converted to glycogen in cells

Diabetic people who do not control their blood glucose concentration may become unconscious and go into a coma. A doctor may inject a diabetic person who is in a coma with glucagon. Explain how the glucagon would affect the person's blood glucose concentration. (2)

Glycogen to glucose; By activating enzymes

(Refer to June 2013 paper) The table contains statements about three stages of respiration. Complete the table with a tick if the statement in the first column is true for each stage of respiration in an animal. (3)

Glycolysis - NAD reduced Link reaction - occurs in mitochondria, CO2 produced and NAD reduced Krebs cycle - occurs in mitochondria, CO2 produced and NAD reduced

(Refer to Jan 2011 paper) Olestra is an artificial lipid. It is made by attaching fatty acids, by condensation, to a sucrose molecule. The diagram shows the structure of olestra. The letter R shows where a fatty acid molecule has attached. Name bond X. (1)

Glycosidic

(Refer to Jan 2011 paper) Scientists investigated the relationship between the amount of omega-3 fatty acids eaten per day and the risk of coronary heart disease. The graph shows their results. (Shows negative correlation.) Do the data show that eating omega-3 fatty acids prevents coronary heart disease? Explain your answer. (3)

Graph shows negative correlation; However correlation does not mean causation; and may be due to another factor

How do you find rate of reaction from a graph of product concentration (y-axis) against time (x-axis)?

Graph's gradient

What are the properties in Graphite?

Graphite has carbon atoms arranged in sheets of flat hexagons bonded with three bonds each. The fourth outer electron of each carbon is delocalised. The sheets of hexagons are bonded together by Van der Waals forces. Graphites weak bonds means that the layers can easily slide over one another, used in pencils and lubricants. It can also conduct electricity due to its delocalised electrons that are free to move along the sheets. It has a very high melting point due to the strong covalent bonds in the hexagon sheets. It is also insoluble.

Conservation of grassland habitats involves management of succession. Use the data in the graph to explain why. (2)

Grassland consists of small plants; Will be outcompeted by woody plants; So these woody plants must be removed

What is the advantage of having separate negative feedback mechanisms to control deviations away from normal? (1)

Greater degree of homeostatic control

The diagram shows the distribution of indoleacetic acid (IAA) in the lateral root at Stage B. Explain how this distribution of IAA causes the root to bend. (2)

Greater growth on top of root; IAA is highly concentrated at bottom of root which inhibits elongation of cells

The diversity of animal species is higher at E than A. Explain why. (2)

Greater variety of food; Greater variety of niches

The carbonyl compound CH3CH2CHO reacts very slowly with HCN. suggest why the reaction with HCN is very slow.

HCN is a weak acid / (acid) only slightly / partially dissociated/ionised [CN-] very low

Disproportionation of Chlorine + Water

HClO and HCl are produced, universal indicator is red then bleached white

Identify three lifestyle factors that contribute to CHD. (3)

High blood pressure; High blood cholesterol levels; Obesity

Why is a carbon-halogen covalent bond polar?

Halogen atoms are much more electronegative than hydrogen atoms, so more strongly attract the electron density in the covalent bond.

What are chlorofluorocarbons?

Halogenoalkane molecules in which all hydrogen atoms are replaced by chlorine and fluorine atoms

Via what type of reaction do amines react with halogenoalkanes and acyl chlorides and acid anhydrides? What does the amine react with in each case? Why can it?

Halogenoalkanes: nucleophilic substitution Acyl chlorides and acid anhydrides: nucleophilic addition-elimination Amine is a nucleophile - it has a lone pair to donate.

The structure of a phospholipid molecule is different from that of a triglyceride. Describe how a phospholipid is different. (2)

Has a phosphate; Instead of one of the fatty acids

(Refer to June 2011 paper) The flowchart shows how small interfering RNA (siRNA) affects the expression of a particular target gene. The siRNA-protein complex attaches to an mRNA molecule coding for a particular protein (step 2). Explain what causes the siRNA to attach only to one sort of mRNA molecule. (1)

Has complementary base sequence

Omega-3 fatty acids are unsaturated. What is an unsaturated fatty acid? (2)

Has double bonds; between carbon atoms

The ecologists found that each species of fish had adaptations to its niche. One of these adaptations was the shape of its mouth. Suggest how the shape of mouth is an adaptation to its niche. (2)

Has specific mouth shape for specific food; Competition between species is reduced

What is enthalpy change?

Heat energy transferred in a reaction at a constant pressure

Calorimeter: Errors in method

Heat loss, Incomplete fuel combustion, incomplete heat transfer, evapouration of fuel after weighing, measurements are sometimes not under standard conditions, heat capacity of calorimeter isn't included

What are sources of error in all calorimetry?

Heat lost to surrounding, heat absorbed by apparatus, incomplete reaction

Describe a further biochemical test to find out if substance D is a non-reducing sugar. (2)

Heat with hydrochloric acid, then hydrolyse using enzyme; Heat with Benedict's solution; Presence indicated by orange-brown colour

What conditions are required for the conversion of chloromethane to ethanenitrile?

Heat, and aqueous and ethanolic KCN.

Reflux

Heatly reaction mixture for long periods, organic vapours are condensed to liquids so they don't escape, condenser isn't sealed to prevent pressure build up and explosion - used for oxidation of aldehydes and secondary alcohols

Suggest one advantage to the termites from group C of the behaviour shown in the investigation. (2)

Helps them to leave the soil; and avoid competition

What are the symptoms of diabetes? (4)

High blood glucose level; Need to urinate excessively; Increased thirst and hunger; Tiredness

The concentrations of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours. Use your knowledge of photosynthesis to describe these changes and explain why they occur. (5)

High concentration of carbon dioxide is linked with darkness; Because photosynthesis cannot occur in darkness; In light plants use more carbon dioxide than they produce - rate of photosynthesis greater than rate of respiration; There is a decrease in carbon dioxide concentration with height; At ground level there is less light and so less photosynthesis (so more CO2)

Describe and explain the effect of oxygen concentration on the rate of photosynthesis. (2)

High levels of oxygen reduce photosynthetic rate, effect greater at higher temperatures; Because more RuBP combines with oxygen instead of carbon dioxide

Some female farm animals were given progesterone in their diet. When the progesterone was withdrawn from the diet, they all ovulated (produced eggs) a few days later. Suggest an explanation for this. (4)

High progesterone levels inhibit the production of FSH and LH; When progesterone is withdrawn from the diet, its level falls and so the production of FSH and LH resumes; FSH causes follicles to develop in the ovary; LH causes eggs to be released (ovulation)

Samples of plant and animal tissue were analysed to determine the proportions of the elements, carbon and nitrogen. In the plant tissue the ratio of carbon to nitrogen was 40:1. In the animal tissue the ratio was 8:1. Explain why the ratio is much higher in the plant tissue than in the animal tissue. (2)

High proportion of starch in plant tissues; Cellulose in cell walls; More protein in animal cells such as muscle

The scientists used a transmission electron microscope to study the structure of the amoeba. Explain why. (2)

High resolution; To see organelles

Describe and explain how the stability of a community is related to the number of species it contains. (3)

High stability with greater number of species; More species linked to more food chains; So if one species dies, others are still available as food

Scientists measured the mean temperature in a field each month between March and October. The table shows their results. Month Mean temperature / oC March 9.0 April 11.0 May 14.0 June 17.0 July 20.0 August 18.0 September 16.0 October 14.0 The gross productivity of the plants in the field was highest in July. Use the data in the table to explain why. (2)

High temperature allows enzymes to work faster; Photosynthesis reactions are faster

Using Ethene to produce ethanol

High temperatures and pressures are required, conc. H3PO4 catalyst is needed,

Disadvantages of using Carbon for extraction

High temperatures, metal carbides formed sometimes

Parathion is an organophosphate pesticide used to control insect pests on cotton plants. Although parathion is biodegradable, its breakdown by soil bacteria can take several weeks. An enzyme was isolated from a species of bacterium found in soil. Parathion was mixed with a solution of this enzyme. Suggest why parathion is broken down more rapidly by the isolated enzyme than by a soil bacterium containing the same enzyme. (1)

Higher enzyme concentration

Group of compounds which contain the same main functional group and can be represented by the same general formula. Each consecutive molecule in a homologous series differs by a CH2 group.

Homologous series?

If, for a certain reactant, a graph of rate of reaction against reactant concentration shows a straight horizontal line, a straight line from the origin with a positive gradient or a quadratic curve from the origin with a positive gradient, what is the order of the reaction with respect to that reactant?

Horizontal: zero Straight line from origin: first Quadratic: second

State three ways in which a response to a hormone differs from a response to a nerve impulse. (Sum)

Hormone response is slow, widespread and long lasting. Nervous response is rapid, localised and short lived.

Different substances are involved in coordinating responses in animals. Hormones are different from local chemical mediators such as histamine in the cells they affect. Describe how hormones are different in the cells they affect. (1)

Hormones have widespread effect

Describe how hormones and local chemical mediators reach the cells they affect. (2)

Hormones in blood; Local chemical mediators spread by diffusion

What are the two systems by which receptors communicate to effectors? (2)

Hormones; The nervous system

They enter the atmosphere and absorb lots of infrared radiation (heat) and emit some back towards Earth, keeping it warm.

How do greenhouse gases contribute to global warming?

In engines, high temperatures (over 2500°C are needed) and pressures cause nitrogen and oxygen molecules in the air to react and form nitrogen oxides. Problems: they react with unburnt hydrocarbons in the presence of sunlight to form ground-level ozone, O3.

How do nitrogen oxides form in an engine and what temperatures are generally needed? What problems do nitrogen oxide pose?

K = C + 273

How do you convert from C to K?

Fractional distillation: 1. Crude oil vaporised at 350°C. 2. Vaporised crude oil enters fractionating column and rises up through trays. Largest hydrocarbons don't vaporise at all, as their boiling points are too high, but leave at the bottom of the column as a gooey residue. 3. As the crude oil rises up the fractionating column, it gets cooler. the alkane molecules have different chain lengths, so different boiling points, so condense at a different temperature and are drawn off at different levels of the column (those with lower boiling points condensing higher up). 4. Hydrocarbons with lowest boiling points don't condense - they're drawn off as gases at the top of the column.

How do you separate crude oil into its fractions?

Describe and explain how water is exchanged between the blood and tissue fluid as blood flows along the capillary. (4)

Hydrostatic Pressure forces water out of capillary; because Hydrostatic Pressure is higher than Water Potential; Proteins remain in blood which increases Water Potential; Water Potential is now higher than Hydrostatic Pressure; So water returns by osmosis

What changes occur to a sarcomere when a muscle contracts? (3)

I-band becomes narrower; Z-lines move closer together (sarcomere shortens); H-zone becomes narrower

Colour of Iodine and Iodide

I2 → Grey solid, purple gas I- → Brown solution, black solid

Suggest how indoleacetic acid (IAA) could have caused the results for treatment (a)? (2)

IAA moves to lower side; This inhibits growth on lower side

What factors affect the colour of a transition metal?

Identity of metal Oxidation state of metal Identity of ligands Co-ordination number

In terms of the RDS, what is the significance of the reactants that appear in the rate equation and their orders?

If a reactant appears in the rate equation, either it, or a derivative, is involved in the RDS. Order of a reaction with respect to a certain reactant shows the number of molecules of that reactant involved in the RDS or that produced the derivative involved in the RDS.

What is le Chatelier's principle?

If a reaction at equilibrium is subjected to a change in concentration, pressure or temperature, equilibrium moves to counteract the change

Why is negative feedback important in maintaining a system at a set point? (3)

If the information is not fed back once an effector has returned the system to the set point; Receptor will continue to stimulate effector; Over-correction will lead to a deviation in the opposite direction

What happens if TLC plate composition, solvent and temperature change even slightly in thin-layer chromatography? It's hard to keep conditions identical, so what is done to deal with this?

If they do, you'll significantly different Rf values. If you suspect a mixture contains a certain chemical, put that chemical on the baseline of the TLC layer and run both the unkown mixture and the chemical simultaneously - if a spot in the mixture and the chemical reach the same height, they could be the same.

What is complete combustion?

If you burn (oxidise) alkanes with plenty of oxygen, you get carbon dioxide and water

The table shows some features relating to the human population of Mexico in 2007. (i) In 1990 the life expectancy was 70 years. Suggest one reason for the change in life expectancy since 1990. (1) Total population / millions: 107 Birth rate per 1000 population: 20 Death rate per 1000 population: 5 Life expectancy / years: 76

Improved medical care

Give two factors which could lead to a decrease in the death rate in a human population. (1)

Improved medical care; Improved nutrition

What is the evidence from the table that non-agouti and blotched are alleles of different genes? (1)

In Paris and London frequencies of these alleles add up to more than 1

How are amino acids joined? (3)

In a condensation reaction; Combining the OH from the carboxyl group of one amino acid with the H from the amino group of another amino acid; Which forms a peptide bond

heterogeneous

In a different state from reactants

How does the distribution of totipotent cells in animals differ from that in plants? (3)

In animals only a few cells are totipotent; Adult stem cells found in bone marrow, skin etc and embryonic stem cells; In plants many of the cells are totipotent

What is a covalent bond?

In covalent bonding, two atoms share electrons, so they've both got full outer shells of electrons. Both the positive nuclei are attracted electrostatically to the shared electrons.

What is a dative covalent bond?

In dative covalent, also known as co-ordinate bonding, one atom proved both of the shared electron in the bond.

How do nitrogen oxides form in an engine and what temperatures are generally needed? What problems do nitrogen oxide pose?

In engines, high temperatures (over 2500°C are needed) and pressures cause nitrogen and oxygen molecules in the air to react and form nitrogen oxides. Problems: they react with unburnt hydrocarbons in the presence of sunlight to form ground-level ozone, O3.

PLA is a biodegradable condensation polymer. The manufacturers of PLA claim that the material will break down to compost in just 12 weeks. Suggest one reason why PLA in landfill may take longer than 12 weeks to break down.

In landfill, no air or UV, to assist decay OR not enough water or moisture (to hydrolyse polyester)

(Refer to June 2011 paper) Scientists investigated the relationship between the percentage of fat in the diet and the death rate from breast cancer in 24 different countries. They plotted the data from each country on the graph below. Describe the information given by point A on the graph. (1)

In one country where the percentage of fat in the diet is 35%, the death rate from breast cancer is 20 per 100 000

Plants produce ATP in their chloroplasts during photosynthesis. They also produce ATP during respiration. Explain why it is important for plants to produce ATP during respiration in addition to during photosynthesis. (5)

In the dark there is no ATP production by photosynthesis; ATP cannot be stored so must be made continuously; Plant uses more ATP than produced in photosynthesis; ATP is needed for active transport; ATP is needed for synthesis of essential enzymes

Describe the role of insulin in the control of blood glucose concentration. (4)

Increase in blood glucose leads to more insulin secreted; binds to specific receptors on cells; leads to more glucose entering cells; glucose leaves the blood

Explain how stimulation of chemoreceptors during exercise results in a change in heart rate. (5)

Increase in carbon dioxide from respiration; Decrease in blood pH detected by chemoreceptors; More impulses to medulla; More impulses from medulla along sympathetic nerve; To SAN, increasing heart rate

(Refer to June 2010) Ecologists investigated succession in some abandoned crop fields. The data that they collected are shown in the graph. The curves show the trends that occurred over a period of 60 years. Explain the change in soil nitrate concentration shown on the graph. (increases) (2)

Increase in dead organisms; Leading to increase in nitrification

(Refer to Jan 2006 paper) The graph shows the flow rate in the xylem in the trunk of a tree. Explain the increase in the flow rate between 1000 and 1400 hours. (2)

Increase in evaporation rate due to increase in temperature ; increased kinetic energy of water molecules

Explain how raising the temperature to 35 °C affects carbohydrase activity. (3)

Increase in temperature increases kinetic energy; which increases formation of enzyme-substrate complexes; which increases rate of breakdown of starch

(Refer to June 2010 paper) The graph shows the rate of blood flow in different blood vessels. It also shows the total cross-sectional area of these blood vessels. The rate of blood flow decreases from the aorta to the capillaries. Use information from the graph to explain why. (1)

Increase in total cross sectional area so increase in friction

Scientists investigated the effect of NBPT on the release of ammonia from urea fertiliser added to the soil. A control experiment was carried out. This involved adding urea fertiliser only. Suggest an explanation for the increase in mass of ammonia released over the first four days in the control experiment. (2)

Increase in urease; More enzyme-substrate complexes formed for the hydrolysis of urea into ammonia

Describe how increased sympathetic stimulation increases cardiac output. (3)

Increased stimulation of SAN; Increase in heart rate; Increase in stroke volume

Explain how these structures help in the absorption of substances from the small intestine. (1)

Increased surface area for diffusion

Explain how the inner membrane is adapted to its function in mitochondria. (2)

Increased surface area; For respiration

(Refer to June 2011 paper) Desert iguanas are lizards that live in hot, dry conditions. Scientists measured the rate of oxygen consumption of desert iguanas at different body temperatures. Some of their results are shown in the table. Explain how an increase in the iguana's body temperature affects its oxygen consumption when it is at rest. (increases) (3)

Increased temperature increases rate of reactions; More ATP; Increased oxygen consumption due to increased respiration

Suggest an explanation for the difference in transpiration rate between conditions A and C. (Still air at 15 degrees and still air at 25 degrees) (2)

Increases kinetic energy; So water molecules move faster

How does insulin lower blood glucose level? (4)

Increases rate of absorption of glucose into cells; Increases respiratory rate of cells, which uses up glucose; Increases rate of conversion of glucose to glycogen in liver and muscles; Activates enzymes that convert glucose to glycogen and fat

Explain why it was important to check the repeatability of measurements. (2)

Increases the reliability of the measurements; If measurements are repeatable, anomalies are unlikely

Explain why it is important to check the repeatability of the results in an investigation. (2)

Increases the reliability of the measurements; If results are repeatable, anomalies are unlikely.

(Refer to Jan 2012 paper) A biologist investigated the rate of water movement during the day in different parts of a tree. The results are shown in the graph. Describe how the rate of water movement in the upper branches changed over the period shown in the graph. (2)

Increases then decreases; Peak at 13.00 - 14.00 hours

(Refer to Jan 2010 paper) The graph shows the effect of substrate concentration on the rate of an enzyme-controlled reaction. Describe what the graph shows about the effect of substrate concentration on the rate of this enzyme-controlled reaction. (2)

Increases then remains constant; Increases up to 27

(Refer to June 2011 paper) A protease is an enzyme that digests protein. The graph shows how the activity of a protease varies with temperature. Describe what the graph shows about the effect of temperature on the rate of reaction. (1)

Increases to 30C and then decreases

(Refer to BYB1 June 2003 paper) In mammals, amino acids are broken down and urea is formed. Urea from animal waste is often used as a natural fertiliser. Soil bacteria secrete an enzyme called urease that breaks down urea into ammonia and carbon dioxide. Some of this ammonia is released into the atmosphere. urea + water → carbon dioxide + ammonia Scientists have studied this reaction because it results in the loss of fertiliser. They have produced a substance called NBPT which is added to urea fertiliser. NBPT is an enzyme inhibitor which affects the action of the urease produced by soil bacteria. The graph shows the results of an experiment in which a standard amount of urease and of the enzyme inhibitor NBPT were added to different concentrations of urea solution. Describe and explain the effect on the rate of the reaction of increasing the urea concentration without NBPT present. (3)

Increases up to 23 units of urea since urea concentration is limiting the rate; Then levels off; Since active sites are all occupied

Describe and explain the effect on the rate of the reaction of increasing the urea concentration with NBPT present. (3)

Increases up to 50 units; NBPT reduces rate of reaction; NBPT is a competitive inhibitor

Explain how downward movement of the diaphragm leads to air entering the lungs. (2)

Increases volume in the thorax; Lowers pressure in the thorax

Air moves into the lungs between times P and Q. Explain how the diaphragm causes this. (3)

Increases volume of the thorax; Decrease in pressure; Air moves from high to lower pressure

Melting Point down group 7

Increases, increased atomic radius (molecule size), larger vdws between molecules, as more e-, more energy needed to break the forces

In equilibrium, what type of reaction does increasing temperature favour? Increasing pressure? Increasing concentration of a reactant?

Increasing temperature: endothermic reaction, in which heat is absorbed and temperature increase is reduced. Increasing pressure: reaction in which fewest moles are produced and pressure increase is reduced. Increasing concentration of a reactant: forward reaction, in which product forms and increase in reaction concentration is reduced.

Papaya plants reproduce sexually by means of seeds. Papaya plants grown from seeds are very variable in their yield. Explain why. (2)

Independent assortment; Random fertilisation

How may a drug inhibit the nervous system? (2)

Inhibit the release of the neurotransmitter; Block the receptors on the ion channels on postsynaptic neurone

Explain the effect of the non-competitive inhibitor. (2)

Inhibitor attaches to enzyme at a site other than the active site; And changes shape of active site

Figure 3 shows the effect of an impulse from neurone R on the membrane potential of neurone B. Describe the kind of synapse between neurone R and neurone B. (1)

Inhibitory

How is Type I diabetes controlled? (2)

Injections of insulin; Relative to glucose intake

Describe how a resting potential is established in an axon. (7)

Inside of axon negatively charged relative to outside; Because active transport of sodium ions out of the axon by sodium-potassium pumps is faster than active transport of potassium ions into the axon; Potassium ions diffuse out of axon but few sodium ions diffuse in as sodium gates are closed; Potassium ions stop diffusing out because they are attracted to negative state of axon and repelled by outside; Further increasing potential difference; More positive ions outside than inside, creating a chemical gradient; Equilibrium is reached, no net movement of ions

Describe how insulin reduces the concentration of glucose in the blood. (4)

Insulin binds to specific receptors on membranes; Insulin activates carrier proteins; Insulin increases the permeability of liver and muscle cells to glucose; Insulin action results in glucose conversion to glycogen

What metals can be extracted using Carbon

Iron (Fe2O3), Manganese (MnO2) and Copper (CuCO3)

In a species of snail, shell colour is controlled by a gene with three alleles. The shell may be brown, pink or yellow. The allele for brown, CB, is dominant to the other two alleles. The allele for pink, CP, is dominant to the allele for yellow, CY. Explain what is meant by a dominant allele. (1)

Is always expressed in the phenotype

Biofuels are fuels which can be produced from plants. Scientists have developed a standard method called net life-cycle carbon dioxide production (NLP) to find the overall effect of producing and using particular biofuels on carbon dioxide production. Petroleum is used as a comparison when evaluating NLPs of biofuels. Suggest two reasons why. (2)

Is widely used; Produces a large amount of carbon dioxide

Pulmonary fibrosis reduces the efficiency of gas exchange in the lungs. Explain why. (4)

It arises when scars form on the epithelium of the alveoli, causing them to become irreversibly thickened; So oxygen cannot diffuse into the blood as quickly because the diffusion pathway has been lengthened; Fibrosis also reduces elasticity of alveoli; So less air is expelled and lungs are not properly ventilated, reducing the concentration gradient

What shape does DNA have and why? What bases always pair together in DNA? Why? Draw diagrams to display the hydrogen bonds between thymine and adenine, and cytosine and guanine.

It consists of 2 polynucleotide strands that spiral together to form a double helix structure, held together by hydrogen bonds between the bases. Adenine always joins with thymine and guanine always joins with cytosine, as hydrogen bonds can only form between certain pairs of bases. Otherwise, partially charged atoms would be too close together, and repel, or too far apart, or bonding atoms wouldn't line up properly. 16. Refer to big sheets

The blood pressure is high at the start of the capillary. Explain how the left ventricle causes the blood to be at high pressure. (1)

It contracts

What happens to electronegativity down Group 7?

It decreases: larger atoms attract bond pairs less strongly, as bond pairs get further from the nucleus and more shielded from its attraction by extra inner electrons and less attracted to it.

What happens to oxidising power down Group 7? When will a halogen displace a halide ion?

It decreases: outer electrons get further from the nucleus and more shielded from it due to extra electrons, so less strongly attracted to it. When the halide ion is below it in the perioidic table.

Why is chlorine added to drinking water?

It forms chlorate(I) ions in the water, which: -Kill disease-causing microorganisms. -Some chlorine persists in water to prevent reinfection further down the supply. -Prevents the growth of algae, eliminating bad tastes and smells and removing discolouration caused by organic compounds.

Why is benzene aromatic?

It has a ring of continuously overlapping p orbitals, as it's planar, and it also has 4n+2 pi electrons in the ring (here, n=1).

How is the postsynaptic neurone adapted to receive the neurotransmitter? (Sum)

It has receptor molecules on its membrane.

What happens to the reducing power of halides down Group 7?

It increases, as oxidising power decreases.

Imatinib is a drug used to treat chronic myeloid leukaemia. Figure 3 shows how imatinib inhibits faulty TK. (Non-competitive inhibition) Using all of the information, describe how imatinib stops the development of chronic myeloid leukaemia. (2)

It is a non-competitive inhibitor - it binds to a site other than the active site; Which causes TK to be in non-functional form because the active site is a different shape

Some scientists reviewing this investigation were concerned about the validity of the results because of the use of concrete blocks. Suggest one reason why these scientists were concerned about using concrete blocks for the growth of algae. (1)

It is flat whereas rocks normally aren't

What is PVC made from and what is its IUPAC name? What are its properties? What is rigid PVC used for? What about plasticised PVC?

It is made from chloroethane - it is poly(chloroethene). PVC has long, closely packed chains, so it is hard but brittle at room temperature. -Rigid: to make drainpipes and window frames. -Plasticised: to make electrical cable insulation, flooring tiles and clothing.

What is the oxidation state of a simple monatomic ion?

Its charge

The heart muscle is myogenic. What does this mean? (1)

Its contraction is initiated from within the muscle itself, rather than by external nervous impulses.

An arteriole contains muscle fibres. Explain how these muscle fibres reduce blood flow to capillaries. (2)

Muscle contracts; Arteriole constricts

What is Ka? What is the equation for Ka for the reaction HA ⇌ H+ + A-, where HA is a weak aqueous acid? What is [A-] equal to? What does this simplify the Ka equation to?

Ka is acid dissociation constant Ka = ([H+][A-])/[HA] [A-] =[H+], so Ka = [H+]^2/[HA]

How do you work out equilibrium constant for the reaction aA + bB ⇌ dD + eE?

Kc = ([D]^d x [E]^e)/([A]^a x [B]^b)

(Refer to exam q) Figure 3 shows the pathway by which glycogen is broken down in liver and muscle cells. Suggest why it is important that muscle cells do not convert glucose phosphate to glucose. (2)

Keeps glucose in muscle cells; muscle cells need glucose for respiration

People with diarrhoea suffer fluid loss. They can use oral rehydration solutions (ORS) to replace the lost fluid. The mixture used to make an oral rehydration solution is stored as a powder. The powder can be made into a solution with boiled water. Why must boiled water be used to make an ORS? (1)

Kills bacteria

The biochemical pathway of aerobic respiration involves a number of different steps. Name one step in which carbon dioxide is produced. (1)

Krebs cycle/ Link reaction/ Pyruvate to CoA

Ionic Product of Water

Kw = [H+][OH−]

What is Kw? Write an equation for it. Changing which condition causes it to change?

Kw is the ionic product of water Kw = [H+][OH-] It depends on temperature

(Refer to June 2010 paper) Scientists investigated control of ovulation in a species of mammal. They measured the concentration of some hormones in the blood of females between January and June. The graph shows the results for one animal. The concentration of LH in the blood is controlled by negative feedback. Use the curves for progesterone and LH to explain how. (3)

LH rises; Increase in progesterone; Progesterone inhibits LH

Explain why a large, compact mammal will probably require less food per gram of body mass to maintain its body temperature in a cold climate than a small, less compact mammal. (3)

Large mammal has smaller surface area to volume ratio; So loses less heat per gram of body mass; Therefore needs less food for respiration

The fruit fly is a useful organism for studying genetic crosses. Female fruit flies are approximately 2.5 mm long. Males are smaller and possess a distinct black patch on their bodies. Females lay up to 400 eggs which develop into adults in 7 to 14 days. Fruit flies will survive and breed in small flasks containing a simple nutrient medium consisting mainly of sugars. Use this information to explain two reasons why the fruit fly is a useful organism for studying genetic crosses. (2)

Large number of eggs therefore are representative; Markings make males and females easy to identify

How are slow-twitch fibres adapted for their function? (4)

Large store of myoglobin to store large amounts of oxygen; Rich supply of blood vessels to deliver oxygen and glucose; Numerous mitochondria to produce ATP; So adapted for aerobic respiration to avoid a build-up of lactic acid

Adult toads spend most of their time on land but lay their eggs in water. These eggs hatch into tadpoles, which live in water and develop into adults. The tadpoles are much smaller than adult toads. Use this information to explain why the tadpoles are affected more rapidly by pesticides in water than adult toads. (2)

Large surface area to volume ratio; shorter diffusion pathway

Abdominal pumping is an adaptation not found in many small insects. These small insects obtain sufficient oxygen by diffusion. Explain how their small size enables gas exchange to be efficient without the need for abdominal pumping. (1)

Larger surface area to volume ratio to increase diffusion

How have mammals and birds living in warm climates adapted to these environments? (3)

Larger surface area to volume ratio; Larger extremities; Lighter coloured fur to reflect heat

Bovine somatotropin (BST) is a hormone used by some farmers in the USA to increase milk yield. BST has a number of effects. One of these is to increase the rate of mitosis. Explain how an increase in the rate of mitosis increases milk yield in cows. (2)

Larger udders; Cells are milk producing

Earthworms move away from light. Why does this increase their chances of survival? (2)

Leads them into the soil; So they can conserve water, find food and avoid predators.

In these patients, the right ventricle still produces sufficient blood flow to keep the patient alive. Suggest why the left ventricle requires the help of the artificial heart but the right ventricle does not. (2)

Left ventricle has to pump blood further around the whole body; So the left ventricle does the most work

The production of phosphoglycolate could lead to a reduction in the rate of photosynthesis. Explain how. (3)

Less GP; So reduced amount of TP; Less RuBP regenerated

Suggest how indoleacetic acid (IAA) could have caused the results for treatment (c)? (2)

Less IAA produced; Less inhibition of growth on lower side

Explain why the presence of these large air spaces reduces gas exchange. (2)

Less contact with capillaries; So less oxygen into the blood

Keeping cattle indoors, in barns, leads to a higher efficiency of energy transfer. Explain why. (1)

Less energy lost as heat

In the light-dependent reaction of photosynthesis, light energy generates ATP. Describe how. (5)

Light energy raises energy level of electrons in chlorophyll; Electrons leave chlorophyll and pass down electron transfer chain; The passage involves a series of redox reactions; Energy is released by electrons at each carrier; This energy is used to generate ATP from ADP and phosphate

Why are heavy fractions cracked to make smaller ones (and alkenes)?

Light fractions and alkenes are in higher demand and more valuable.

(Refer to June 2010) A student investigated the rate of transpiration from a leafy shoot. She used a potometer to measure the rate of water uptake by the shoot. The diagram shows the potometer used by the student. Give one environmental factor that the student should have kept constant during this investigation. (1)

Light intensity

Apart from temperature and pH, give one factor that should be kept constant during the investigation. (1)

Light intensity

(Refer to June 2011 paper) A student investigated the rate of transpiration from privet leaves. - She obtained two sets of ten privet leaves. - She left the ten leaves in set A untreated. She covered the upper surfaces of the ten leaves in set B with grease. - She weighed each set of leaves and then tied all the leaves in each set to a separate length of thread. This is shown in the diagram. - She then weighed each set of leaves every 20 minutes over a period of 2 hours and plotted a graph of her results. Give two environmental conditions that the student should have kept constant during this investigation. (2)

Light; Humidity in air

Substance made when [Co(H2O)6]2+ reacts with sodium carbonate

Lilac ppt CoCO3

1. Initiation reactions: Cl2 → 2Cl. UV light is required 2. Propagation reactions: Cl. + CH4 → .CH3 + HCl .CH3 + Cl2 → CH3CL + Cl. 3. Termination reactions: .Cl + .CH3 → CH3Cl .CH3 + .CH3 → C2H6 .Cl + .Cl → Cl2 If chlorine's in excess, .Cl free radicals start attacking chloromethane, making di-, tri- and even tetrachloromethane.

List and name the steps in the reaction of chlorine with methane to make chloromethane, naming any conditions. Identify unpaired electrons with. What happens next?

Lewis Acid

Lone Pair Acceptor

Lewis Base

Lone pair donor

Reducing Agent

Loses electrons

Emphysema is another disease of the lungs. People with emphysema may feel weak and tired. Explain why. (5)

Loss of elastic tissue in the lungs; Alveoli cannot recoil and it becomes more difficult to expel air; Which results in a reduced diffusion gradient; So less oxygen enters blood; Which results in less respiration

Oxidation

Loss of electrons

Scientists showed that plants grown in an increased concentration of carbon dioxide have a higher carbon : nitrogen ratio than plants grown in atmospheric carbon dioxide concentration. What does this suggest about the protein concentration in the plants grown in the increased concentration of carbon dioxide? Explain your answer. (2)

Lower as plants contain a lower proportion of nitrogen; Nitrogen is used to make protein

Cholera bacteria cause an increase in the secretion of chloride ions into the small intestine. Use your knowledge of water potential to explain how the increased secretion of chloride ions causes diarrhoea. (2)

Lower water potential in lumen; Water enters intestine by osmosis

People who are lactose intolerant are not able to produce the enzyme lactase. Explain why these people get diarrhoea when they drink milk containing lactose. (2)

Lower water potential in lumen; Water enters lumen by osmosis

Some people cannot digest lactose when they are adult. They could digest lactose when they were children. Use your knowledge of water potential to explain why these adults get diarrhoea when they drink milk. (2)

Lower water potential in lumen; Water enters lumen by osmosis

Cholera bacteria produce toxins which increase secretion of chloride ions into the lumen of the intestine. Explain why this results in severe diarrhoea (watery faeces). (3)

Lower water potential in the lumen of the intestine; And so water moves into lumen down a water potential gradient; So less water is reabsorbed

Many reactions take place in living cells at temperatures far lower than those required for the same reactions in a laboratory. Explain how enzymes enable this to happen. (3)

Lowers activation energy; Induced fit ensures that substrates are brought in correct sequence; And works by the enzyme slightly changing its shape so the active site is complementary to the substrate

(Refer to June 2010 paper) The graph shows changes in the volume of air in a person's lungs during breathing. The person was breathing in between times A and B on the graph. Explain how the graph shows that the person was breathing in between times A and B. (1)

Lung volume increases

Explain why chloroethanoic acid is a stronger acid than ethanoic acid.

M1 (Electronegative) chlorine withdraws electrons M2 Stabilises/reduces charge on COO- OR weakens O-H bond OR makes O-H more polar

A tripeptide was heated with hydrochloric acid and a mixture of amino acids was formed. This mixture was separated by column chromatography. Outline briefly why chromatography is able to separate a mixture of compounds.

M1 phase or eluent or solvent (or named solvent) is moving or mobile M2 stationary phase or solid or alumina/silica/resin M3 separation depends on balance between solubility or affinity (of compounds) in each phase OR different adsorption or retention OR (amino acids have) different Rf values OR (amino acids) travel at different speeds or take different times

Magnesium + Water

Magnesium burns in steam to produce MgO and H2 white flame Mg(s) + H2O(g) → MgO(s) + H2(g) Magnesium reacts with warm water to produce Mg(OH)2 and H2 Mg(s) + 2H2O(l) → Mg(OH)2 + H2 slower, no flame

What are the solubilities of magnesium hydroxide and barium sulfate in water?

Magnesium hydroxide: sparingly soluble Barium sulfate: insoluble

Explain how ventilation increases the rate of gas exchange in the alveoli. (2)

Maintains a greater diffusion gradient; to allow faster diffusion

Water containing dissolved oxygen flows over the gill in the opposite direction to the blood flow inside. Explain why this arrangement is important for efficient oxygen uptake. (2)

Maintains diffusion gradient; and allows diffusion to occur across the whole length of the lamellae

(Refer to exam q) The diagram shows part of a plasma membrane. Describe two functions of the structure made from the parts labelled X. (2)

Makes cell selectively permeable; Allows cell to maintain different concentrations either side

(Refer to exam q) People have been advised to reduce their cholesterol intake as a part of a healthy life style. The graph shows information about mean daily intake of cholesterol. Calculate which group, male or female, shows the greater percentage reduction in cholesterol intake between 1960 and 1995. Show your working. (2)

Male is 700 - 378 = 322, 322 / 700 = 46%; Female because 480 - 252 = 228 / 480 = 47.5%

Male fruit flies are more likely than female fruit flies to show a phenotype produced by a recessive allele carried on the X chromosome. Explain why. (2)

Males have one allele; Females could have dominant and recessive alleles

The substance malonate is an inhibitor of respiration. It has a structure very similar to the substrate of an enzyme that catalyses one of the reactions of respiration. Explain how malonate inhibits respiration. (2)

Malonate complementary to active site of the enzyme; Competes with substrate so prevents substrate forming enzyme-substrate complex

The R : A ratio is higher in mammalian primary consumers than in insect primary consumers. Suggest a reason for this higher value. (1)

Mammals have a high body temperature

Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them. (5)

Many alveoli and capillaries which provide a large surface area; So fast diffusion; Flattened epithelium of alveoli and capillaries; So short diffusion pathway; Circulation and breathing movements; Maintains a concentration gradient

Give examples of 2 types of useful chemicals that contain benzene rings. Why is it difficult to make chemicals that contain benzene rings?

Many dyes and pharmaceuticals contain benzene rings. They are so stable, so fairly unreactive, so it's difficult to make chemicals from them.

(Refer to Jan 2004 paper) Figure 2 shows two types of fat storage cell. Mammals living in cold conditions have more brown fat cells than mammals living in tropical conditions. Using evidence from Figure 2 to support your answer, suggest how the function of brown fat cells differs from that of white fat cells. (3)

Many mitochondria present in brown fat cells; Mitochondria release energy; Reduced fat storage in brown fat cells

Why are plastics recycled? What are 2 ways of recycling plastics after sorting them?

Many plastics are made from non-renewable oil-fractions, so it makes sense to recycle plastics as much as possible. 1. Some plastics (like poly(propene)) can be melted and remoulded. 2. Some plastics can be cracked into monomers, and these can be used to make more plastics or other chemicals.

Why do rods have low visual acuity? (3)

Many rod cells share a single neurone; Only generate a single impulse; So cannot distinguish between the separate sources of light

What is the relative mass and charge on a proton?

Mass 1 charge +1

What is the relative mass and charge on an electron?

Mass 1/2000 Charge -1

In an investigation, the rate at which phenol was broken down by the enzyme phenol oxidase was measured in solutions with different concentrations of phenol. The experiment was then repeated with a non-competitive inhibitor added to the phenol solutions. The graph shows the results. (Refer to exam q) Explain why an increase in concentration of phenol solution from 2.0 to 2.5mmoldm-3 has no effect on the rate of the reaction without inhibitor. (2)

Maximum rate at which enzyme can combine with substrate; The active site of enzyme saturated with substrate

Suggest one advantage of using Implanon rather than an oral contraceptive. (1)

May forget to take an oral contraceptive

Although BST increases milk yield in cattle, some dairy farmers in the USA do not use it. Suggest one explanation for this. (1)

May not be cost-effective

(Refer to exam q) Figure 1 shows the effect of increasing the environmental temperature on the metabolic rate of a small mammal. Suggest one way of measuring the metabolic rate. (1)

Measure the production of carbon dioxide

Describe how a potometer could be used to measure the rate of water uptake by a leafy shoot in cm3 per minute. (3)

Measure time taken; For bubble to move a given distance; Calculate cross sectional area of capillary tubing

(Refer to June 2012 paper) An amoeba is a single-celled, eukaryotic organism. Scientists used a transmission electron microscope to study an amoeba. The diagram shows its structure. Name two other structures in the diagram (other than golgi apparatus) which show that the amoeba is a eukaryotic cell. (2)

Mitochondrion; Nucleus

What are enzyme inhibitors and how do they work? What affects how much enzyme inhibition occurs?

Molecules that have a similar shape to the substrate. They compete with the substrate to bond to the active site, but no reaction follows. Instead they block the active site, so no substrate can fit in it. The relative concentrations of inhibitor and substrate - if there's a lot more of the inhibitor, it'll take up most of the active sites and very little substrate will be able to get to the enzyme. It also depends on how strongly the inhibitor bonds to the active site.

What are hydrocarbons?

Molecules which contain carbon and hydrogen atoms only

Enantiomer

Molecules with a chiral carbon atom that exist as two non-superimposable mirror images

The portable heart rate monitor recorded the men's heart rates continuously. This gave more reliable mean heart rates than those obtained by recording the pulse in the wrist for 1 minute. Suggest why it is more reliable. (2)

Monitor records heart rate over long period of time so more data collected; Anomalies in recording have less effect

What is the difference between the display of the repeating unit of an addition polymer and the monomer?

Monomer: main double bond "closed" Repeating unit: main double bond "open"

What is the monomer of a carbohydrate? (1)

Monosaccharide

Person B has emphysema. Give one piece of evidence from the table that shows this. (1)

More air left in lungs after breathing out

The horse's mean energy expenditure was higher in March than it was in August. Use information in the table to suggest why. (2)

More energy is lost in March because it is colder; Needs to maintain body temperature

Scientists investigated the distribution of three species of fish in a lake. They recorded the range of depths where each species was found. Suggest and explain one advantage to the fish of occupying different depths in the lake. (2)

More food and oxygen available; Due to less competition

Increasing Surface Area causes:

More frequent collisions so increased rate of reaction

Suggest a reason why there are numerous mitochondria in the sarcoplasm. (3)

Muscles require much energy from ATP for contractions; This energy from ATP is released during the Krebs cycle and ETC in respiration; Both of these processes take place in the mitochondria

NAA is a similar substance to IAA. It is used to control the growth of cultivated plants. Plant physiologists investigated the effect of temperature on the uptake of NAA by leaves. They sprayed a solution containing NAA on the upper and lower surfaces of a leaf. The graph shows their results. (Lower surface of leaf has a greater rate of uptake of NAA than upper surface) Explain the effect of temperature on the rate at which NAA is taken up by the lower surface of the leaf. (2)

More kinetic energy; More diffusion

Many farmers in California plant hedges around the fields in which crops are grown. They plant a large variety of plant species with a range of flowering times. These hedges are called insectary hedges because they are designed to attract insects. Explain why these insectary hedges attract a large variety of insect species. (3)

More niches; Variety of food sources; Different insects at different times of year;

Give an example of negative feedback in the oestrous cycle. (3)

More oestrogen leads to more inhibition of FSH production; Less FSH leads to less stimulation of oestrogen production; Which results in less oestrogen

The relationship between oestrogen and LH is an example of positive feedback. Explain how. (2)

More oestrogen produces more LH; Oestrogen increases further

Abdominal pumping increases the efficiency of gas exchange between the tracheoles and muscle tissue of the insect. Explain why. (2)

More oxygen enters; So maintains a greater diffusion gradient

Explain why an increase in pressure at constant temperature increases the rate of reaction

More particles in a given volume so increased frequency of collisions

Concentration/Pressure Increase of causes:

More particles per unit volume, particles collide more frequently So more effective collisions. e.g. doubling conc, doubles the number of particles per unit volume and the frequency of effective collisions

Give one way in which fluid F is different from tissue fluid. (1)

More proteins

Give two factors, other than smoking, which increase the risk of coronary heart disease. (2)

More stress; More saturated fats in diet

Blood flow in capillaries is slow. Give the advantage of this. (1)

More time for diffusion of substances

The scientists suggested that using biofuels would have a great effect on limiting climate change. Use the data in the table to evaluate this suggestion. (4)

Most biofuels show reduction in CO2; However soy-based biodiesel shows an increase in CO2; CO2 is a greenhouse gas; so global warming is affected

What is column chromatography used for? What stationary phase is used and what is it packed into? How is it done? Draw a diagram to represent column chromatography.

Mostly, purifying an organic product (to separate product from unreacted chemicals and by-products). Glass column packed with slurry of absorbent material like aluminium oxide, coated with water - the stationary phase. 1. Mixture to be separated is added to top of column and allowed to drain down into slurry. 2. Solvent run slowly and continually through column - solvent is mobile phase. 3. As mixture is washed through column, components separate out according to their solubilities in mobile phase and how strongly they're absorbed onto stationary phase (retention). 4. Each compound spends some time adsorbed onto stationary phase and some time dissolved in mobile phase - more soluble components in the mobile phase pass through the column faster. 18. Refer to big sheets

What is meant by facilitated diffusion? (2)

Movement down concentration gradient; Through channel protein

(Refer to June 2013 paper) Scientists investigated the effect of a drug called MDMA on movement of mice. They measured the amount of movement of three groups of mice, K, L and M. - Group K, mice not given MDMA. - Group L, mice given MDMA. - Group M, mutant mice that did not produce a serotonin receptor on their post-synaptic membranes and were given MDMA. The graph shows their results. The scientists concluded that MDMA affects movement by binding to serotonin receptors. How do these results support this conclusion? (3)

Movement in all groups about same before MDMA; MDMA increases movement in Group L; Little increase in mice without receptor

Why is energy needed for muscle contraction? (2)

Movement of myosin heads; Reabsorption of calcium ions into endoplasmic reticulum by active transport

Describe osmosis in terms of water potential. (3)

Movement of water; Through a partially-permeable membrane; From a higher water potential to a lower water potential

Termites are insects which live together in a large colony. Their main food is cellulose which they obtain by eating wood and other plant material. This cellulose is digested by single-celled organisms such as Trichonympha which live in the termite gut. Suggest one function of the flagella of Trichonympha. (1)

Movement to find wood particles

(Refer to Jan 2011 paper) Students measured the rate of transpiration of a plant growing in a pot under different environmental conditions. Their results are shown in the table. During transpiration, water diffuses from cells to the air surrounding a leaf. Suggest an explanation for the difference in transpiration rate between conditions A and B. (Still air and moving air)(2)

Moving air removes water vapour; And increases the water potential gradient

Explain the importance of muscle fibres in the wall of an arteriole. (2)

Muscle contracts; Allowing arteriole to constrict to regulate blood flow

The population of trees in the forest evolved adaptations to the mountain environment. Use your knowledge of selection to explain how. (3)

Mutations took place; Some better adapted for survival in mountains; Allele frequencies change

The axon of neurone A is myelinated. The axon of neurone B is non-myelinated. Explain why impulses travel faster along the axon of neurone A. (2)

Myelinated - impulse jumps from node to node; Non-myelinated - impulse travels whole length of axon membrane

The table contains some statements relating to biochemical processes in a plant cell. Complete the table with a tick if the statement is true or a cross if it is not true for each biochemical process. Glycolysis Krebs cycle light-dependent reaction of photosynthesis NAD is reduced NADP is reduced ATP is produced ATP is required

NAD is reduced - glycolysis, krebs cycle NADP is reduced - light-dependent reaction ATP is produced - all ATP is required - glycolysis

Why are aqueous conditions used in nucleophilic substitution reaction between NaOH and bromethane?

NaOH breaks water into OH- ions, so there is an excess of OH- ions, so they can displace halogen atoms in halogenoalkanes.

Ozone's effect on the atmosphere

Naturally occuring O3 layer in the upper atmosphere is beneficial - filters harmful UV radiation from the Sun O3 in the lower atm. is a pollutant and contriiibutes to smog formation

Describe the relationship between body mass and oxygen uptake. (1)

Negative correlation

The mammal maintained a constant core temperature as the environmental temperature increased from 5 degrees to 40 degrees. Name the type of mechanism involved in restoring physiological systems to their original level. (1)

Negative feedback

In humans, when the stomach starts to become full of food, receptors in the wall of the stomach are stimulated. This leads to negative feedback on the desire to eat. Suggest why this negative feedback is important. (3)

Negative feedback stops desire to eat; This limits amount eaten; Prevents risk of obesity

How is an action potential created across a neuromuscular junction? (6)

Nerve impulse received at neuromuscular junction; Synaptic vesicles fuse with presynaptic membrane; Release acetylcholine which diffuses to receptors on postsynaptic membrane; Alters its permeability to sodium ions; Sodium ions diffuse in and cause depolarisation; Acetylcholine broken down by acetylcholinesterase

Outline how a muscle relaxes. (3)

Nervous stimulation ceases; Calcium ions actively transported back into endoplasmic reticulum using energy from the hydrolysis of ATP; Absense of calcium ions allows tropomyosin to block binding sites on actin filaments again

Explain why the transmission of a series of nerve impulses along neurone B uses less energy than transmission along neurone A. (3)

Neurone B is myelinated; Less active transport of ions at nodes of Ranvier; Less ATP needed for active transport

Leguminous crop plants have nitrogen-fixing bacteria in nodules on their roots. On soils with a low concentration of nitrate ions, leguminous crops often grow better than other types of crop. Explain why. (2)

Nitrogen is converted to ammonia; To produce protein

Using your knowledge of the nitrogen cycle, explain how nitrogen from the atmosphere becomes incorporated into the soil, causing its level to increase. (5)

Nitrogen is fixed into compounds such as proteins and amino acids; by the nitrogen-fixing bacteria of the pioneer species; when pioneer species die decomposers break them down into ammonium ions; which are then broken down into nitrates and nitrites; by nitrifying bacteria

(Refer to Jan 2010 paper) Scientists investigated the number of cases of miner's lung reported in Britain between 1992 and 2006. Coal mining in Britain had been dramatically reduced by 1990.Some scientists concluded that the rise in reported cases of miner's lung after 1992 shows that the disease takes a long time to develop. Evaluate this conclusion. (2)

No because Correlation does not prove causation - there may be other factors influencing miner's lung; Not all individuals with miner's lung were reported

(Refer to Jan 2013 paper) The table shows the doctors' results. A journalist, who saw these results, stated that they showed there is no such thing as white-coat hypertension. Do these data support this statement? Give reasons for your answer. (2)

No because men with condition always have higher heart rates; However more studies are needed to support or reject statement; Using different recording methods

Substance produced when Al3+ metal aqua ion reacts with NH3 in excess

No change

Change in pressure

No change in value of Kc

Purple loosestrife is a plant which grows in Europe. It was introduced into the USA where it became a pest. Suggest why purple loosestrife became a pest when it was introduced into the USA, but is not a pest in Europe. (2)

No competition in US; Environment more favourable

Explain why temperature has little influence on the absorption of light by photosynthetic organisms. (2)

No direct enzyme involved; In the light-dependent reaction

Describe and explain how expression of the target gene is affected by siRNA. (2)

No longer able to make specific protein; Because mRNA has been cut into pieces

Carbon Neutrality of Ethanol

No net CO2 emissions into the atmosphere, due to photosynthesis of sugar crops which are used to produce glucose for fermentation

Give one feature of a prokaryotic cell that is not found in a eukaryotic cell. (1)

No nucleus

Advantages of using Hydrogen for extraction

No pollution, readily available, better purity than C (no carbides are formed)

Describe how the scientists calculated the death rate from breast cancer for each country. (1)

No. of deaths from breast cancer divided by total population × 100,000

Use the diagram to explain how a non-competitive inhibitor would decrease the rate of the reaction catalysed by this enzyme. (3)

Non-competitive inhibitor (C) binds to the enzyme at a site other than the active site; Binding causes a change in the shape of the active site; Substrate is no longer able to bind to the active site

What is meant by an abiotic factor? (1)

Non-living factor

(Refer to June 2006 paper) Emphysema is a disease that affects the alveoli of the lungs and leads to the loss of elastic tissue. The photographs show sections through alveoli of healthy lung tissue and lung tissue from a person with emphysema. Both photographs are at the same magnification. Using the evidence given above and your own knowledge, explain why a person with emphysema is unable to do vigorous exercise. (4)

Not enough O2; For increased respiration; Because there is decreased surface area of alveoli; So less diffusion of oxygen into the blood

Methane is produced by anaerobic microorganisms in the soil. The scientists found that rice fields that are not flooded do not produce large amounts of methane. Suggest why. (2)

Not flooded aerobic conditions; Not flooded less active anaerobic microorganisms

Explain why triglycerides are not considered to be polymers. (1)

Not made of monomers

What are nucleophiles? Give free examples. Why are nucleophilic substitution reactions likely to occur with halogenoalkanes?

Nucleophiles are electron-pair donors. E.g. OH-, CN- and NH3. Carbon atom in carbon-halogen bond has a partially positive (𝛿+) charge.

Co-Ordination Number

Number of co-ordinate bonds from ligands to metal ions

Fire-ants are a serious pest in parts of the USA. An investigation was carried out to find the best way to control the fire-ant population. The graph shows the results of this investigation. Describe the effect of using insecticide followed by biological control. (2)

Number of fire-ants falls rapidly; Population remains low

What is the equation used to calculate the number of moles of any substance?

Number of moles = mass(g)/ mass of one mole (mol)

Two shoots were kept in the same environmental conditions. Give one measurement that you would need to make to be able to compare water uptake by the shoots. Give a reason for your answer. (2)

Number of stomata; As larger number mean more water loss

Write the reactions for the formation of ozone in the upper atmosphere, listing any conditions.

O2 → 2O. UV light is required O2 + O. → O3

Describe how oestrogen affects gene expression. (5)

Oestrogen combines with a complementary site on a receptor molecule of the transcriptional factor; Oestrogen changes the shape of the receptor molecule; Inhibitor molecule is released from DNA binding site; Transcriptional factor can now bind with DNA; Stimulates transcription of the gene and protein synthesis

When a female human reaches the menopause, she has very few follicles left in her ovaries. Suggest a reason why levels of FSH in the blood rise in women reaching the menopause.

Oestrogen is produced in developing follicles; Menopausal women have few follicles left so produce less oestrogen; Oestrogen inhibits the production of FSH so there is less inhibition of FSH; Therefore more FSH is produced

Describe the two hormones which are produced by the ovaries. (4)

Oestrogen; causes rebuilding of uterus lining after menstruation, stimulates pituitary gland to release LH; Progesterone; maintains lining of uterus, inhibits production of FSH from pituitary gland

Phenylamine is not very soluble in water - it forms oily drops floating on water. When you add HCl, what do you see? Write an equation to explain this. What do you see when you add NaOH now? Explain this with words and an equation.

Oily drops dissolve 46. Refer to big sheets Oily droplets reappear - phenylamine is a much weaker base than NaOH, so the phenylammonium ions donate protons to the OH- ions. 47. Refer to big sheets

Explain why it is not possible to distinguish between very concentrated samples of reducing sugars using the Benedict's test, even though their concentrations are different. (1)

Once all the copper sulfate has been reduced to copper oxide, further amounts of reducing sugar cannot make a difference

What is a monomer? (1)

One of many small repeating units that combine to form a larger one called a polymer

What is pulmonary tuberculosis caused by? (1)

One of two species of rod-shaped bacteria: mycobacterium tuberculosis or mycobacterium bovis

Why is chlorine used to treat drinking water despite the risks?

Only a small concentration of chlorine is used, and the health benefits (preventing epidemics like cholera, which could kill thousands) outweigh the risks.

The scientists looked at previous studies on the effects of various pesticides on tadpoles. They found that most of these studies: 1) were carried out on tadpoles of the African clawed toad 2) measured the LC50 of each pesticide over 1 to 4 days in the absence of any biotic factor. The scientists concluded that these previous studies were of limited use when trying to assess the effects of malathion on the tadpoles of toads found in the USA. Suggest why the scientists reached this conclusion. (3)

Only carried out on one species of toad; Only tested short term; Did not look at effect of predation

Why do brightly coloured objects appear grey in dim light? (2)

Only rod cells stimulated by dim light; Rod cells cannot distinguish between different wavelengths of light

What type of isomerism is optical isomerism? What does it involve?

Optical isomerism is a type of stereoisomerism. When a chiral (or asymmetric) carbon atom has 4 different groups attached to it, the groups can be arranged around the carbon atom in different ways, so that two different molecules are made - these molecules are enantiomers/ optical isomers.

The photograph shows part of the cytoplasm of a cell. This photograph was taken using a transmission electron microscope. The structure of the organelles visible in the photograph could not have been seen using an optical (light) microscope. Explain why. (2)

Optical microscope has low resolution; Because wavelength of light not short enough

Trained sprinters have high levels of phosphocreatine in the muscles. Explain the advantage of this. (4)

Phosphocreatine stores phosphate; Used to generate ATP from ADP in anaerobic conditions; Sprinter's muscles often work strenuously and so oxygen supply is short; Phosphocreatine allows for production of ATP to continue when anaerobic respiration is not possible

Photolysis of water occurs in photosynthesis. Describe what happens during photolysis. (2)

Photolysis of water yields hydrogen protons, electrons and oxygen Energy excites electrons so that they leave the chlorphyll molecule

Potato plants originate from the Andes mountains in South America. They are adapted for survival in a cool climate. The potatoes we eat are food storage organs, called tubers, and are produced on underground stems. The graph shows the rates of photosynthesis and respiration for one variety of potato plant. When this variety was grown in a hot climate, with a mean daytime temperature of 23.5 °C, it failed to produce tubers. Use information in the graph to explain why no tubers were produced. (2)

Photosynthesis rate only just above respiration rate; Little gain in biomass or net loss in biomass due to night-time respiration

Energy from the sun may ultimately end up in dead plant matter. Describe how. (2)

Photosynthesis; Carbon-containing substances

Outline the process of the digestion of starch. (6)

Physical breakdown of food by teeth produces large surface area for chemical digestion; Amylase in the saliva from the salivary glands hydrolyses starch to maltose; Mineral salts maintain a neutral pH; Food passes to stomach and stomach muscle contracts to continue physically breaking down food; Food passes to small intestine and mixes with pancreatic juice containing pancreatic amylase which hydrolyses remaining starch to maltose; Epithelial lining of small intestine produces the enzyme maltase which hydrolyses maltose into a-glucose

Outline the two stages of digestion. (4)

Physical digestion; breaks down large pieces of food into smaller ones by structures such as teeth and the stomach wall which increases surface area for chemical digestion; Chemical digestion; breaks down large, insoluble molecules into smaller soluble ones and is carried out by enzymes through hydrolysis

What are pi orbitals and pi electrons?

Pi orbitals are covalent chemical bonds where two lobes of one involved atomic orbital overlap two lobes of the other involved atomic orbital. Each of these atomic orbitals is zero at a shared nodal plane, passing through the two bonded nuclei. Pi electrons are the electrons in pi orbitals.

Use the results of this investigation to describe and explain the process of succession. (4)

Pioneer species increases then decreases; The species makes the conditions less hostile; Pioneer species outcompeted by new competitor; G. coulteri increases and other species decrease

Describe the process of the oestrous cycle. (7)

Pituitary gland releases FSH into the blood which stimulates follicles to develop in the ovary; Follicles secrete oestrogen into the blood, causing uterus lining to build up, and inhibiting release of FSH; More oestrogen produced, stimulates pituitary gland to release FSH and LH; Surge in LH causes one follicle to release its egg (ovulation); LH stimulates empty follicle to develop into corpus luteum which secretes progesterone; Progesterone maintains thick lining of the uterus and inhibits release of FSH and LH from pituitary gland; If the egg is not fertilised, the corpus luteum degenerates and no longer produces progesterone so the lining breaks down

Using your knowledge of tropism, describe how plants' growth is adapted for survival. (2)

Plant shoots grow towards light (positive phototropism) so that their leaves can capture more light for photosynthesis; Plant roots grow away from light (negative phototropism) and towards gravity (positive geotropism) so that their roots will grow into the soil, where they are better able to absorb water and nutrients

Explain the advantage to a plant that colonises after 50 years of having a high rate of photosynthesis at low light intensities. (1)

Plant will survive when overshadowed by taller plants

The species that are present change during succession. Explain why. (2)

Plants change the environment; Less hostile habitat

Use of poly(ethene)

Plastic Bags, buckets, bottles, its flexible, easily moulded, low density, water and chemical proof

What is a plasticiser and how does it work?

Plasticisers are molecules which get in between polymer chains and push them apart, weakening the intermolecular forces between the chains, so they can slide around more. This makes a polymer easier to bend and more flexible.

You could use a scatter diagram to check the repeatability of measurements made by two observers. Describe how. (2)

Plot graph of one set of results against the other; Line should show positive correlation

End point

Point at which the indicator changes colour

Equivalence point

Point in a titration where sufficient base has been added to just neutralise the acid (or vice versa)

Why are polyalkenes and why are they very unreactive?

Polyalkenes are addition polymers made from alkenes and they are very unreactive as they are saturated molecules and the main carbon chain of a polyalkene is non-polar.

What are polymers and monomers?

Polymers are long chain molecules formed when lots of small molecules, called monomers, join together.

What are Positional isomers?

Positional isomers are a type of structural isomer. They have the same skeleton and the same atoms or groups attached but the group of atoms are attached to a different carbon atom.

(Refer to Jan 2011 paper) Scientists investigated the rate of water movement through the xylem of a twig from a tree over 24 hours. The graph shows their results. It also shows the light intensity for the same period of time. Describe the relationship between the rate of water movement through the xylem and the light intensity. (1)

Positive correlation

(Refer to June 2013 paper) The release of a substance called dopamine in some areas of the brain increases the desire to eat. Scientists measured increases in the release of dopamine in the brains of rats given different concentrations of sucrose solution to drink. Sucrose stimulates taste receptors on the tongue. The graph shows their results. Each point is the result for one rat. The scientists concluded that drinking a sucrose solution had a positive feedback effect on the rats' desire to eat. How do these data support this conclusion? (3)

Positive correlation between sucrose and dopamine concentrations; So dopamine makes them want to eat more sucrose; Positive feedback because eating leads to wanting to eat even more

Some people have used the graph to conclude that a high percentage of fat in the diet causes breast cancer. Evaluate this conclusion. (3)

Positive correlation supports conclusion; But correlation does not show causation - may be some other factor involved; No because different countries have different death rates at same % fat

Distinguish between positive and negative feedback. (4)

Positive feedback occurs when the feedback causes the corrective measures to remain turned on; So system deviates even more from original level; Negative feedback occurs when the feedback causes the corrective measures to be turned off; So system returns to normal level

The gene controlling coat colour has three alleles. The allele B gives black fur, the allele b gives chocolate fur and the allele bi gives cinnamon fur. ● Allele B is dominant to both allele b and bi. ● Allele b is dominant to allele bi. The breeder wanted to produce a population of cats that would all have chocolate fur. Is this possible? Explain your answer. (2)

Possible if parents homozygous; Don't know genotype of chocolate cat

During an action potential, the membrane potential rises to +40 mV and then falls. Use information from the graph to explain the fall in membrane potential. (3)

Potassium channels open; Potassium diffuses out; Sodium channels close

Order of reaction with respect to.....

Power to which the concentration of a particular species is raised in the rate equation

Give one advantage to farmers of attracting insects to their crops. (1)

Predators of pests of crop plants; Pollination of crops

Why at are primary, secondary and tertiary carbocation intermediates? Why are tertiary ones most likely to form?

Primary: 1 alkyl group Secondary: 2 alkyl groups Tertiary: 3 alkyl groups Tertiary carbocation intermediates are the most stable, as the positive inductive effect occurs within them to the greatest extent

What are primary, secondary and tertiary alcohols oxidised to by acidified potassium dichromate(VI) solution?

Primary: aldehydes and then carboxylic acids Secondary: ketones only Tertiary: not oxidised by it

Alkali

Produces hydroxide ions in aqueous solution

When walking along a street we barely notice the background noise of traffic. However, we respond to louder noises, such as the sound of a horn. From your knowledge of summation, explain this difference. (5)

Produces low-level frequency action potentials; Neurotransmitter insufficient to exceed threshold value to create a new action potential; Loud noises create higher frequency action potentials, neurotransmitter exceeds threshold value; Sufficient to trigger action potential in postsynaptic neurone; Example of temporal summation

Species X may change the environment so that it becomes more suitable for species Z. Use the graph to explain why. (2)

Produces shade; Species Z grows best in low light intensity

Give two ways in which a pathogen may cause disease when it has entered the body. (2)

Produces toxins; Damages cells

What is ammonification? (2)

Production of ammonium ions from ammounium containing compounds e.g. urea, proteins; By saprophytes

Give one advantage of using natural fertiliser produced in the digester rather than an artificial fertiliser. (1)

Production of artificial fertiliser is energy-consuming

Farmers sometimes give progesterone to sheep to prevent ovulation. Explain how progesterone prevents ovulation. (2)

Progesterone inhibits secretion of LH; LH stimulates ovulation

(Refer to June 2011 paper) The graph shows the concentrations of two hormones in the blood of an adult female pig over 25 days. Give one piece of evidence from the graph that this pig was not pregnant at 25 days. (1)

Progesterone returns to start

In column chromatography, suggest why propanone was present in samples of the eluent collected first (those with shorter retention times), whereas samples containing propan-2-ol were collected later

Propan-2-ol is more polar than propanone, so it has a greater affinity to the stationary phase.

What is glycerol's IUPAC name? What are fatty acids, structurally? How do fatty acids make esters?

Propane-1,2,3-triol Fatty acids are long chain carboxylic acids Fatty acids combine with glycerol to make esters

What is the role of the hydrolases: proteases, lipase and amylase? (3)

Proteases digest proteins to amino acids; Lipase digests lipids to glycerol and fatty acids; Amylase digests starch to maltose

Describe how nitrogen in compounds in a dead plant is made available for use by other plants. (6)

Proteins broken down; by saprophytes; ammonia formed; Ammonia converted to nitrate; by nitrifying bacteria; Nitrate can be absorbed by roots

Bronsted-Lowry Base

Proton Acceptor

Bronsted-Lowry Acid

Proton Donor

Bronsted Lowry acid

Proton donor

1 1.673 x 10^-27 kg +1 +1.60 x 10^-19 C

Proton relative mass, actual mass, relative charge and actual charge

In what form will amino acid residues exist after 2-aminopropanoic acid has been hydrolysed with 6M HCl acid and heat under reflux for 24 hours?

Protonated: +H3NCH(CH3)COOH

Azotobacter is a nitrogen-fixing bacterium. It produces the enzyme nitrogenase. The enzyme only works in the absence of oxygen. Azotobacter has a very high rate of aerobic respiration compared with bacteria that do not fix nitrogen. Suggest two advantages of the very high rate of aerobic respiration. (2)

Provides ATP for nitrogen fixation; Removes oxygen so nitrogenase works

Scientists investigated the effect of a pesticide called malathion on the survival of tadpoles of species of toads found in the USA. The scientists determined the LC50 for the tadpoles of each species over a 16-day period in an aquarium. The LC50 is the concentration of malathion that killed 50 percent of a population of tadpoles. The scientists also investigated whether the presence of a predator of tadpoles changed the effect of malathion. Suggest two advantages of using the LC50 to determine the effect of a pesticide. (2)

Provides a standard/benchmark; 2. Can compare (different pesticides/chemicals); 3. Does not kill all the tadpoles/organisms/population;

How does a Catalyst work?

Provides an alternative route with a lower Ea, so more particles have E>Ea, so the fraction of successful collisions increases

The burrows produced by earthworms improve drainage and aeration of the soil. Suggest how these burrows help to increase the rate of leaf decomposition. (2)

Provides oxygen for aerobic respiration; by bacteria

Outline the four pulmonary vessels, which chamber they're connected to and what blood they carry. (4)

Pulmonary vein - left atrium, carries oxygenated blood back from the lungs; Vena cava - right atrium, carries dexoygenated blood back from the tissues of the body; Aorta - left ventricle, carries oxygenated blood to the tissues of the body; Pulmonary artery - right ventricle, carries deoxygenated blood to the lungs, where its oxygen is replenished and its CO2 is removed

Complete the equation. Pulmonary ventilation = ....................× .................. (1)

Pulmonary ventilation = Tidal volume x Ventilation rate

The person's pulmonary ventilation changed between times C and D. Describe how the graph shows that the pulmonary ventilation changed. (3)

Pulmonary ventilation = tidal volume × breathing rate; Breathing rate increases between C and D; Tidal volume increases between C and D

(Refer to exam q) Figure 1 shows how the rates of metabolic heat generation and evaporative heat loss in a reptile change with environmental temperature. Each plot is the mean of several values. The vertical bars on the graphs represent the standard deviation about the mean. Explain why it is more useful to show the standard deviation rather than the range of values. (2)

Range just shows highest and lowest; SD less affected by extreme values

Reflexes are described as being rapid, automatic responses. Use the information in the diagram to explain those features of a reflex arc which result in the response being rapid and automatic. (4)

Rapid because only involves three neurones; Automatic because same pathway used each time; no thinking involved

What does the graph suggest about how a change in heart rate occurs when a person exercises? (1)

Rate increased by activity of sympathetic

Equilibrium

Rate of forwards reaction equals rate of reverse reaction and no net change in the concentration of reactants and products

Suggest an advantage of responding to high-level stimuli but not to low-level ones. (3)

Reacting to low-level stimuli can overload central nervous system; Organisms fail to respond to more important high-level stimuli; Which are more likely to represent danger

Explain collision Theory

Reactions only take place between particles that collide with sufficient energy energy is used to break the bonds in one or either of the reactant molecules

Whales spend most of their time deep in the sea but they come to the surface to breathe. When they are at the surface, scientists obtain small samples of their skin. The scientists find the base sequence in some of the DNA from these samples. The base sequence is different in each whale. You could use the information about the base sequence to estimate the size of the whale population by using mark-release-recapture. Explain why. (2)

Recording base sequence is like marking animal; Finding identical base sequence would show animal has been recorded before

In terms of rates, what is continuous monitoring?

Recording reactant or product amount/ concentration at regular time intervals to see how reaction rate changes over time

When the apple slices were transferred to nitrogen, the following biochemical pathway took place: Pyruvic acid ---> Ethanol (CH3-CO-COOH) ---> (CH3-CH2-OH) Use this pathway to explain the part played by reduced NAD when the apple slices were transferred to nitrogen.(2)

Reduced NAD reduces pyruvic acid; which requires hydrogen.

Display the reactions of ethanoyl chloride with each of cold water, methanol, ammonia and methylamine, naming all chemicals and listing how vigorous each reaction is. What observation can be made in each case?

Refer to big sheets Observation: toxic misty fumes (HCl gas)

The nettle leaves with the larger area had more chloroplasts, which produce ATP and reduced NADP. Explain how ATP and reduced NADP are used in the synthesis of glucose in the chloroplasts. (5)

Reduced NADP and ATP are used in light-independent reactions; To convert GP to triose phosphate; Reduced NADP supplies hydrogen atoms; ATP supplies energy; Some triose phosphate is converted to glucose;

Residual food intake (RFI) is the difference between the amount of food an animal actually eats and its expected food intake based on its size and growth rate. Scientists have selectively bred cattle for low RFI. Explain the advantage to farmers of having cattle with a low RFI. (2)

Reduced cost; due to more growth rate with same amount of food

Explain how the change in metabolic heat generation in a small mammal is brought about as environmental temperature rises. (3)

Reduced metabolic rate; Reduced respiration; Reduced physical activity

Coeliac disease is a disease of the human digestive system. In coeliac disease, the villi are damaged. Although people with coeliac disease can digest proteins they have low concentrations of amino acids in their blood. Explain why they have low concentrations of amino acids in their blood. (2)

Reduced surface area; So less absorption

Display the acid and base hydrolysis reactions of ethyl ethanoate with displayed formulae, naming chemicals and listing conditions.

Refer to big sheets

Display the hydrolysis of oils and fats to make soap, naming all chemicals involved

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the conversion of bromoethane to ethanol. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the conversion of bromoethane to ethylamine. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the conversion of bromoethane to propanenitrile. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the dehydration of ethanol. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the fermentation of glucose. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the reactions of ethanoyl chloride with each of cold water, methanol, ammonia and methylamine. Show all possible products and observations.

Refer to big sheets

Display the mechanisms and type of reaction and conditions needed for the reactions of propene with hydrogen bromide. Show all possible products and observations.

Refer to big sheets

Using displayed formulae, write the reactions for the oxidation of a primary alcohol to an aldehyde and the aldehyde to a carboxylic acid, using [O] as the oxidising agent and including conditions where necessary. Do the same for secondary alcohols.

Refer to big sheets

What is the functional group of the ester? Show the esterification of a general carboxylic acid and alcohol using displayed formulae, stating conditions required. What is another name for an esterification reaction? Why?

Refer to big sheets

Write equations for the separate reactions of ethanoic acid with sodium carbonate and sodium hydrogen carbonate, naming reactants and products.

Refer to big sheets

Display the mechanisms and equations and type of reaction and conditions needed for the reaction of ammonia with bromoethane. Show all possible products and observations. Why do you get a mixture of primary, secondary and tertiary amines and quaternary salts if you make amines via this method? Why does it end at quaternary salts? Draw mechanisms for the subsequent reactions, until you get to the quaternary ammonium salt.

Refer to big sheets The primary amine you produce first has a lone pair - it is a nucleophile. It reacts with any remaining halogenoalkane in a nucleophilic substitution reaction. These can continue until you get an ammonium salt, which can't react any further as it has no lone pair. Refer to big sheets

Display the reaction for the formation of ethanoic anhydride - what is its structural formula?

Refer to big sheets (CH3CO)2O

Display the reactions of ethanoic anhydride with each of cold water, methanol, ammonia and methylamine. What differences are there between the acid anhydride reactions and the ethanoyl chloride reactions?

Refer to big sheets Acid anhydride reactions are less vigorous and produce carboxylic acid instead of HCl gas.

Using displayed formulae, write the reactions for the reduction of an aldehyde and a ketone, using [H] as the reducing agent and including conditions where necessary. Draw the mechanisms for these reactions. Where do the H+ ions come from?

Refer to big sheets H+ ions from water, usually, or sometimes a weak acid

Using displayed formulae, write the reactions for the reduction of an aldehyde and a ketone, using [R] as the reducing agent and including conditions where necessary. Draw the mechanisms for these reactions. Where do the H+ ions come from?

Refer to big sheets H+ ions from water, usually, or sometimes a weak acid

Display the mechanism that shows how the halogen carrier AlCl3 makes a general acyl chloride a stronger electrophile. Why does it become a stronger electrophile? Display the subsequent reaction of the acyl chloride carbocation with a benzene ring. Display a reaction that occurs next. What conditions are needed?

Refer to big sheets It gains a positive charge Refer to big sheets Refer to big sheets Reactants heated under reflux in a non-aqueous solvent (like dry ether).

Display the mechanisms and type of reaction and conditions needed for a butanone and cyanide to make 2-hydroxy-2-methylbutanenitrile. Show all possible products and observations. What type of molecule is the product?

Refer to big sheets Product is a hydroxynitrile

Draw the 2 possible skeletal formulae for benzene. Why is one of the skeletal formulae misleading?

Refer to big sheets The skeletal formula involving alternating single and double bonds is misleading, as electrons are spread out evenly around the ring.

Show the dissociation of a carboxylic acid via displayed formulae, naming reactants and products. Why is it a weak acid?

Refer to big sheets. Most molecules don't dissociate, so the equilibrium lies to the left

In this investigation, the higher the concentration of sucrose in a rat's mouth, the higher the frequency of nerve impulses from each taste receptor to the brain. If rats are given very high concentrations of sucrose solution to drink, the refractory period makes it impossible for information about the differences in concentration to reach the brain. Explain why. (2)

Refractory period limits the frequency of nerve impulses; When maximum frequency reached, all higher concentrations of sucrose seem the same

Temperature

Related to average Kinetic Energy of particles in a system, particles move faster and Kinetic Energy increases so temperature goes up. Temperature is independent of amount of substance.

(Refer to exam q) Figure 2 shows the relationship between metabolic heat generation and evaporative heat loss in a small mammal. How is the relationship between heat generation and evaporative heat loss in a mammal different from that in a reptile? (1)

Relationship is inverse

On a G.C. chromatogram, what does the relative area under each peak tell you? What are applications of gas chromatography?

Relative amount of each component present in a mixture. Finding alcohol levels in blood or urine (results are accurate enough to be used as evidence in court), and finding proportions of various esters in oils used in paints (so picture restorers know what paint was originally used).

Average mass of 1 atom of an element divided by 1/12 the mass of a carbon-12 atom

Relative atomic mass

What is relative isotopic mass?

Relative isotopic mass is the mass of an atom of an isotope of an element on a scale where an atom of Carbon-12 is exactly 12.

Average mass of 1 molecule divided by 1/12 the mass of a carbon-12 atom

Relative molecular mass

Explain how a person breathes out. (4)

Relaxation of intercostal muscles moves ribs down and in; Relaxation of diaphragm muscles causes it to return to its dome shape; There is a decrease in volume of thorax and increase in pressure of air; Air moves out down pressure gradient

ATP is useful in many biological processes. Explain why. (4)

Releases a small amount of energy at a time; It is broken down in one step; Immediate source of energy; Can be reformed

There are lots of organelle G in this cell. Explain why. (2)

Releases energy; Which is needed for active transport

In an investigation, scientists transferred slices of apple from air to anaerobic conditions in pure nitrogen gas. They measured the rate of carbon dioxide production. The scientists kept the temperature constant throughout the investigation. Explain how a decrease in temperature would affect the rate of carbon dioxide production. (2)

Respiratory reactions are controlled by enzymes; Rate decreases as there is less kinetic energy and so fewer enzyme substrate complexes are formed.

Explain what the results from group A suggest about the factors controlling the behaviour of winged termites. (3)

Respond to gravity; Antennae involved; Doesn't respond to light as their eyes are covered

Suggest two advantages to a plant of having roots that respond to gravity by growing in the direction of its pull. (Sum)

Response ensures that roots grow downwards into the soil, thus anchoring the plant firmly and bringing it closer to water, needed for photosynthesis.

(Refer to exam q) Explain what the results of cutting the sympathetic and parasympathetic nerves demonstrate about the control of resting heart rate. (3)

Resting heart rate controlled by both divisions; Heart rate changes when parasympathetic/sympathetic nerve cut; Larger change in heart rate when parasympathetic nerve is cut

What is myocardial infarction? (3)

Results from a blockage in the coronary arteries; Reducing oxygen supply to the heart muscle; So the heart muscle is unable to respire

What does Rf stand for in chromatography? What determines Rf?

Retardation factor Rf depends on attraction of solute to stationary phase and mobile phase. Greater attraction (or affinity) of solute to mobile phase means greater Rf, stationary phase, smaller Rf. If solvent is less polar than stationary phase and solute is polar, it'll be less attracted to the solvent and more attracted to the stationary phase. In this case, greater polarity of solute means smaller Rf value.

Name the substance which combines with carbon dioxide in a chloroplast. (1)

Ribulose bisphosphate

Two pieces of information from the graph, other than the change in progesterone concentration, show that ovulation took place at the time indicated. Explain how. (4)

Rise in oestrogen; Associated with follicle growth; Surge in LH before ovulation; LH stimulates ovulation

(Refer to June 2012 paper) Scientists compared the results of three investigations, A, B and C. These investigations were into the effect of drinking different amounts of alcohol on the risk of developing heart disease. The graph shows the results of these investigations. Describe the relationship between increasing the number of alcoholic drinks per day and the risk of heart disease in investigation A. (2)

Risk decreases, then increases; Risk increases from 2 drinks per day

(Refer to exam q) The table shows some information about the incidence of high blood pressure and heart attacks in the UK. Use the pattern of data in the table to describe two similarities between males and females (2)

Risk of: High blood pressure increases with age; Heart attack increases with age

What hazards to potassium cyanide pose? How can these risks be reduced?

Risks: -It is irritant -It is dangerous if ingested or inhaled -Reacts with moisture to produce hydrogen cyanide, a highly toxic gas Precautions: -Wear gloves -Wear safety goggles -Wear a lab coat -Perform experiment in a fume cupboard

Ore

Rocks with a high enough percentage of a metal to be extracted commercially

Explain how two adaptations of their leaves reduce water loss from xerophytes. (2)

Rolled leaves reduce surface area for evaporation; Stomata in sunken pits to reduce diffusion gradient

Describe how water is taken up by root hairs and reaches the xylem in the root. (6)

Root hair cells have lower water potential than soil; Due to uptake of ions by active transport; So water enters root hair cells by osmosis; Passes along apoplast pathway; Through water filled spaces of cell walls; And passes along symplast pathway; Through cytoplasm of cells

Explain why there is twice the amount of glycerate 3-phosphate as ribulose bisphosphate when the carbon dioxide concentration is high. (1)

RuBP combines with carbon dioxide to produce 2 x GP

Explain why there is twice the amount of glycerate 3-phosphate as ribulose bisphosphate when the carbon dioxide concentration is high. (1)

RuBP combines with carbon dioxide to produce 2 × glycerate 3-phosphate

The research team set the traps immediately after using the hair tubes. Explain why setting the traps immediately after using the hair tubes would make comparisons between the two methods more reliable. (2)

Rules out differences due to changes in population; That could be produced by births, deaths, migration etc

(Refer to exam q) The diagram shows the pathways in the heart for the conduction of electrical impulses during the cardiac cycle. Name structure A. (1)

SAN

Describe how a heartbeat is initiated and coordinated. (5)

SAN sends wave of electrical activity across atria causing atrial contraction; Non-conducting tissue prevents impulses reaching the ventricles; AVN delays impulse whilst ventricles fill; AVN sends a wave of electrical activity down Bundle of His; Causing ventricles to contract from base up

The heart controls and coordinates the regular contraction of the atria and ventricles. Describe how. (5)

SAN sends wave of electrical activity across atria; causing atrial contraction; Non-conducting tissue between atria and ventricles prevents the impulse crossing to the ventricles; AVN delays electrical activity allowing ventricles to fill before they contract; The ventricles contract from apex upwards

What happens in gas chromatography-mass spectrometry (GC-MS) and why is it used? What are 2 advantages of GC-MS over normal GC?

Sample is separated via gas chromatography and then separated components are fed into a mass spectrometer, which produces a mass spectrum for each component, which can be used to identify each one and show what the original sample consisted of. 1. Components separated out my chromatography can be positively identified, which is impossible from a chromatogram alone. 2. Computers can match up the mass spectrum for each component of the mixture against a database, so the whole process can be automated.

Much of Indonesia is covered with forest. Large areas of forest have been cleared and planted with oil-palm trees to be used in the production of fuel. In these forests, nitrogen in dead leaves is made available to growing plants by the action of bacteria. Describe the role of bacteria in making the nitrogen in dead leaves available to growing plants. (5)

Saprophytes; digest nitrogen-containing substances; to produce ammonia; Ammonia converted to nitrate ions; by nitrifying bacteria; in an oxidation reaction

What difference is found between the original Bohr atom model and the refined Bohr model?

Scientists discovered that not all electrons in a shell have the same energy, so it was refined to include sub shell's.

The ratio of the dry biomass of animals to the dry biomass of seaweeds is always a lot less than one. Explain why. (2)

Seaweeds are producers; Loss of energy between trophic levels

Selective breeding can be used to produce cows with desirable features. This involves mating cows with bulls. Suggest how a bull is selected to increase the probability of producing cows with a high milk yield. (1)

Select a bull whose mother produced a high milk yield

The actual diameter of organelle Y is 0.5μm. Calculate the magnification of the diagram. Show your working. (2)

Sensible measured diameter ÷ actual (0.0005 mm) = 30,000

The average efficiency of energy transfer between producers and primary consumers in pyramids of energy is around 10 %. Suggest why the efficiency of energy transfer from producers to primary consumers in this food web is higher than 10 %. (2)

Single-celled producers are more digestible; All of producer eaten

Disadvantages of fermentation of Glucose to produce ethanol

Slow batch process, stopping and starting high production costs ethanol needs to be purified using fractional distillation depletes land used for growing food crops

How do slow-twitch fibres differ from fast-twitch fibres in the way they function? (6)

Slow-twitch fibres: Contract more slowly; Provide less powerful contractions; Over a longer period; Fast-twitch fibres: Contract more rapidly; Produce powerful contractions; For a short period

Rate determining step

Slowest step in the overall equation that governs the rate of the chemical reaction

Snow geese fly north to the Arctic in the spring and form breeding colonies. Different colonies form at different latitudes. The greater the latitude, the further north is the colony. The further north a breeding colony forms, the colder the temperature and the greater the risk of snow. There is a positive correlation between the size of snow geese and how far north they breed. A large size results in snow geese being adapted for breeding in colder conditions. Explain how. (2)

Small surface area to volume ratio; And so lose less heat to the environment

Heat from respiration helps mammals to maintain a constant body temperature. Use this information to explain the relationship between body mass and oxygen uptake shown in the graph. (3)

Smaller animals have larger surface area to volume ratio; and so lose more heat per gram of tissue; They respire more; and oxygen is used in respiration

Identify three lifestyle factors that contribute to cancer. (3)

Smoking; Diet; Sunlight

Some foods contain substances called flavenoids. Flavenoids lower blood cholesterol concentration and reduce the risk of developing coronary heart disease. Some types of dark chocolate have a high concentration of flavenoids. One group of scientists investigated the effect of eating dark chocolate on the risk of developing coronary heart disease. The scientists randomly divided healthy volunteers into two groups. Every day one group was given dark chocolate containing flavenoids to eat. The other group acted as a control. The scientists measured the diameter of the lumen of the main artery in the 10 arms of the volunteers every week. At the end of a month, the diameter of the lumen of the main artery in the arm of the volunteers who had eaten dark chocolate containing flavenoids had increased. The scientists used healthy volunteers in this investigation. Why was it important that the volunteers were healthy? (1)

So that the lumen diameter was not affected by other factors

Why do alveoli contain elastic fibres? (2)

So that they can stretch as they fill with air when breathing in; and can recoil during breathing out to expel the CO2-rich air

Why are the bacteria in the tuberculosis vaccine weakened before they are injected? (1)

So they are less likely to cause the symptoms of tuberculosis

The mixture used to make the ORS contains glucose. Give one other substance that must be present in the mixture. (1)

Sodium ions

What is the particle structure in solids liquids and gases?

Solids - Its particles are very close together giving it a high density and making it incompressible. The particles vibrate about s fixed point with no free movement Liquids - Have a similar density to a solid with free moving particles allowing it to flow Gas - the particles have a high amount of energy and are much further apart. Particles have free movement with little attraction between them.

Group 2 Sulphates

Solubility decreases down the group ppt formation equations are: XCl2 + Na2SO4 → 2NaCl + XSO4(s) or X2+ + SO4 2- → XSO4(s)

What colour change occurs when you add Cl2 to KBr? Why? What about Cl2 to KI? What about Br2 to KI?

Solution turns orange, as orange Br2 forms. Solution turns brown, as brown I2 forms. Solution turns brown as brown I2 forms.

Scientists have suggested that siRNA may be useful in treating some diseases. Suggest why siRNA may be useful in treating disease. (2)

Some diseases are genetic; siRNA will stop product of this gene

Describe the reasons for the low efficiency of energy transfer through ecosystems. (5)

Some light is not of appropriate wavelength; Some light misses chloroplasts; Heat loss in consumers; Energy loss via respiration in consumers; Loss via excretion

Give two reasons why all the light energy reaching the producers cannot be used in photosynthesis. (2)

Some light misses chloroplasts; Only certain wavelengths of light used

How do people develop lactose intolerance? (4)

Some people produce little or no lactase; So there is not enough to digest all the lactose they consume; When the undigested lactose reaches the small intestine microorganisms break it down, giving rise to a large volume of gas by respiration; This results in bloating, nausea, cramps etc

What is the solubility of the covalent bonds like?

Some simple covalent compounds dissolve in water depending on how polarised the molecules are

Apart from respiration, give three uses of ATP in a liver cell. (3)

Source of energy; Active transport; Cell division

(Refer to Jan 2010 paper) The graph shows the effects of light intensity on the rate of photosynthesis of three species of tree, X, Y and Z. Each of these species occurs at a different stage in succession. Species X is the first tree to become established in the succession. Use the graph to explain why it is likely to become established earlier in the succession than Y or Z. (3)

Species X has high rate of photosynthesis at high light intensity; Species X grow fastest at high light intensities; Will outcompete other species Y/Z

Biological washing powders often contain a number of different enzymes. This enables them to remove a wider range of stains from clothes. Explain why a number of enzymes are required to remove a wider range of stains. (3)

Stains are caused by different substances; Enzymes are specific; So other substrates cannot fit their active site

The standard enthalpy of hydrogenation of cyclohexane is -120kJmol^-1; that of benzene is -208kJmol^-1. How does this show that benzene is actually more stable than the theoretical compound cyclohexa-1,3,5-triene?

Standard enthalpy of hydrogenation of cyclohexa-1,3,5-triene would be 3*(-120kJmol^-1) = -360kJmol^-1, as cyclohexa-1,3,5-triene would accept 3 hydrogen molecules, not just 1. Therefore, standard enthalpy of hydrogenation of benzene is 152kJmol^-1 less exothermic than that of cyclohexa-1,3,5-triene would be. The same bonds form in both cases, so the same amount of energy is released in the hydrogenation of both types of molecule, therefore, more energy must be absorbed to break benzene's ring of delocalised electrons than to break cyclohexa-1,3,5-triene's double bonds, so benzene must be more stable than cyclohexa-1,3,5-triene.

(Refer to Jan 2006 paper) Several small pieces of a saprophytic fungus were placed on a starch agar plate. After 48 hours the iodine solution was poured over the starch agar. The result is shown in the diagram below. Explain why there is a clear area around most of the pieces of fungus. (2)

Starch broken down; by amylase

(Refer to Jan 2013 paper) Scientists investigated how effective two oral rehydration solutions, A and B, were in treating patients with diarrhoea caused by cholera. - Solution A contained glucose. - Solution B was identical to A, except that glucose was replaced by starch. The graph shows their results. The water potential of solution B was higher (less negative) than the water potential of solution A. Explain why. (1)

Starch is not very soluble

The concentration of glucose in the blood rises after eating a meal containing carbohydrates. The rise is slower if the carbohydrate is starch rather than sucrose. Explain why. (3)

Starch needs to be digested to maltose by amylase; Maltose then needs to be digested to glucose by maltase; Whereas digestion of sucrose is a single step

Explain how the structures of the stomach wall and the ileum wall are related to the functions of these organs. (6)

Stomach: Extra muscle layers; To create a churning action to break down food; Glands; Produce mucus to protect stomach wall; Ileum: villi; create a larger surface area for absorbing the products of digestion

The results that the student obtained for the leaves in set B were different from those for set A. Suggest an explanation for this difference. (2)

Stomata on the upper surface are covered; So there is less evaporation

Marram grass is a pioneer species that grows on sand dunes. It has long roots and a vertically growing stem that grows up through the sand. Sand dunes are easily damaged by visitors and are blown by the wind. Planting marram grass is useful in helping sand dune ecosystems to recover from damage. Use your knowledge of succession to explain how. (2)

Stops sand shifting; Makes conditions less hostile

A horse was kept in the field from March to October. During the summer months, the horse was able to eat more than it needed to meet its minimum daily requirements. Suggest how the horse used the extra nutrients absorbed. (2)

Stored as fat; Used for growth;

If, for a certain reactant, a concentration-time graph shows a straight line, a quadratic curve or a cubic curve, what is the order of the reaction with respect to that reactant?

Straight line: zero Quadratic: first Cubic: second

Explain how a Pacinian corpuscle produces a generator potential in response to external pressure. (3)

Stretches membrane; Sodium ion channels open; Sodium ions enter causing depolarisation

The aorta has many elastic fibres in its wall. An arteriole has many muscle fibres in its wall. Explain the importance of elastic fibres in the wall of the aorta. (2)

Stretches under high pressure when the ventricle contracts; Recoils under low pressure when the ventricle relaxes

(Refer to Jan 2011 paper)The table shows the cardiac output and resting heart rate of an athlete before and after completing a training programme. Calculate the athlete's stroke volume after training. Show your working. (2)

Stroke Volume = Cardiac Output / Heart Rate; = 90.9

For a strong acid/ strong base pH curve, what does pH range from? Strong acid/ weak base? Weak acid/ strong base? Weak acid/ weak base?

Strong acid/ strong base: pH ranges from 1 to 13 Strong acid/ weak base: pH ranges from 1 to 9 Weak acid/ strong base: pH ranges from 4 to 13 Weak acid/ weak base: pH ranges from 4 to 9

What are strong Brønsted-Lowry acids/bases? Give examples

Strong acid: they dissociate almost completely in water, so nearly all the protons are released. HCl Strong base: they ionise almost completely in water. NaOH

What do you use to find a strong base's pH? What do you use to find a weak acid's pH?

Strong base: Kw Weak acid: Ka

Molecules with the same molecular formula but different structural formulae: -Chain isomers (different arrangements of the carbon skeleton) -Positional isomers (same carbon skeleton, atoms or groups attached in different places) -Functional group isomers (different functional groups)

Structural isomers? Give the 3 types

What limits the rate of this reaction between points A and B? Give the evidence from the graph for this. (2)

Substrate concentration; Because as substrate concentration increases, rate increases

(Refer to June 2013 paper) Hyperthermia is a condition in which a person's body temperature is above 37.5 ºC. This happens when a person's body produces or absorbs more heat than it loses to the environment. Doctors recruited healthy volunteers. At a room temperature of 20 ºC, the doctors measured each volunteer's: - body temperature - rate of oxygen consumption - rate of carbon dioxide production. Each volunteer then put on a suit that covered the whole body. Water at 38 ºC was circulated through pipes in the suit. This caused the volunteer to develop hyperthermia. The doctors' results are shown in the table. Explain one way in which a suit with water circulating in it at 38 ºC causes hyperthermia. (2)

Suit prevents loss of sweat; So heat of evaporation not lost

Suggest an explanation for the change in the slope of the graph for evaporative heat loss at the point marked X. (1)

Sweating increases

(Refer to June 2010 paper) Termites are insects. Some species live in colonies in the soil. Although most termites are wingless, winged termites are sometimes produced. The winged termites fly from the soil, mate and start new colonies. A scientist studied the behaviour of winged termites. He divided these termites into three groups. ● Group A had their eyes covered. ● Group B had their antennae removed. ● Group C was the control group. He put individual winged termites on a sloping board that was illuminated from one side. The diagram shows the direction of movement of a typical termite from each of the three groups. What type of behaviour was shown by the termite from group B? Give the evidence for your answer. (2)

Taxis; because moves towards light

Distillation

Technique that separates organic product from reacting mixture - used for the oxidation of primary alcohols to aldehydes

When you place your hand on a hot object, your involuntary response is to pull your hand away. Describe the reflex arc which coordinates this process. (6)

Temperature receptors in skin detect the stimulus (heat from the object); This creates a nerve impulse in a sensory neurone; Sensory neurone passes the nerve impulse to the spinal cord; Intermediate neurone links the sensory neurone to a motor neurone in the spinal cord; Motor neurone carries the nerve impulse from the spinal cord to an effector; The effector is the muscle in the arm which contracts to remove hand

What is the only thing that affects Kp? How?

Temperature: if temperature rises and forward reaction is endothermic, equilibrium shifts right, thus increasing products' partial pressures and reducing that of reactants, increasing Kp.

What is the only thing that affects Kc? How?

Temperature: if you change the temperature and product and reactant concentrations increase and decrease respectively, Kc rises.

Suggest two abiotic factors that could affect the burrowing behaviour of earthworms. (1)

Temperature; Water

Students investigated the effect of pH on the activity of the protease. • The students used agar plates containing protein. The protein made the agar cloudy. • They made four wells of equal size in the agar of each plate. • They added a drop of protease solution to each of the wells. The protease solution in each well was at a different pH. • The students incubated the agar plates for 4 hours at a constant temperature. The diagram shows the agar plates after they were incubated and the pH of the protease solution in each well. (Refer to June 2011 paper) How should the students make sure that the pH of the protease solution did not change? (1)

Test pH at intervals

What is meant by the high specificity of enzymes? Why does this high specificity exist? What is the causing model called? What does it mean for active sites to be stereospecific, and why is there stereospecificity?

That enzymes only work with specific substrates - usually only one. For the enzyme to work, the substrate has to fit into its active site. If the substrate's shape doesn't match the active site's shape, the reaction won't be catalysed. This is called the 'lock and key' model. Enzymes are made of amino acids, so they contain chiral centres, so they'll only work on one enantiomer of a substrate. The other will not fit properly in the active site, so the enzyme can't work on it properly.

Why can't you easily hydrolyse a polymer with repeating unit -CH2CF2CF2CF(CH3)-?

The C-C and C-F bonds are too strong?

Hess's Law

The Enthalpy Change for a chemical reaction is independent of the route taken

Bond Dissociation Enthalpy

The Enthalpy Change needed to break 1 mole of a covalent bond with all species in the gaseous state The energy given out is the same as the amount taken in when the bond is formed always endothermic, ∆H is positive ∆H = ∑(Bonds Broken) - ∑(Bonds Formed)

Mean Bond Enthalpy

The Enthalpy Change needed to break a bond, averaged over different molecules

Standard Molar Enthalpy of Formation

The Enthalpy Change when 1 mole of a substance is formed from it's constituent elements under standard conditions. With all reactants and products in their standard states ∆Hc = ∑∆Hf(Products) - ∑∆Hf(Reactants)

How does succession lead to more complex food webs? (3)

The abiotic environment becomes less hostile, e.g. soil froms with plentiful nutrients; This leads to a greater number of habitats; This leads to increased biodiversity as different species occupy these habitats

What is relative atomic mass?

The average mass of an atom of an element compared to one twelfth of the mass of an atom of carbon 12.

How is pulmonary tuberculosis transmitted? (3)

The bacteria is transmitted through the air by droplets released when infected people cough, sneeze, talk etc and inhaled; Takes close contact with an infected person over a period of time rather than a short encounter; Also transmitted through milk

Rate of Reaction

The change in concentration of either reactants or products per unit time

Explain why changing one of the amino acids that make up the active site could prevent the enzyme from functioning. (3)

The changed amino acid may no longer bind to the substrate; so the substrate no longer fits the active site; so an enzyme-substrate complex cannot be formed

What is the quaternary structure of a protein? (1)

The combination of a number of different polypeptide chains and associated prosthetic groups into a large, complex protein molecule.

State the source of the energy for the extraction of iron in a blast furnace

The combustion of coke, air is blown in C + O2 → CO2 CO2 + C → 2CO

Enthalpy of formation

The enthalpy change when one mole of a substance is formed from its elements, with all substances in their standard states under standard conditions

The graph shows the relationship between the concentration of a substance outside a cell and the rate of entry of this substance into the cell. Explain the evidence from the graph that this substance is entering the cell by facilitated diffusion and not by simple diffusion. (2)

The curve levels off above a certain external concentration of substance; As channel proteins are saturated with molecules and no more can be carried

How does metallic bonding explain metals ability to conduct electricity?

The delocalised electrons can pass kinetic energy to each other, making them good thermal conductors. Metals are good electrical conductors because the delocalised electrons can carry a current.

Where does glucose come from? (3)

The diet - carbohydrates such as starch, maltose, lactose and sucrose are broken down into glucose; From the breakdown of glycogen (glycogenolysis) in the liver and muscle cells; From gluconeogenesis, which is the production of glucose from glycerol and amino acids

What is an empirical formula?

The empirical formula gives the smallest whole number ratio of atoms in a compound.

What is the vertical part of the acid/base graph called? Which graph doesn't have an explicitly vertical part?

The end point or equivalence point Weak acid/ weak base curve doesn't have an explicitly vertical part?

What is standard enthalpy of formation?

The enthalpy change when 1 mole of a compound in its standard state is formed from its constituent elements in their standard states under standard conditions

What is standard enthalpy of combustion?

The enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions, with all reactants and products in their standard states

Lattice enthalpy of dissociation

The enthalpy change when one mole of a solid ionic compound is broken up into its constituent elements in the gas phase

Lattice enthalpy of formation

The enthalpy change when one mole of a solid ionic compound is formed from its constituent elements in the gas phase

Enthalpy of solution

The enthalpy change when one mole of a solid ionic substance is dissolved in enough water so that the ions are separated and do not interact with each other

What happens during the deflection stage of mass spectrometry?

The fast moving ions pas into a string magnetic field, deflecting the ions into a curved path. The degree of deflection depends on the Mass/charge ratio (m/z). Ions with with a high m/z ratio are deflected the least (they're heavier). The strength of the magnet is gradually increased so that ions with different m/z ratios are deflected towards the detector.

What is the first ionisation energy?

The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.

Through which two systems can pathogens enter the body? (2)

The gas-exchange system and the digestive system.

Explain how the cells lining the trachea and bronchus protect the alveoli from damage. (3)

The goblet cells produce mucus that traps dirt particles and bacteria in air breathed in; The cilia move this mucus up the trachea and into the stomach; The dirt and bacteria could cause infection in the alveoli

How does the diameter of an axon affect the speed of a nerve impulse? (2)

The greater the diameter of an axon, the faster the speed of conductance; due to less leakage of ions from a large axon

What is an atom's environment in a molecule? What standard substance is the energy of different frequencies absorbed by nuclei in different environments measured relative to? Why is this substance used?

The groups of atoms it is bonded to. Tetramethylsilane (TMS), Si(CH3)4. This molecule contains 12 hydrogen atoms in identical environments, so it produces a single absorption peak, well away from most other absorption peaks. Also, TMS is inert (so it doesn't react with the sample and affect results), it's non-toxic and it's volatile (so it's easy to remove from the sample).

How does temperature affect the speed of a nerve impulse? (5)

The higher the temperature the faster the nerve impulse; Sodium-potassium pump uses active transport; Which requires energy from ATP from respiration; Respiration is enzyme-controlled; More kinetic energy so more enzyme-substrate complexes formed and faster diffusion

How does nuclear charge affect ioniation energy?

The more protons that are in the nucleus, the more positively charged the nucleus is and the stronger the attraction for the electrons

How does metallic bonding explain the melting points of metals?

The number of delocalised electrons per atom affects the melting point. The more there are, the stronger the bonding will be and the higher the melting point. The size of the metal ion and the lattice structure also affect the melting point.

What does the number of main peaks on 1 carbon-13 NMR spectrum tell you about a molecule? Why are carbon-13 NMR spectra usually much simpler than hydrogen-1 NMR spectra?

The number of different carbon environments the molecule has. The former have fewer, sharper peaks.

What do splitting patterns on a hydrogen-1 NMR spectrum tell you? What does an integration trace show you on a hydrogen-1 NMR spectrum? How do you use it? What is the ratio shown by the integration pattern called?

The number of peaks in a splitting pattern equals one plus the number of hydrogen atoms bonded to the neighbouring carbon atom. The relative areas of each peak. The increase in height of the trace at each main peak is proportional to the areas under each peak. The integration ratio.

What is meant by an amino acid's isoelectric point? Why do different amino acids have different isoelectric points?

The pH at which the average overall charge on the amino acid is zero. They have different R-groups, and the isoelectric point is dependent upon the nature of the R-group.

What happens during the acceleration stage of mass spectrometry?

The positive ions are attracted by negatively charged plates in an electric field which accelerates the ions and focuses the beam.

What happens during the detection stage of mass spectrometry?

The positive ions hit an electrically charged plate/ the current produced is then amplified and recorded as a 'peak'. Each peak is a measure of the relative abundance of each ion.

In gas chromatography, what is the retention time? What does the retention time depend on? Why and how can you use retention times to identify the components of a mixture?

The time elapsed between each component of the mixture being injected into the tube and being detected/recorded at the other end (all components injected simultaneously, as they're yet to be separated). On how much time the component spends moving along with the carrier gas, and how much time it spends stuck to the viscous liquid. Each separate substance has a unique retention time - if you want to know if a mixture contains octane, run a sample of the mixture through the system and then run a sample of pure octane, and compare positions of peak on the G.C. chromatogram in terms of retention times.

Oxidation state

The total number of electrons an element has donated or accepted.

What is the mass number?

The total number of protons and neutrons in the nucleus of an atom

What is the all-or-nothing principle? (Sum)

There is a particular level of stimulus that triggers an action potential. At any level above this threshold, a stimulus will trigger an action potential that is the same size regardless of the size of the stimulus. Below the threshold, no action potential is triggered.

An increase in temperature causes an increase in carbon input. Explain why. (2)

There is an increase in photosynthesis; because enzyme activity increases

The percentage of white snow geese in these colonies changed over the period shown in the table. Use your knowledge of climate change to suggest an explanation. (2)

There is less snow due to global warming; White geese decreasing as less well camouflaged

Efficient exchange of substances in the capillaries is linked to the rate of blood flow. Explain how. (1)

There is more time for exchange of substances

Why can't you use an indicator to determine the end point of a weak acid/ weak base titration?

There's no sharp pH change

One effect of getting into a cold shower is a reduction in the amount of blood flowing through the capillaries near the surface of the skin. Explain how the cold water causes this response. (5)

Thermoreceptors in skin; impulses via neurones to; hypothalamus; temperature centre in hypothalamus; causes constriction of arterioles

Suggest one reason why oral antibiotics are not normally used to treat gastroenteritis and other diarrhoeal diseases. (2)

These diseases cause vomiting an diarrhoea; so antibiotic is unlikely to remain in the body long enough to be absorbed

Why is the volume of oxygen that has to be absorbed and the volume of CO2 that has to be removed large in mammals? (2)

They are relatively large organisms with a large volume of living cells; They maintain a high body temperature and therefore have high respiratory rates

Why are amino acids amphoteric? Give the common name and the IUPAC name of the only achiral amino acid molecule? Draw the displayed formula for a general amino acid.

They contain a basic amino group (NH2) and an acidic carboxyl group (COOH). Glycine (aminoethanoic acid) 7. Refer to big sheets

How do greenhouse gases contribute to global warming?

They enter the atmosphere and absorb lots of infrared radiation (heat) and emit some back towards Earth, keeping it warm.

Why can you separate and identify the amino acids in a mixture using thin-layer chromatography? How do you work out the Rf value in thin-layer chromatography? Where must you measure between when measuring the distance moved by the spot? How can you make spots of amino acids visible in thin-layer chromatography?

They have different R groups, meaning they'll have different solubilities in the same solvent - amino acid molecules with shorter, smaller R groups (or a hydrogen atom in its place) are the most soluble. Rf = x/y = (distance traveled by spot)/(distance traveled by solvent) The point of origin to the middle of the spot - By spraying ninhydrin solution on the plate, making the spots purple, or - By using a special plate with fluorescent die added to it, which glows when UV light is shone on it

Why don't catalysts affect rate of equilibrium? What do they do in terms of equilibrium?

They increase forward and reverse reaction rates by the same amount, so equilibrium position is unchanged. However, they allow equilibrium to be reached faster.

How do enzymes speed up reactions? (1)

They lower the activation energy, allowing reactions to take place at a lower temperature than normal.

How may drugs effect synapses? (2)

They stimulate the nervous system by creating more action potentials in postsynaptic neurones; They inhibit the nervous system by creating fewer action potentials in postsynaptic neurones

The rate of carbon dioxide production was higher when the apple slices were in nitrogen than when they were in the air. Explain why. (3)

They were respiring anaerobically; Anaerobic respiration produces less ATP; More anaerobic respiration must occur to produce the same amount of ATP, so more carbon dioxide is produced

What were CFCs once used for? Why are they now banned? What is used instead?

They were used as coolant gas in fridges, as solvents and as propellants in aerosols CFCs' advantages can't outweigh environmental problems they cause (ozone decomposition) HFC (hydrofluorocarbons, without chlorine atoms) and hydrocarbons are used instead

There are differences in the properties of the cuticle on the upper and lower surfaces of leaves. Suggest how these differences in the cuticle might explain the differences in rates of uptake of NAA by the two surfaces. (2)

Thick cuticle on upper surface; So shorter diffusion pathway on lower surface

Explain why people with miner's lung have a lower concentration of oxygen in their blood. (1)

Thicker alveolar wall so longer diffusion pathway

How are fast-twitch fibres adapted for their function? (4)

Thicker and more numerous myosin filaments; High concentration of enzymes involved in anaerobic respiration; Store of phosphocreatine, which generates ATP from ADP in anaerobic conditions; So adapted for anaerobic respiration due to a build-up of lactic acid and more intense exercise

The maximum pressure in the left ventricle is higher than the maximum pressure in the right ventricle. What causes this difference in pressure? (1)

Thicker muscle in the left ventricle

Give one advantage of using a SEM rather than a TEM. (1)

Thin sections do not need to be prepared

Describe two adaptations of the structure of alveoli for efficient gas exchange. (2)

Thin walls; Total surface area is large

What does TLC stand for? What stationary phase can be used in TLC? Why should you wear gloves when handling the apparatus used in TLC? Why should you place the apparatus in a fume cupboard after the chromatography, before making your observations? What is the resulting apparatus in TLC called?

Thin-layer chromatography A thin layer of silica (silicon dioxide) or alumina (aluminium oxide) fixed to a glass or metal plate. To avoid contamination of the experiment by substances on your hands. So it can dry without toxic or flammable fumes escaping into the room. A chromatogram

A scientist investigated ATP production in a preparation of isolated mitochondria. He suspended the mitochondria in an isotonic solution and added a suitable respiratory substrate together with ADP and phosphate. He bubbled oxygen through the preparation. Why was the solution in which the mitochondria were suspended isotonic? (1)

To prevent damage to mitochondria caused by osmosis

Explain why the scientists kept the suspension ice cold during the process. (1)

To prevent enzyme activity

Why does high blood pressure increase the risk of coronary heart disease? (2)

To resist the higher pressure, walls of the arteries become thickened and may harden; restricting flow of blood to the heart muscle

What is gas chromatography used for? What is the stationary phase used and what is it packed into? What is the mobile phase used? Draw diagram of apparatus used in GC.

To separate out volatile liquids so you can identify them. Solid or solid coated by viscous liquid, like oil, packed into long tube, which is coiled to save space and put in an oven. An unreactive carrier gas, like nitrogen. 20. Refer to big sheets

Use of Mg(OH)2

To treat constipation and neutralise excess stomach acid safe as it is weakly alkaline

The scientist used percentage cover rather than frequency to record the abundance of algae present. Suggest why. (1)

Too many to count

The diet of a person can increase the risk of coronary heart disease. Explain how. (5)

Too much saturated fat; increases cholesterol in blood; which can lead to the development of fatty deposits in artery walls; These can cause thrombosis; and reduce the diameter of coronary arteries; so less oxygen is supplied to the heart muscle

What does the area under a Maxwell-Boltzmann distribution curve represent?

Total number of molecules

Infection by the cholera bacterium can cause acute diarrhoea. Explain how. (2)

Toxin produced by bacterium causes chloride ions to move into lumen of intestine; Water potential of intestine falls so water moves by osmosis into intestine

Give one limitation of using a line transect to collect data. (1)

Transect line may not go through representative areas

Describe what should be done after Stage 3 to obtain a sample containing only mitochondria. (2)

Transfer supernatant to another tube; Spin at a higher speed

Outline how a muscle contracts. (6)

Tropomyosin molecule prevents myosin head from attaching to the binding site on the actin molecule; Calcium ions released from the endoplasmic reticulum cause the tropomyosin molecule to pull away away from the binding sites on the actin molecule; Myosin head now attaches to the binding site on the actin molecule; Head of myosin changes angle, moving the actin filament along. ADP molecule is released; ATP molecule fixes to the myosin head, causing it to detach from binding site; Hydrolysis of ATP to ADP by ATPase provides the energy for the myosin head to resume its normal position. This process is repeated further along the actin filaments

(Refer to Jan 2011) The Rhesus blood group is genetically controlled. The gene for the Rhesus blood group has two alleles. The allele for Rhesus positive, R, is dominant to that for Rhesus negative, r. The diagram shows the inheritance of the Rhesus blood group in one family. Explain one piece of evidence from the diagram which shows that the allele for Rhesus positive is dominant. (2)

Two Rhesus positives produce Rhesus negative children; if Rhesus positive was recessive, all children of 3 and 4 would be Rhesus recessive

The rats used in the investigation had type I diabetes. This form of gene therapy may be less effective in treating rats that have type II diabetes. Explain why. (1)

Type 2 diabetes still produces insulin

Describe the two main types of diabetes. (4)

Type I (insulin dependent); unable to produce insulin, begins in childhood, body's immune system attacks its own cells - B cells of islets of Langerhans; Type II (insulin independent); glycoprotein receptors on body cells lose responsiveness to insulin, develops in older people, obesity and bad diet likely to result in this type

Scientists have developed a standard procedure for comparing RFI in cattle. They control two factors. These are type of food and environmental temperature. Explain why each of these factors needs to be controlled. (4)

Type of food: May vary in protein; May affect digestibility; Temperature Will affect heat loss; Need to maintain body temperature

Ozone and CFCs

UV radiation breaks C-Cl bons in CFCs, so Cl free radicals are in the upper atmosphere and catalyse ozone decomposition into O2 molecules

(Refer to June 2013 paper) Algae are photosynthesising organisms. Some algae grow on rocky shores. A scientist investigated succession involving different species of algae. He placed concrete blocks on a rocky shore. At regular intervals over 2 years, he recorded the percentage cover of algal species on the blocks. His results are shown in the graph. Name the pioneer species. (1)

Ulva lactuca

Reeds have hollow, air-filled tissue in their stems which supplies oxygen to their roots. Explain how this enables the roots to take up nitrogen-containing substances. (2)

Uptake by roots involves active transport; Requires ATP

(Refer to Jan 2013 paper) Students investigated the effect of removing leaves from a plant shoot on the rate of water uptake. Each student set up a potometer with a shoot that had eight leaves. All the shoots came from the same plant. The potometer they used is shown in the diagram. Describe how the students would have returned the air bubble to the start of the capillary tube in this investigation. (1)

Use tap to add water from resevoir

Give three possible uses of stem cells which have been grown in vitro and then induced to develop into a wide range of different human tissues. (3)

Used to regrow tissues that have been damaged such as: heart muscle cells which have been damaged due to heart attack; skin cells which have been damaged by burns or wounds; can be used to produce B cells of the islets of Langerhans in people with Type I diabetes

Ways of minimising heat loss in a calorimeter

Using a draught screen, mineral wool, lid, enclosing the flame, burning in pure oxygen not air. and using a bomb calorimeter, which is the most accurate piece of apparatus, so it is used to find data book values

When malathion is used as a pesticide, it is often sprayed onto aquatic habitats at concentrations of 0.1 to 1.6 mg dm-3. The scientists tested the effect of malathion at concentrations of 0.001 to 10 mg dm-3. Suggest why. (2)

Using less pesticide is more cost effective; May be more concentrated due to evaporation

What conditions (in terms of solvent) are needed for the conversion of a halogenoalkane to a nitrile?

You need aqueous and ethanolic KCN - the alcohol is a universal solvent which makes everything mix.

What are Van der Waals forces?

Van der Waals forces cause all atoms and molecules to be attracted to one another. They're caused by temporary dipoles which occur when the moving electrons within a charge cloud are more to one side than the other. Larger molecules or molecules with a greater surface area have more Van der Waals forces.

Explain how the use of pesticides can result in resistant strains of insect pests. (5)

Variation in pest population; Due to mutation; Allele for resistance; Pests with resistance survive and breed; Increase in frequency of allele

Changes in ecosystems can lead to speciation. A high concentration of copper in soil is toxic to most plants. In some areas where the soil is polluted with copper, populations of grasses are found to be growing. These populations of grass belong to a species also found growing on unpolluted soils. It has been suggested that a new species of grass may evolve on soil that has been polluted with copper. Explain how this new species might evolve. (5)

Variation; Mutation; Some plants have allele to survive in high concentration of copper; Selected organisms survive and reproduce; Increase in frequency of allele

How is body temperature conserved in endotherms? (4)

Vasoconstriction - diameter of arterioles near skin surface decrease, less blood through capillaries, less heat loss; Shivering produces metabolic heat; Raising of hair, traps thick layer of still air, acting as an insulator; Increased metabolic rate - more hormones that increase metabolic rate and respiration produced

Explain why the skin of humans often appears paler on a cold day than on a hot day. What is the significance of this difference? (3)

Vasoconstriction - smaller diameter of arterioles in the skin; Reducing blood flow to skin surface so appears pale; Significance: conserves body heat to maintain constant body temperature

How is body temperature lost in endotherms? (4)

Vasodilation - diameter of arterioles near skin surface increase, more blood through capillaries, more heat loss; Increased sweating - water evaporates from skin surface, carrying heat energy from the body with it; Lowering of hair - reduces layer of still air next to the body which acts as insulator, allowing more heat to be lost; Behavioural mechanisms such as seeking out shade

The maximum pressure in the ventricle is much higher than that in the atrium. Explain what causes this. (2)

Ventricle has thick muscular wall; So contractions are stronger

What axes does a chromatogram have? What causes the first peak on the chromatogram for gas chromatography?

Vertical axis: relative intensity Horizontal axis: time The solvent

How can original monomers be produced from condensation polymers? Display this reaction, starting from the repeating unit of a polyamide.

Via hydrolysis 4. Refer to big sheets

Group 2 Metals + Water

Vigour increases down group 2 hydroxides are produced X + 2H2O (l) → X(OH)2(aq) + H2(g) fizzing and effervescence increases down the group solution heats up more down the group (move exothermic) metal dissolves faster down the group so the amount of white precipitate reduces down the group

Pathogens affect humans. They also affect farm animals. Once pathogens have entered the body of an animal they can cause disease. Vets sometimes have difficulty identifying the disease from which a particular animal is suffering. Until recently, they have had to take blood samples and send them to a laboratory. The laboratory carries out tests on the sample. Other than bacteria, name one type of pathogen. (1)

Virus

Identify two events that may lead to colonosation of an inhospitable environment. (2)

Volcanoes erupting and depositing lava; Lakes or ponds being created by land subsidising

Larger organisms have specialised gas exchange systems. Explain how the countercurrent mechanism helps fish to extract oxygen from water. (3)

Water and blood flow in opposite directions; Oxygen difference maintained; so diffusion always occurs

Explain the change in mass of untreated leaves in set A shown in the graph. (3)

Water evaporates out of leaf; Via a water potential gradient; The water is then not being replaced

Use your knowledge of the cohesion-tension theory to explain how water in the xylem in the roots moves up the stem. (4)

Water evaporates out the leaves; which creates a water potential gradient; Water is drawn out of xylem; which creates tension and a pulling effect

The photolysis of water is an important part of the process of photosynthesis. Describe what happens in the photolysis of water. (2)

Water forms hydrogen ions and electrons; oxygen is formed

The student assumed that water uptake was equivalent to the rate of transpiration. Give two reasons why this might not be a valid assumption. (2)

Water is used to provide support; Water is used in photosynthesis

Kwashiorkor is a disease caused by a lack of protein in the blood. This leads to a swollen abdomen due to a build up of tissue fluid. Explain why a lack of protein in the blood causes a build up of tissue fluid. (3)

Water potential in capillary is higher; So less water is removed; by osmosis into capillary

In children, some diets may result in a low concentration of protein in fluid F. This can cause the accumulation of tissue fluid. Explain the link between a low concentration of protein in fluid F and the accumulation of tissue fluid. (3)

Water potential in capillary is higher; so less water absorbed into the blood capillary; by osmosis

What is wavenumber? What is the fingerprint region and what is special about it?

Wavenumber/cm^-1 = 1 divided by wavelength/cm, where wavelength is of the infrared radiation. Fingerprint region is the region in an infrared spectrum between 500cm^-1 and 1500cm^-1, which is specific to a particular molecule.

Basic buffer

Weak base and a salt of a weak base

Describe and explain the symptoms of pulmonary fibrosis. (4)

Weakness and fatigue; due to less oxygen being taken into blood, resulting in less respiration; Shortness of breath; due to thickened epithelium of alveoli which increases diffusion pathway and slows the rate of diffusion

1. High melting points: strong electrostatic attraction between positive metal ions and delocalised electrons need lots of energy to overcome. 2. Good thermal conductors: delocalised electrons and positive metal ions can vibrate and pass kinetic energy to each other. 3. Good electrical conductors: they contain delocalised electrons, which are free to move through the metal carrying charge. 4. Insoluble (except in liquid metals): many strong metallic bonds need lots of energy to break

What are 4 properties of metals? Why?

1. High melting point due to many strong covalent bonds between constituent carbon atoms, which take lots of energy to break 2. It's extremely hard 3. Vibrations travel easily through the stiff lattice, making it a good thermal conductor 4. It doesn't contain delocalised electrons, so doesn't conduct electricity 5. It doesn't dissolve in any solvent due to the many strong covalent bonds in it 6. Its structure makes it refract light, so it sparkles a lot

What are 6 properties of diamond? Why?

Molecules with the same molecular formula but their atoms arranged differently

What are isomers?

Positive metal ions surrounded by a sea of delocalised electrons

What are metallic structures like?

Molecules with the same structural formula but a different arrangement of their atoms/ groups in space

What are stereoisomers?

A shared pair of electrons between two atoms, both of which come from the same atom

What is a coordinate bond?

Complete: carbon dioxide and water Incomplete: carbon monoxide and soot (carbon particulates)

What is always formed in complete combustion of an alkane? What side products can you get in incomplete combustion?

The simplest whole number ratio of atoms of each element in a compounds

What is an empirical formula?

The power of an atom to attract the electron density in a covalent bond towards itself

What is electronegativity?

The simplest whole number ratio of atoms of each element in a compounds

What is empirical formula?

An algebraic formula that can describe any member of a family of compounds

What is general formula?

Actual number of atoms of each element in a compound

What is molecular formula?

(Mr of desired product/Sum of Mr's of all reactants) x 100%

What is percentage atom economy?

(Actual yield/ Theoretical yield) x 100%

What is percentage yield?

Shows bonds of the carbon skeleton only, with any functional groups drawn. Regular C and H atoms not shown

What is skeletal formula?

Shows the atoms carbon by carbon, with the attached hydrogen atoms and functional groups

What is structural formula?

2CO + 2NO → 2CO2 + N2 Metals: platinum and rhodium

What reaction occurs in a catalytic converter? What are 2 metals are used in a catalytic converter?

What was found in Rutherford's gold foil experiment?

When alpha particles were fired at a thin gold sheet, most of them passed straight through with a very small number deflected straight back.

When does the nitration of benzene occur? What does one of the chemical act as, and how? Write the equation and display the mechanism for the nitration of benzene. What happens to the H+ ion produced? What must be done for only one NO2 group to add to the benzene ring - what is this reaction called?

When benzene is warmed with concentrated concentrated nitric and sulfuric acids, you get nitrobenzene. -Sulfuric acid acts as a catalyst - it helps to make the nitronium ion, NO2^+, which is the electrophile. -Refer to big sheets -It reacts with the HSO4^- ion to make H2SO4 -For mononitration, you must keep the temperature below 55°C

Explain how stimulation of pressure receptors during exercise results in a change in heart rate. (6)

When blood pressure is higher than normal, they send an impulse to the medulla; Fewer impulses from medulla along parasympathetic nerve; To SAN, decreasing heart rate; When blood pressure is lower than normal, they send an impulse to the medulla; More impulses from medulla along sympathetic nerve; To SAN, increasing heart rate

Catalyst poisoning

When impurities in a reaction mixture bind to a catalyst's surface, blocking reactants from being adsorbed and reducing the effectiveness of the catalyst.

When does air enter the lungs? (1)

When the air pressure of the atmosphere is greater than the air pressure inside the lungs

There are many strong electrostatic forces of attraction (ionic bonds) between cations and anions in the lattice that need lots of energy to break

Why do ionic compounds have high melting points?

Only then are their ions free to move and carry charge

Why do ionic compounds only conduct electricity when dissolved or molten?

1. Carbon atoms in the C=C bond and the next atoms bonded to them are planar. 2. Atoms can't rotate around the C=C bond - they're fairly rigid, so don't bend much either. 3. Restricted rotation of groups/ atoms around the C=C bond causesE/Z isomerism

Why does E/Z isomerism exists for C=C double bonds?

Electron is now taken from a higher energy subshell (3p) in Al with extra electron shielding (due to 3s subshell, from which electron is removed in Mg) so is less strongly attracted to the nucleus, despite increased nuclear charge

Why does first IE decrease between Mg and Al?

Number of shells increases and extra inner shells shield outer electrons from nuclear attraction even more, and outer electrons get further from the nucleus, so lose attraction to it. Effects of increasing nuclear charge overridden

Why does first IE decrease down Group 2?

Number of protons in nucleus and positive nuclear charge increases and electron shielding remains similar, so outer electrons get more strongly attracted to the nucleus

Why does first IE generally increase across a period?

Number of delocalised electrons per atom stays the same and delocalised electrons become further from positive metal ion nuclei, due to extra shells, so less strongly attracted to them. This outweighs increased number of protons in the nucleus and increased nuclear charge.

Why does melting point of a metal decrease down a group?

Number of protons in the nucleus and positive nuclear charge increase and number of delocalised electrons per atom increases, while electron shielding stays roughly the same, so more metallic bonds form and they need more energy to break in total.

Why does melting point of a metal increase across a period?

Halogen atoms are much more electronegative than hydrogen atoms, so more strongly attract the electron density in the covalent bond.

Why is a carbon-halogen covalent bond polar?

There's a small electronegativity difference between carbon and hydrogen

Why is the carbon-hydrogen bond covalent?

In humans, both sympathetic and parasympathetic divisions of the autonomic nervous system influence the secretion of saliva. When food is in the mouth, increased parasympathetic stimulation of the salivary glands results in increased secretion of saliva. Explain the benefit of increased sympathetic stimulation of the salivary glands once the food has been swallowed. (2)

Will reduce secretion of saliva; And prevent unnecessary expenditure of energy

SCID is a severe inherited disease. People who are affected have no immunity. Doctors carried out a trial using gene therapy to treat children with SCID. The doctors who carried out the trial obtained stem cells from each child's umbilical cord. Give two characteristic features of stem cells. (2)

Will replace themselves; Can develop into other cells

CClF3 → .CCl2F + Cl. UV light needed Cl. + O3 → O2 + ClO. ClO. + O3 → 2O2 + Cl. 2O3 → 3O2 Cl. is catalyst

Write the reactions for the decomposition of ozone in the upper atmosphere by trichlorofluoromethane, listing any conditions. Write an overall reaction at the end. What does the Cl. free radical act as?

O2 → 2O. UV light is required O2 + O. → O3

Write the reactions for the formation of ozone in the upper atmosphere, listing any conditions.

Describe how you could determine whether two Ranunculus plants belong to the same species. (2)

You could breed them together; Same species indicated by fertile offspring

Formula of Cu2+ metal aqua ion in solution

[Cu(H2O)6]2+

Substance made when [Cu(H20)6]2+ reacts with conc. HCl

[CuCl4]2- Green Soln

Substance made when [Fe(H2O)6]2+ reacts with ammonia in excess

[Fe(H20)3(OH)3] brown ppt due to oxidation

Substance made when [Fe(H2O)6]2+ reacts with dil ammonia

[Fe(H20)4(OH)2] Green Ppt

Substance made when [Fe(H2O)6]2+ reacts with dil sodium hydroxide

[Fe(H20)4(OH)2] Green Ppt

Explain why the expression for Kw does not include the concentration of water

[H2O] is very high (compared with [H+] and [OH-]), so [H2O] is effectively constant.

Simplification of Ka if a weak acid only is present

[H^+]^2 / [HA]

Explain how retinal convergence enables a person to see in dimly lit conditions. (2)

action potentials or generator potentials from several receptors sent to single synapse; sufficient neurotransmitter released; action potential more likely to be generated in this neurone

(Refer to exam q) Use the information in Figures 3 and 4 to suggest how glycogen breakdown in liver and muscle cells is increased when an animal runs away from a predator. (6)

adrenaline binds to receptors on muscle cell; causing increased glycogen phosphorylase activity; more glucose phosphate for respiration; calcium ions enter muscle cells and glycogen broken down; lower blood glucose as glucose used by muscles; glucagon released and binds to receptors

Female great tits usually lay between 3 and 14 eggs in a nest. In the same year, the birds do not all lay the same number of eggs. Explain how one factor, other than the number of breeding pairs, could influence the number of eggs laid by a great tit. (1)

age of bird - young or old birds produce fewer eggs

Each student repeated an experiment and the results were pooled. Explain the advantages of collecting a large number of results. (2)

allows anomalies to be identified; allows use of statistical test

Suggest how the amino acids at positions 35 and 52 are held close together to form the active site. (2)

amino acid chain folds; hydrogen bonds hold tertiary structure together

Horses may be kept in stables in winter. Horse manure is a mixture of straw, urine and faeces that accumulates in the stables. It is a useful nitrogen-rich fertiliser. Explain how the nitrogen-containing compounds absorbed from the horses' food become nitrogen-containing compounds in the urine produced. (4)

amino acids in food; deaminated; to form urea; excreted by kidney

The vegetation on a large heap of waste from an old mine was investigated. The table shows the results of the measurements of certain factors in 1m2 frame quadrats placed on the south-facing slope. Quadrat Angle of Vegetation Moisture pH of slope / ° cover / % of soil /% soil 1 45 60 17.2 5.6 2 30 70 14.6 4.2 3 25 68 20.3 5.2 4 12 100 23.5 7.1 5 7 85 21.0 5.4 6 1 100 21.2 6.8 Which of the factors measured are abiotic? (1)

angle, moisture and pH

When no fertiliser was added, the mass of crop from field A was higher than from field B. Explain this difference. (2)

because cattle excreted; in field B crop used nutrients last year

Explain the process of aerobic respiration. (8)

by glycolysis, glucose is broken down into pyruvate in the cytoplasm; pyruvate converted to acetyl CoA; by oxidative decarboxylation; acetyl CoA enters the Krebs cycle; Krebs cycle yields a small amount of ATP; and FADH2 and NADH; these molecules pass electrons to electron transport chain; oxygen is final electron acceptor;

(Refer to exam q) The diagram shows the stages in one cycle that results in movement of an actin filament in a muscle sarcomere. Describe how stimulation of a muscle by a nerve impulse starts the cycle shown in the diagram. (3)

calcium ions interact with the tropomyosin molecule; to reveal binding sites on actin; allowing myosin heads to bind to exposed sites on actin filament

Advantages of Electrolysis

can be used for metals more reactive than carbon

Spotted knapweed is a common weed in the USA. Two methods, chemical control and biological control, have been used to reduce the numbers of spotted knapweed plants. The table shows the results of an investigation comparing the effectiveness of these two methods. Describe the pattern of plant numbers resulting from the use of (i) chemical control (ii) biological control (2)

chemical: numbers fluctuate throughout year; biological: numbers fairly constant throughout year

Explain what is meant by monoculture. (1)

cultivation of single species

Why are polyalkenes unreactive?

due to strong C-C and C-H bonds

Conditions for Nucleophillic Substitution to produce amines

excess conc. NH3 in ethanol under pressure

Callus tissue develops into either shoots or roots depending on the relative concentration of the plant growth regulators used. Use your knowledge of genes to suggest how these plant growth regulators determine the type of plant tissue formed. (1)

express different genes

Advantages of using Ethene to produce ethanol

faster, purer, continuous (cheaper)

Give two advantages of producing plants using this method rather than from seeds. (2)

favourable characteristic can be maintained in all plants; higher success rate

The rate at which a heather plant produced new biomass was measured in g per kg of heather plant per year. This rate decreased as the plant aged. Use the information in the table to explain why. (3)

fewer leaves; less photosynthesis to produce new biomass; competition with other species for nitrates

Monoculture often involves the use of large amounts of pesticides. Some of these pesticides are toxic to species that are not pests. These animals may be killed immediately when the pesticide is applied. Explain one other way by which the use of pesticides can lead to the death of animals that are not pests (2)

food source killed by pesticide; insufficient food for survival

Cross-channel swimmers experience a large decrease in external temperature when they enter the water. Describe the processes involved in thermoregulation in response to this large decrease in external temperature. (7)

hypothalamus (containing the thermoregulatory centre); has receptors which detect temperature changes of blood; receives impulses from receptors in skin; nerve impulses transmitted from hypothalamus; results in vasoconstriction; less blood to skin; shivering generates heat via respiration

Measuring the rate of reaction of magnesium

if not cleaned properly both Mg and MgO will react with acid at different rates. Mg + 2HCL →MgCL2 + H2 MgO + 2HCL → MgCl2 + H2O

Describe the sequence of events which allows information to pass from one neurone to the next neurone across a cholinergic synapse. (8)

impulse causes calcium ions to enter axon; causes vesicles to fuse with presynaptic membrane; acetylcholine released; acetylcholine diffuses across synaptic cleft; and binds with receptors on sodium ion channels on postsynaptic membrane; sodium ions diffuse into postsynaptic neurone; acetylcholinesterase hydrolyses acetylcholine to prevent further action potentials; ATP from mitochondria used to recombine choline and ethanoic acid into acetylcholine

(Refer to exam q) As well as pulling the finger away, the gardener also feels pain caused by the thorn. Explain how she becomes aware of the pain.(3)

impulses to brain; sensory areas (in brain); processing by association area

Explain what causes the conduction of impulses along a non-myelinated axon to be slower than along a myelinated axon. (3)

in a myelinated axon there is ion movement only at the nodes; and the impulse jumps from node to node; whereas in non-myelinated axons the impulse has to travel along the whole membrane

The graph shows the number of species of insects reported to be resistant to at least one insecticide between 1920 and 1980. (slow increase then sharp increase at 1950). Suggest one reason why there was a rapid rise in resistant species after 1950. (1)

increased use of insecticides

Epilepsy may result when there is increased neuronal activity in the brain. One form of epilepsy is due to insufficient GABA. GABA is broken down on the postsynaptic membrane by the enzyme GABA transaminase. Vigabatrin is a new drug being used to treat this form of epilepsy. The drug has a similar molecular structure to GABA. Suggest how Vigabatrin may be effective in treating this form of epilepsy. (2)

inhibits enzyme which breaks down GABA; more GABA available to inhibit neurone

Explain how digestion of insects helps the sundew to obtain additional nitrogen compounds. (2)

insects contain proteins; which are digested into amino acids

The binding of GABA to receptors on postsynaptic membranes causes negatively charged chloride ions to enter postsynaptic neurones. Explain how this will inhibit transmission of nerve impulses by postsynaptic neurones. (3)

inside becomes more negatively charged; stimulation does not reach threshold level; depolarisation does not occur

Differences in cyanide production may affect the total number of clover plants growing in different areas. Describe how you would use quadrats in an investigation to determine whether or not there is a difference in the number of clover plants in two large areas of equal size. (4)

large and equal number of quadrats in each area; random sampling method, such as numbers out of a hat; percentage cover per quadrat; mean value for each area

A person swimming in cold water may not be able to maintain their core body temperature and begins to suffer from hypothermia. Explain why a tall, thin swimmer is more likely to suffer from hypothermia than a short, stout swimmer of the same body mass. (2)

larger surface area to volume ratio; less insulation

A large lake is surrounded by fields. These fields are separated from each other by hedges. One hundred years ago the lake was a habitat for many plants, invertebrates and fish. Today the lake has no fish and few plants or invertebrates. Explain how increased use of inorganic fertilisers on the fields may have led to these changes. (5)

leaching of nitrates; leads to increased growth of algae; death of plants; respiration of microorganisms uses up oxygen; fish die due to lack of oxygen

BaSO4

least soluble barium meal given to patients to absorb x rys reacts with sulphuric acid - slow reaction BaSO4 covers metal and prevents further reduction Ba + H2SO4 →BaSO4 Sulphate Test - unknown compound + BaCl2 + HCl - white precipitate of BaSO4 ( Ba2+ + SO4 2- →BaSO4(s) )

Two fields, A and B, were used to grow the same crop. The fields were divided into plots. Different masses of fertiliser containing sodium nitrate were applied to these plots. After six weeks, samples of crop plants from each plot were collected and their mass determined. The results are shown in the table. Describe the pattern shown by the data for field B. (1)

mass produced increases then levels off at 17.1 kg m-2

Robins defend their territories against other robins by fighting and other aggressive behaviour. They do not show aggressive behaviour towards similar-sized birds of other species. Suggest how other robins are more of a threat to a robin's breeding success than are similar-sized birds of other species. (3)

other robins have same niche; competition from other robins; for food

Give one piece of evidence which suggests that the conversion of pyruvate to ethanol involves reduction. (1)

oxygen is removed from pyruvate

pH of Cu2+ metal aqua ion in soln

pH 5/6

What is the equation for pH? What does pH range from?

pH = -log10[H+] pH ranges from 0 to 14

What is the importance of homeostasis? (6)

pH and temperature affect enzymes; may reduce efficiency of enzymes/denature enzymes; need reactions to occur at a constant, predictable rate; Changes to water potential causes water to enter or leave cells; so cells shrink and expand; so blood glucose must be maintained

The difference between the samples was thought to be due to abiotic factors in the soil. Give two such factors and suggest how each could be measured. (2)

pH with indicator; temperature with an electronic thermometer

Other than soil moisture, give one abiotic factor and explain how it could lead to the abundance of Ranunculus repens in the furrows of this field. (2)

pH; Greater nutrient availability

What is pKa equal to? How do you calculate Ka from pKa?

pKa = -log10Ka Ka = 10^-pKa

What is the ideal gas equation?

pV=nRT p = pressure in pascals V = Volume in m3 n = number of moles R = 8.31 the gas constant T = temperature measured in kelvin

Some plants have adaptations that enable them to grow on lawns that are cut regularly. Suggest two of these adaptations and explain the advantage of each. (4)

plant grows close to ground; so not damaged during mowing; able to repair damaged leaves; quick recovery after action by mower

What is the equation involving specific heat capacity? What units does T have? When is q negative, when is it positive?

q = mcΔT T's units are Kelvin q is negative for an exothermic reaction but positive for an endothermic reaction

Equation for Measuring ∆H of a reaction

q = mc∆T ∆H = q/mol m = g or cm3 c = Jg-K-, is the specific heat capacity, the amount of heat needed to raise the temperature of 1g of a substance by 1 K q= J

In a human population, one in every 1000 children born had Tay-Sachs disease. Use the Hardy-Weinberg equation to calculate the percentage of this population you would expect to be heterozygous for this gene. Show your working. (3)

q2/p2/tt = 0.001 or 1 divided by 1000; p/q/T = 0.968 - 0.97; Understanding that heterozygous = 2pq; = 5.8 - 6.2%

The iris of the eye contains antagonistic muscles which control the diameter of the pupil. Use your knowledge of the iris muscles to explain what is meant by antagonistic muscle action. (3)

radial and circular muscles in iris; opposing action = antagonistic; radial contraction increases pupil diameter / circular contraction reduces (or vice versa for iris).

Normally, for the reaction CH3COCH3 + I2 → CH3COCH2I + HI The following rate equation was deduced: rate = k [CH3COCH3][H+] A series of experiments was carried out using concentrations of propanone approximately 100 times the concentrations of iodine and hydrochloric acid. Suggest the rate equation under these conditions. Explain your answer.

rate = k [H+]. There's a large excess of propanone so [CH3COCH3] is effectively constant.

The population of England and Wales in 1851 was 18 million. Calculate the size of the population in 1852. Show your working. (2)

rate of increase = 34.3 - 22.0 = 12.3 per thousand, so increase = 18,000,000/1000 × 12.3 = 221 400; size of population = 18 000 000 + 221 400 = 18 221 400

Describe how this pyruvate is converted into a substance that enters the Krebs cycle. (2)

reacts with coenzyme A to give acetylcoenzyme A; NAD is reduced

A different form of epilepsy has been linked to an abnormality in GABA receptors. Suggest and explain how an abnormality in GABA receptors may result in epilepsy. (3)

receptors have different tertiary structure; GABA cannot bind; inhibition of neuronal activity does not occur

A suspension of chloroplasts was isolated from an aquatic plant and a reagent was added. The reagent is blue when oxidised and is colourless when reduced. The suspension of chloroplasts in blue reagent was exposed to sunlight. The blue colour disappeared. Use your knowledge of the light-dependent reactions of photosynthesis to explain why. (2)

reduced NADP formed; reduced NADP changes the dye colour

Many hedges have been removed from arable land in recent years. Explain two advantages to farmers of removing hedges. (2)

reduced competition for light, therefore increase in crop growth; more room so ease of ploughing

(Refer to exam q) Attempts are being made to conserve the natterjack toad, which breeds in ponds. A number of recommendations have been made about how to do this. Some of these are shown in the table, together with a reason for each one. Explain two ways in which these recommendations could reduce populations of animals other than common toads. (2)

reduction in insect predators from ponds, because ponds kept shallow; reduction in animals that prefer pH outside 5-7, because lime added

Reduced NADP produced during the light-dependent reactions of photosynthesis is used in the light-independent reactions. Explain how. (2)

reduction; of GP to triose phosphate

Calculating relative atomic mass

relative atomic mass = isotopic masses x percentages/total percentage

Explain the change in the mass of crop produced from field B when the mass of fertiliser added increases from 0 to 20kgha-1. (2)

replaces nutrients removed; fertiliser provides nitrate needed for protein production

Malaria is a disease caused by a parasite. Scientists investigated the effect of malaria on competition between two species of Anolis lizard on a small Caribbean island. They sampled both populations by collecting lizards from a large number of sites on the island. Explain the importance of collecting lizards from a large number of sites. (1)

representative

Explain why it takes time for the rod cells to recover their sensitivity to light after moving into darkness. (2)

rhodopsin broken down by light; time for resynthesis;

How many orbitals do each-sub shell contain?

s - 1 p - 3 d - 5 f - 7

Stereoisomer

same structural formula, atoms arranged differently in space

How is diffusion calculated? (1)

surface area x difference in concentration ------------------------------------------------------ length of diffusion pathway

Describe how the investigators could obtain the value for vegetation cover in each quadrat. (2)

system for subdividing quadrat into many squares; counting those where cover over 50%

The percentage of light absorbed by an aquatic plant was measured when it was exposed to different wavelengths. The rate of photosynthesis was also measured at each wavelength of light. The results are shown in the graph. (Refer to exam q in book) Describe and explain the relationship between light absorption and the rate of photosynthesis for the wavelengths of light between 410nm and 500nm. (2)

the more light absorbed, the greater the rate of photosynthesis; because light provides the energy for light dependent reactions

What are permanent dipole-dipole forces?

these are the weak electrostatic forces that occur between polar molecules.

Why aren't mean bond enthalpy values very accurate?

they are averaged over a range of compounds

Describe the role of calcium ions in the contraction of a sarcomere. (4)

they interact with the tropomyosin molecule; to reveal binding sites on actin; allowing myosin heads to bind to exposed sites on actin filament; energy released from ATP moves myosin head back to its original position

Explain how the reduced coenzyme produced in photosynthesis is used. (2)

used to reduce glycerate 3-phosphate; to glucose;

Explain the trichromatic theory of colour vision. (2)

three types of cones; each sensitive to different wavelength

whiy is HCl is used in the sulphate test

to remove carbonate ions impurities from sulphate ion salts as they would react with BaCl2 to give BaCO3 which is an incorrect result HCl + Na2CO3 →2NaCl + H2O + CO2 - fizzing - carbonate ions are removed

The molecular structure of cobra toxin is similar to the molecular structure of acetylcholine. Explain why the toxin permanently prevents muscle contraction. (2)

toxin competes for receptors; the toxin does not cause depolarisation

Using your knowledge of muscle contraction, explain the difference in the results between A and B. (2)

tropomyosin covers binding site on actin; no cross bridges formed so ATPase activity on myosin head reduced

Describe how you would use quadrats to determine whether a particular plant species has a clustered or a random distribution. (3)

use of random numbers to place quadrats; number of individuals counted in large number of quadrats; little variation random, large variation - clustered

When starfish feed on mussels they leave behind the empty shell. Explain how quadrats could be used to determine the percentage of mussels that had been eaten by starfish on a rocky shore (3)

use of random numbers; large number of quadrats; count number of dead and live mussels in unit area

Figure 2 shows the results of an experiment in which photosynthesising cells were kept in the light and then in darkness. In the experiment the cells were supplied with radioactively labelled 14CO2. Explain why the carbon dioxide used was radioactively labelled. (1)

used in photosynthesis allows detection of products

Explain what caused the amount of radioactively labelled glucose to decrease after the light was switched off. (1)

used in respiration

The mesquite tree grows in dry areas which have soils with low concentrations of ions. Its roots grow down to 25 metres and contain nitrogen-fixing bacteria. It is considered a pest in areas where farm animals graze because it out-competes grass. In some areas, young mesquite trees are cut down and then ploughed into the ground. This is expensive but makes the soil slightly more fertile for a few years. Using the information given, explain one way in which mesquite trees are adapted for survival. (1)

very long roots to reach water deep in the soil