CIE Biology AS Level

examples of xerophytes

"hinge cells" shrinkage causes lees to roll up; spins lessen surface area; needles lessen surface area; trichomes act as a physical barrier to water loss; swollen, succulent stems which store water.

carboxylic group

-COOH.

amine group

-NH2.

carbon dioxide transport

1. As hydrocarbonate ions in the plasma 2. As carbamino-haemoglobin in red blood cells 3. As CO2 in solution in plasma

Km (Michaelis-Menten constant)

1/2Vmax; a constant measure of an enzyme's affinity; the higher the affinity, the lower the Km value and the quicker the reaction will proceed to Vmax.

mm

10^-3

µm

10^-6

nm

10^-9

triose

3 carbon atoms C3H603

pentose

5 carbon atoms C5H10O5; common examples would be ribose and deoxyribose.

hexose

6 carbon atoms C6H12O6; common examples would be glucose, fructose, and galactose.

cholera-global distribution

Asia, Africa, Latin America.

the general formula of a carbohydrate

Cx(H2O)y

polynucleotides

DNA and RNA; referred to as nucleic acids.

DNA

Deoxyribonucleic acid; a molecule which contains the instructions that control the activities of the cell.

how is water transported from root to stem and leaf in the xylem?

MASS FLOW: reduces hydrostatic pressure→ hydrostatic pressure at top of the xylem becomes lower than the pressure at the bottom → pressure difference causes water to move up xylem vessels in continuous columns.

each chromatid contains _____ DNA molecule

ONE

the three phases of interphase

S phase, G1 phase, and G2 phase.

AIDS-site of action

T helper lymphocytes, macrophages, brain cells.

how is water transported from leaf to atmosphere?

TRANSPIRATION- water moves out of the stomata into the surrounding air because it follows he water potential gradient.

glycosidic bond

a C-O-C link between two monosaccharide molecules, formed by a condensation reaction.

nucleosome

a bead-like structure made o eight histone molecules, around which DNA is wrapped; nucleosomes are the fundamental subunits of chromatin.

callose

a carbohydrate that seals sieve plates when cut open; process called 'clotting'

hybridoma

a cell formed by the fusion of a plasma cell and a cancer cell; it can both secrete antibodies and divide by mitosis.

stem cells

a cell that can divide an unlimited number of times; when it divides, each new cell has the potential to remain a stem cell or to develop into a specialized cell such as a blood cell or a muscle cell.

mutation

a change in any gene.

condensation reaction

a chemical reaction involving the joining together of two molecules by removal of a water molecule.

lumen

a completely empty space inside a dead cell.

epidermis

a continuous layer on the outside of the plant, one cell thick, that provides protection; in stems and leaves it is covered with a waxy cuticle.

concentration gradient

a difference in concentrations; moving down would be going from high to low; moving up would be going from low to high.

antibiotic

a drug that kills or stops the growth of bacteria, without harming the cells of the infected organism.

transfer RNA (tRNA)

a folded, single-stranded RNA molecule hat carries an amino acid to a ribosome for protein synthesis.

polymer

a giant molecule made from many similar repeating subunits joined together in a chain; the subunits are much smaller and simpler molecules known as monomers; examples of biological polymers are polysaccharides, protein, and nucleic acids.

chlorophyll

a green pigment responsible for light capture in photosynthesis in algae and plants

immunoglobins

a group of plasma proteins formed from antibodies.

vascular bundles

a grouping of the xylem and phloem; outsides have caps made of schlerenchyma which provide support.

macrophages

a kind of phagocyte; larger than neutrophils; found in lungs, liver, spleen, kidney and lymph nodes; long-lived.

neutrophils

a kind of phagocyte; travel throughout the body paroling the tissues; short-lived.

macromolecule

a large biological molecule such as a protein, polysaccharide, or nucleic acid.

pericycle

a layer of cells, one to several cells thick, just inside the endodermis and next to the vascular tissue; new roots can grow from this layer; in stems it is formed form schlerenchyma.

phospholipids

a lipid molecule with the unusual property of having one end which is soluble in water; one of the three fatty acid molecules are replaced with a phosphate group, which is polar and can dissolve in water; the head of the molecule is now hydrophilic and the tails are still hydrophobic; this allows the molecule to form a membrane around a cell.

chromatin

a loosely coiled form of chromosome during interphase o the cell cycle; chromatin is made of DNA and proteins and is visible as loosely distributed patches or fibres within the nucleus when stained.

pH

a measure of the concentration of hydrogen ions in a solution; the lower the pH, the higher hydrogen ion concentration.

tonoplast

a membrane surrounding the plant vacuole which controls exchange between the vacuole and the cytoplasm.

starch

a mixture of amylose and amylopectin; commonly found in chloroplasts and in storage organs; starch is never found in animals.

tar

a mixture of compounds that settles on the lining of the airways in the lungs and stimulates a series of changes that may lead to obstructive lung diseases and lung cancer.

collenchyma

a modified version of parenchyma with extra cellulose deposited in the corners of the cells.

monosaccharide

a molecule consisting of a single sugar unit with the general formula

biological catalysts

a molecule that speeds up a chemical reaction but remains unchanged at the end of the reaction.

chloroplast

a photosynthetic organelle in eukaryotes; manufactures ATP from ADP.

polysaccharide

a polymer whose subunits are monosaccharides joined together by glycosidic bonds.; most important polysaccharides are starch, glycogen, an cellulose.

plasmodesmata

a pore-like structure found in plant cell walls; plasmodesmata of neighboring plant cells line up to form tube-like pores through the cell walls, allowing controlled passage of materials from one cell to the other; the pores contain ER and are lined with the cell surface membrane.

kinetochores

a protein structure found at the centromere of a chromatid tow which microtubules attach during ell division.

co-transporter

a protein which acts as a carrier for both sucrose and hydrogen ions at the same time.

globular protein

a protein whose molecules curl up into a "ball" shape; examples would be haemoglobin or myoglobin or enzymes; many have roles in metabolic reactions.

receptor molecules

a protein-molecule that receives chemical-signals from outside the cell.

hydrolysis reaction

a reaction in which a complex molecule is broken down to simpler ones; involving the addition of water.

active site

a region, usually a cleft or depression, to which another molecule or molecules can bind.

nucleus

a relatively large organelle found in eukaryotic cells, but absent from prokaryotic cells; the nucleus contains the cell's DNA and therefore controls the activities of the cells.

monomer

a relatively simple molecule which is used as a basic building block or the synthesis of a polymer; many monomers are joined together to make the polymer, usually by condensation reactions; common examples of molecules used as monomers are monosacchrides, amino acids, and nucleotides.

hydrogen bond

a relatively weak bond formed by the attraction between a group with a small positive charge on a hydrogen atoms and another group carrying a small negative charge.

fatty acids

a series of acids; they contain the acidic group-COOH; the larger molecules in the series have long hydrocarbon tails attached to the acid head of the molecule.

covalent bond

a shared pair of electrons which hods a molecule together.

substitution, the mutation

a single change in the amino acid sequence.

messenger RNA (mRNA)

a single-stranded RNA molecule that carries the genetic code from DNA to a ribosome.

nucleolus

a small structure, one or more of which is found inside the nucleus; the nucleolus is usually visible as a densely stained body; its function is to manufacture ribosomes using the information in its own DNA.

antitoxins

a special group of antibodies which block the toxins released by bacteria.

grana

a stack of circular thylakoids in a chloroplast.

chromosomes

a structure made of DNA and histones, found in the nucleus of a eukaryotic cell.

disaccharide

a sugar molecule consisting of two monosaccharides joined together by a glycosidic bond; most common are maltose(glucose+glucose), sucrose(glucose+fructose), and lactose(glucose+galactose).

antigens

a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies; each type of cell has its own type of antigen.

phagocytes

a type of cell that ingests and destroys pathogens or damaged body cells by the process of phagocytosis.

palisade mesophyll

a type of mesophyll that is column-shaped; they are near the surface of the upper surface of the leaf where they receive more sunlight and therefore contain more chloroplasts than spongy mesophyll.

spongy mesophyll

a type of mesophyll that is spongy in appearance because of the many large air spaces between the cells.

turnover rate

a typical enzyme can convert around one thousand substrate molecules into product per second.

cell surface membrane

a very thin membrane (about 7 nm diameter) surrounding all cells; it is partially permeable and controls the exchange of materials between the cell and its environment; seen as having three layers (trilaminar appearance).

cell wall

a wall surrounding prokaryote, plant and fungi cells; the wall contains a strengthening material which protect the cell from mechanical damage, supports it and prevents it from bursting by osmosis if the cell is surrounded by a solution with higher water potential.

the limit of resolution

about one half the wavelength of the radiation used.

plasma cells

activated B-cells that produce antibody molecules rapidly; they secret antibodies into the blood, lymph or onto the lining of the the lungs and the gut; do not live long.

testing for the presence of reducing sugars

add BENEDICT'S reagent to solution and heat it in water bath; if a reducing sugar is present the color of the solution will change.

testing for the presence of proteins

add BIURET reagent to solution; if a purple color emerges, protein is present.

testing for the presence of lipids

add ETHANOL and shake vigorously; if cloudy white suspension is formed, a lipid is present.

testing for the presence of starch

add IODINE to solution; if the solution turns blue-black starch is present.

structure of ATP

adenine attached to a sugar to make adenosine; adenosine attached to three phosphates to make ATP.

warming the air breathed in

air flows in → warmed to body temperature and moistened by evaporation from the lining; protecting the inside surfaces of the lungs from drying out.

tuberculosis-methods of transmission

airborne droplets, undercooked meat or unpasterized milk.

measles-method of transmission

airborne droplets; coughing or sneezing.

trachea

airway that leads from the throat to the lungs; branches into two bronchi; contains irregular C-shaped rings of cartilage.

lipids

all organic molecules not soluble in water; most familiar are fats and oils.

nuclear pores

allow and control exchange between the nucleus and the cytoplasm.

red blood cells

also called erythrocytes; red color caused by haemoglobin; first cells are formed in the liver then taken over by the bone marrow; do not live long.

nuclear division

also known as the M phase; growth of the cell stops during mitosis; after the nucleus divides into two, the whole cell divides to create two genetically identical cells.

smallpox

an acute, highly infectious disease caused by the variola virus and transmitted by direct contact; red spots, swollen eyelids.

partially permeable membrane

an effective barrier between the cell and its surrounding materials. It allows a controlled traffic of materials across it in both directions.

Vmax

an enzyme's maximum possible rate of reaction; V stands for velocity.

disease

an illness or disorder of the body or mind that leads o poor health; each one associated with set of signs and symptoms.

prosthetic group

an important, permanent, part of a protein molecule but is not made of amino acids; for example a haem group.

freely permeable membrane

an ineffective barrier that would not keep anything out. instead the chemicals of the cell would simply mix with the surrounding chemicals by diffusion and nothing would exist.

tumour

an irregular mass of cells.

vacuole

an organelle found in eukaryotic cells; a large, permanent central vacuole is a typical feature of plant cells, where t has a variety of functions, including storage of biochemicals such as salts, sugars and waste products; temporary vacuoles(also known as phagocytic vessels), may form in animal cells.

golgi body

an organelle found in eukaryotic cells; the golgi apparatus consists of a stack of flattened sacs, constantly forming at one end and breaking up into golgi vesicles at the other end; golgi vesicles carry their contents to other parts of the cell, often to surface membrane for secretion; the golgi apparatus chemically modifies the molecules it transports; collects, processes, and sorts molecules (particularly proteins from Rough ER).

vector

an organism which carries a disease from one person to another or from an animal to a human.

dipole

an unequal distribution of charge in a molecule.

malaria-treatment

anti-malaria drugs: quinine and chloroquine; prophylactic drugs.

carcinogen

any agent that causes cancer.

source

any area of the plant in which sucrose is loaded into the phloem; for example, photosynthesizing leaf or storage organ.

sink

any areas where sucrose is taken out of the phloem; for example, the roots.

the effect of substrate concentration

as substrate concentration increases, initial rate of reaction also increases; this is until Vmax i reached and the initial rate of reaction levels out.

the effect of temperature

as temperature increases the rate of reaction increases until the optimum temperature is reached and the enzyme will become denatured if the environment becomes too high.

end-product inhibition

as the enzyme converts substrate to product, it is slowed down because the end-product binds to another part of the enzyme and prevents more substrate binding; end product can lose its attachment to the enzyme and go on to be used elsewhere, allowing the enzyme to reform into its active state.

centrosome

assemble microtubules during nuclear division.

mycorrhizas

association of fungi which act as a mass of fine roots which absorb water and nutrients from the soil and transport them to the plant.

chronic obstructive pulmonary diseases (COPD)

asthma, chronic bronchitis, and emphysema

how the temperature affects diffusion

at higher temperatures, molecules and ions have much more kinetic energy than at low temperatures; they move around faster, and thus diffusion takes place faster.

ventricular diastole

atria and ventricles relax → semi-lunar valves in the aorta and pulmonary artery are pushed shut → blood flows from he veins through the atria and into the ventricles.

hydrophilic

attracted to water.

phagocytosis

attraction (chemotaxis) → recognition and attachment → endocytosis → bacteria within a phagocytic vacuole → fusion of lysosomes and phagocytic vacuole → killing and digestion.

adhesion

attraction to other things, specifically the cellulose and lignin in the walls of xylem vessels.

multiple resistance

bacteria have this when they live in areas here there is widespread use of antibiotics; bacteria may have plasmids carrying resistance genes for several antibiotics.

induced fit hypothesis

basically the same as lock and key hypothesis, just adds the idea that the enzyme, and sometimes the substrate, can change shape slightly to as the substrate molecule enters the enzyme, in order to ensure a perfect fit.

transmission electron microscope TEM

beam of electrons pass through specimen therefore viewing the inside of the cell.

cholera-prevention

better sewage; better draining; clean water supply.

atrial systole

both atria contract → blood flows from the atria into the ventricles; back flow is prevented by closure of valves in the veins.

ventricular systole

both ventricles contract → atrioventricular are pushed shut by the pressurized blood in the ventricles → semi-lunar valves in the aorta and pulmonary artery are pushed open. Blood flows from the ventricles into the arteries.

coronary arteries

branches from the aorta; deliver oxygenated blood to the walls of the heart itself.

bronchi

branches from trachea; and then branches further into bronchioles; contains cartilage.

lysosomes

breakdown of unwanted structures; in white blood cells, lysosomes are used to break down bacteria.

types of pentose sugars in DNA/RNA

can either be a ribose or a deoxyribose; ribose is in RNA; deoxyribose is in DNA.

the transport of mineral ions

can move apoplastic or symplastic; or through mass flow; also can enter through types of diffusion; one important control point is the root endodermis, where the Casparian strip forces ions to pass through living cells before they can entire the xylem.

benefits of a light microscope

can observe living cells; can observe in color; good cost.

benefits of an electron microsope

can obtain a resolution of 0.5 nm (400 x better than light microscope); this also means a higher magnification can be obtained; possible three-dimensional viewing depending on the EM.

carcinogens

cancer-causing compounds; cause mutations on the genes that control cell division.

disadvantages of an electron microscope

cannot observe living cells because of vacuum; cannot observe in color; very expensive.

disadvantages of a light microscope

cannot reach a great magnification; can only view in 2D.

lung cancer

carcinogens react directly or they breakdown cells → mass development of cells → tumour; common symptoms: coughing up blood, difficult breathing.

phloem

carries substances made by photosynthesis from the leaves to the other areas of the plant; can move in different directions in different parts of the phloem.

mucus

catches particles and dust that enters the airways.

vessel elements

cells that are involved with the transport of water; arranged end to end; lignin laid around cell and contents begin to die forming lumen.

anaphase

chromatids move to opposite poles; centromeres first, pulled by microtubules.

human gas exchange system adaptations

clean and warm the air that enters during breathing; maximize the surface area for diffusion of oxygen and carbon dioxide between the blood and atmosphere; minimize the distance for this diffusion; maintain adequate ingredients for this diffusion.

companion cells

close to each sieve element; the number of ribosomes and mitochondria is larger than normal; numerous plasmodesmata pass between these and sieve elements for direct contact through the cytoplasm.

carbon monoxide's effect on oxygen transport

combines readily, and almost irreversibly with carbon monoxide; combines with haem groups of haemoglobin to make carboxyhaemoglobin, which is a very stable compound; toxic.

functions of monosacharides

commonly used as a type of energy in respiration because of the large number of carbon-hydrogen bonds and when broken they release a lot of energy. Monosaccharides are also important as building blocks for larger molecules.

immune response

complex series of responses of the body to the entry of a foreign antigen.

virus

consists of self-replicating molecule of DNA or RNA; has protective coat of protein molecules; range from 20 nm to 300 nm in size; all viruses are parasitic because they can only reproduce by taking over living cells.

tuberculosis-prevention

contact tracing, BCG vaccine.

possible outcomes of long-term smoking

coronary heart disease (CHD), stroke, and cardiovascular diseases.

rough endoplasmic reticulum

covered with ribosomes; proteins are often modified as they move through the rough ER.

endosymbiont theory

cytoplasmic ribosomes are 80s while those of bacteria, mitochondria and chloroplasts are 70s.

sclerenchyma

dead, lignified cells for extra strength.

fluid mosaic model

described as 'fluid' because both the phospholipids and the proteins can move about by diffusion; described as 'mosaic' because it describes the pattern produced by the scattered protein molecules when the surface of the membrane is viewed from above.

translocation

describes the transport of soluble organic substances within a plant.

measles-global distribution

developing countries; places with unsanitary conditions and a high birth rate.

uses for monoclonal antibodies

diagnosis of diseases; treatments that involve modifying immune responses.

non-infectious diseases

diseases not caused by a pathogen; include inherited and genetic diseases; including degenerative diseases.

endemic

diseases that are always in populations.

infectious diseases

diseases that are caused by pathogens and are passed from infected people to uninfected people.

autoimmune diseases

diseases which arise from the body having immune responses against itself.

bronchioles

divided from bronchus; divide more to supply alveoli with air; surrounded by smooth muscle, which can contract or relax to adjust the diameter of these airways.

unsaturated

do not contain the maximum amount of hydrogen.

unsaturated lipids

double bonds between neighboring carbon atoms of fatty acids; melt easier than saturated lipids.

mucin

droplets of mucus secreted by goblet cells.

killer T-cells

during an infection, these attach themselves to infected cells and kill them.

helper T-cells

during an infection, these stimulate B cells to divide and develop into plasma cells.

metaphase

each centrosome reaches a pole; centrosomes help to organize production of the spindle microtubules; chromosomes line up across the equator of the spindle; they are attached by centromeres to the spindle.

haemoglobin oxygen carrying ability

each haemoglobin is made of four polypeptide chains(haem groups) each with the ability to carry an oxygen molecule; Hb + 4O2 → HbO8 (oxyhaemoglobin).

haem group

each haemoglobin protein contains a haem group; contains one iron atom; one oxygen molecule can bond with each iron atom; the haem group is responsible for the color of haemoglobin.

dispersive replication

each new molecule would be made of old bits and new bits scattered randomly through the molecules; not right.

structure of DNA

each nucleotide is linked to the next by covalent bonds between phosphates and sugars; two polynucleotides running anti-parallel are held together by hydrogen bonds between the bases ( A links with two to T and C links with three to G); DNA is in a double helix shape.

division of labour

each type of organelle having its own function and therefore sharing the entirety of the work between different specialized organelles.

scanning electron microscope SEM

electron beam is used to scan the surfaces of structures.

roles of triglycerides

energy reserves- important for storage product; insulator against loss of heat; metabolic source of water.

immobilized enzymes

enzyme lactase can be immobilized using alginate beads; milk is then allowed to run through the column of lactase-containing beads; the lactase hydrolyses the lactose in the milk to glucose and galactose; milk is therefore lactose free and used to make lactose free products.

carbonic anhydrase

enzyme that catalyzes: CO2 + H2O → H2CO3 (carbonic acid)

microvilli

extensions of the cell surface membrane; used to increase surface area.

secondary response

faster than the first response because there are an increased number of memory cells which divide into plasma cells and more antibodies can be produced.

triglycerides

fats and oils made of a glycerol head and three hydrocarbon tails; insoluble in water because non-polar;

malaria-clinical features

fever, anaemia, nausea, headaches, muscle pain, shivering, sweating, enlarged spleen.

tuberculosis-incubation period

few weeks or up to several years.

to find Vmax

find 1/Vmax or y-intercept→ if 1/Vmax=y then 1/y=Vmax

channel proteins

flips between two shapes; binding site is alternately open to one side of the membrane, then the other.

AIDS-clinical features

flu-like symptoms and then symptomless; opportunistic infections including pneumonia, TB and cancers; weight loss, diarrhoea, fever sweating, dementia.

lymph

fluid inside lymph vessels; virtually identical to tissue fluid, just in a different place.

cholera-methods of transmission

food-borne, waterborne.

disulfide bonds

form between cysteine molecules; strong covalent bonds; can be broken by reducing agents.

variable region

formed by the antigen-binding sites; different on each type of antibody molecule produced.

sodium-potassium pump

found in cell surface membranes of all animal cells; role is to pump three sodium ions out of the cell at the same time as allowing two potassium ions into the cell for each ATP molecule used.

extrinsic proteins

found in the inner or outer surface of the membrane; bound to intrinsic proteins or bound to inside or outside of cells or phospholipids.

malaria-incubation period

from a week to a year.

ionic bonds

from between ionized amine groups and ionized carboxylic groups; can be broken by pH changes.

oranelles

functionally and structurally distinct parts of a cell.

alveoli

gas exchange surface surface for humans; walls contain elastic fibres which stretch during inspiration and recoil during expiration to help force out air; extremely thin walls to minimize the distance of diffusion.

cell signalling

getting a message from one place to another; makes cells able to respond appropriately to their environment; signal → receptor → (transmission) → target → response; includes both electrical and chemical events; signaling is important in the cell membrane because the membrane controls what goes in an out of the cell; signalling molecules are water soluble.

vaccination

giving a vaccine containing antigens for a disease, either by injection or by mouth.

antibodies

glycoproteins made by plasma cells derived from B-lymphocytes, secreted in response to an antigen.

biological significance of mitosis

growth; replacement of cells and repair of tissues; asexual reproduction; immune response.

transcription

happens in the nucleus; code is made by building mRNA using one strand as a template; three nucleotides are joined together by RNA polymerase, this copies the DNA code onto and mRNA molecule; a complementary copy of the base sequence on a gene is made, by building mRNA against one DNA strand.

HIV/AIDS-prevention

hard to prevent; education of contraceptives; contact tracing.

tissue fluid

has almost identical composition to blood plasma; contains far fewer protein molecules; found in the spaces between cells; does not contain red blood cells.

testing for the presence of non-reducing sugars

heat solution with acid; then add BENEDICT'S solution; if color change occurs, non-reducing sugar is present.

high surface tension and cohesion

high cohesion-explains how water can move in long, unbroken columns through the vascular system; high surface tension- allows small creature to exploit the surface of water as a habitat.

centromere

holds the two chromatids together in narrow region.

AIDS-pathogen

human immunodeficiency virus

factors affecting transpiration

humidity: low humidity→more transpiration; wind speed and temperature: increase→increase; light intensity: more light→more transpiration; very dry conditions: more water loss→more transpiration.

four most common elements

hydrogen, oxygen, nitrogen, carbon

cholesterol

hydrophilic heads and hydrophobic tails; fit neatly between phospholipid molecules; much less common in plant cell membranes and absent in prokaryotes; at low temperatures, cholesterol increases the fluidity; at higher temperatures, it stabilizes cells, so the membrane isn't too fluid.

calculating microscopy

i/(a*m) i=image; a=actual; m=magnification

non-competitive inhibition

if a molecule can bind to another part of the enzyme rather than its active site it can disrupt function and while its attached the function cannot resume no matter how much of the substrate is present.

competitive inhibition

if an inhibitor molecule only briefly binds to the active site, there is competition between it and the substrate; if more substrate i present it will easily bind to active site; if more inhibitors are present , or the amount of substrates falls, it becomes less likely that that the substrate will collide with an empty site; said to be reversible.

oxyhaemoglobin

if the iron molecules of the haem group are combined with oxygen.

osmosis in animal cells

if the water potential of the solution surrounding the red blood cell is too high, the cell swells and bursts; if the water potential of the solution surrounding the red blood cell is too low, the cell shrinks; if the solution surrounding the red blood cell has the same concentration then the red cell remains normal.

polyunsaturated

if there is more than one double bond between carbon atoms.

monounsaturated

if there is only one double bond between carbon atoms.

natural immunity

immunity gained by being infected or by receiving antibodies from the other across the placenta or in breast milk.

active immunity

immunity gained when an antigen enters the body, and immune response occurs and antibodies are produced by plasma cells.

artificial immunity

immunity gained wither by vaccination or by injecting antibodies.

passive immunity

immunity gained without an immune response; antibodies are injected or pass from mother to child across the placenta or in breast milk.

Casparian strip

impenetrable suberin barrier to water in the walls of the endodermis cells.

malaria-global control

improvements by use of modern techniques in gene sequencing and drug design, development of vaccines targeted against different stages of the parasite's life, a renewed international will to remove the burden of disease from the poorest parts of the world, allied to generous donations from wealthy individuals and foundations.

osmosis in plant cells

in dilute solutions, plant cells do not burst, because the cell wall provides resistance to prevent it from expanding; this adds pressure which is turgid plasmolysis happens when the outside solution is more concentrated than the solution within the cell.

prophase

in early prophase chromosomes start to appear as the chromatin coils up, becoming shorter and thicker; they are thick enough to become visible when stained; in late prophase, nuclear envelope disappears; nucleolus disappears; centrosomes moving to opposite ends of the nucleus where they form the poles of the spindles; at the end of prophase a spindle is formed.

AIDS-methods of transmission

in semen and vaginal fluids during sexual intercourse, infected blood or blood products. contaminated hypodermic syringes, mother to fetus across placenta, at birth, mother to infant in breast milk.

the number of white blood cells

increases in the blood during bacterial infections and whenever tissues become inflamed and die; help to determine if a disease is present.

emphysema

inflammation → elastase eats elastic in alveoli wall → cannot recoil or expand as much → bronchioles collapse during respiration → large spaces appear → reduced surface area for gas exchange → less oxygen absorbed in the blood → hard to breathe.

reversible

inhibition can be reversed by increasing the concentration of the substrate.

AIDS-incubation period

initial incubation a few weeks, but up to ten years or more before symptoms of AIDS may develop.

tunica intima

inner endothelium; flat cells fitting together; very smooth for minimal friction.

malaria-method of transmission

insect vector: female Anopheles mosquito.

products

interaction between the R groups of the enzyme and the atoms of the substrate can break, or encourage formation of, bonds in the substrate molecule, forming one, two or more products.

how antibiotics work

interfere with some aspect of growth or metabolism in the target bacterium: synthesis of bacterial walls, activity of proteins in the cell surface membrane, enzyme action, DNA synthesis, protein synthesis.

S phase

interphase stage where DNA replicates so that each chromosome consists of two identical chromatids.

G2 phase

interphase stage where cell continues to grow and new DNA is checked and any errors are repaired; preparations for cell division are made.

G1 phase

interphase stage where cells make the RNA, enzymes and other proteins needed for growth; by the end of G1, the cell becomes committed to dividing or not dividing.

the three phases of the cell cycle

interphase, nuclear division, and cell division.

how is water transported from soil into root hair?

into root hairs via osmosis down a water potential gradient.

tuberculosis-treatment

isolation during most contagious period; several drugs are used to ensure that all the bacteria are killed.

high specific heat capacity

its more difficult for the molecules in water to move faster because of hydrogen bonds that make the molecules stick together; bonds need to be broken to allow more movement which explains why water has such a high heat capacity; water is more resistant to changes in temperature.

semilunar valves

keep blood flowing in the correct direction by preventing back flow.

cartilage

keeps the trachea and bronchi open and air resistance low; prevents trachea and bronchi from collapsing or bursting as the air pressure changes during breathing.

smooth endoplasmic reticulum

lacks ribosomes; makes lipids and hormones.

how the nature of the molecules affects diffusion

large molecules require more energy to get them moving than small ones do, so large molecules tend to diffuse more slowly than small molecules.

aorta

large, arching blood vessel which is the largest artery.

T-lymphocytes

leave the bone marrow and collect in the thymus here they mature.

high altitude's affect on oxygen transport

less oxygen is available, therefore less oxygen is carried around the body, and the person may become breathless and ill; altitude sickness; over a period of time, the number of red blood cells increases; people born and raised in these conditions develop broad chests, large lungs and a larger heart.

peptide bond

link between a carbon atom of the first amino acid and the nitrogen atom of the second; caused by the removal of a water molecule through the condenstion reaction.

capillaries

links arteries and veins; function is to take blood as close to all cells as possible, allowing rapid transfer of substances between cells.

phloem sap

liquid inside phloem sieve tubes.

malaria-site of action

liver, red blood cells, brain.

active loading

loading high concentrations of sucrose into a sieve element greatly decreases the water potential in the sap inside it → water enters sieve element → high buildup of pressure → causes mass flow.

xylem vessel

long continuous tube of vessel elements.

root hairs

long, thin extensions of the epidermis; increases the surface area and therefore increasing the rate at which water can be absorbed.

β-pleated sheet

looser, straighter shape than the α-helix; hydrogen bonds also keep this in its shape.

translation

mRNA moves to a ribosome in the cytoplasm; tRNA molecules with complementary triplets of bases temporarily pair with base triplets on the mRNA, bringing appropriate amino acids; when to amino acids are held side by side a peptide bond forms between them; the ribosome moves along the mRNA molecule so that the appropriate amino acids re gradually linked together. following the sequence made by the base sequence on the mRNA.

amylose

made by condensations between α-glucose molecules; large, unbranching chain of several thousand 1,4 linked glucose molecules; the chains are curved and coil into helical structures, making the final molecule more compact.

xylem tissue

made from cells joined end to end to form tubes; cells are dead; walls of the cells are thickened with lignin; many functions are support and transport.

cardiovascular system

made of a pump, the heart, and a system of interconnecting tubes, the blood vessels.

sieve tubes

made of living cells; joined end to end vertically to form a continuous tube; very little cytoplasm and no nucleus or ribosomes; contains sieve plates.

amylopectin

made of many 1,4 linked α-glucose molecules, but the chains are shorter than amylose and branch out to the sides; the branches are formed by 1,6 linkages.

parenchyma

made of thin-walled calls used as packing tissue; used for storage of foods like starch; forms the cortex of roots and stems; contains chloroplasts.

bilayers

made of two micelle structures layered together; it is known that the phospholipid bilayer is the basic structure of membranes.

glycogen

made up f 1,4 linked α-glucose chains with 1, linkages forming branches; more branched than amylopectin; found in animals and is used as the storage carbohydrate.

mesophyll

made up of specialized parenchyma cells found between the lower and upper epidermis of the leaf; there are two types: spongy and palisade.

xylem

mainly carries water and inorganic items from roots to parts above ground; can only move in one direction.

antigenic shift

major changes in antigen structure, which makes the antigen more difficult to recognize.

water

major component of cells, compromising 70%-95% of the cell's mass; provides environment for water-living organisms; hydrogen bonding of water makes i difficult to separate and affects the physical properties of water; H2O.

microtubules

make up cytoskeleton; made of tubulin.

polypeptide

many amino acids linked together.

monoclonal antibodies

many identical antibodies, made by hybridoma cells.

the course of a reaction

many substrates; every enzyme full and busy → when substrates begin to decrease the reaction slows down because enzymes are waiting for substrates because the substrates have been converted into products → reaction slows and eventually stops.

how translocation occurs

mass flow by the difference of pressures; plant has to use energy to create pressure differences needed for mass flow; produced by active loading.

external defense system

mechanisms which protect us against infectious diseases: epithelia which covers pathways; hydrochloric acid in the stomach; blood clotting.

immunological memory

memory cells are able to recognize the antigens which is the main reason the immune system is effective.

loading sucrose into phloem

mesophyll cell → symplastic or apoplastic → into companion cell → hydrogen atoms are pumped out of the cell → sucrose carried against concentration gradient by co-transporter → from companion cell to sieve tubes via plasmodesmata.

cholera-method of diagnosis

microscopical analysis of faeces.

malaria-method of diagnosis

microscopical examination of blood; dip stick test for malaria antigens in blood.

tuberculosis-methods of diagnosis

microscopical examination of septum for bacteria, chest x-ray.

tunica media

middle layer; contains smooth muscle. collagen and elastic fibres.

antigenic drift

minor changes in an antigen that still cause an immune response because the memory cells will still recognize them.

cell surface antigens

molecules on the surface of our cells that are not found in other organisms.

non-polar

molecules which do not have groups with dipoles.

polar

molecules which have groups with dipoles.

amino acids

monomers of protein.

proteins

more than 50% of the dry mass of mot cells is protein; monomers are nucleic acids.

cellulose

most abundant organic molecule on the planet; polymer of β-glucose; every other monomer must rotate 180 degrees i order to bond with next molecules, this arrangement results in a strong molecules because of the many hydrogen bonds; structure: cellulose molecules--microfibrils--fibres--cell wall; freely permeable despite strength.

collagen

most common protein in mammals; insoluble fibrous protein; consists of three polypeptide chains, each in the shape of a helix; wound together to form a three-stranded 'rope' structure; covalent bonds form between the R groups lying next to each other; flexible but very strong; line up to withstand forces.

pH and enzyme activity

most enzymes function at fairly neutral pH conditions; if pH gets too high or low enzyme will become denatured.

tuberculosis-pathogen

mycobacterium tuberculosis; mycobacterium bovis.

HIV/AIDS-treatment

no cure or vaccine; drug therapy can only slow it down.

measles-incubation period

no symptoms for 8-14 days.

pits

non-lignified 'gaps' in the thick walls of the xylem vessel.

hydrophobic

not attracted to water.

telophase

nuclear envelope re-forming; nucleolus re-forming; chromatids have reached the poles of the spindle; they will now uncoil again; cytokinesis; remains of spindle is breaking down.

hydrophobic interactions

occur between non-polar R groups; although interactions are weak, the groups tend to stay together because they are repelled by the watery environment around them.

pandemic

occurs when there is an increase in the number of cases throughout a continent or across the world.

endodermis

one cell thick and surrounds the vascular tissue in stems and roots.

conservative replication

one completely new double-helix would be made from the old one; not right.

cancer

one of the most common diseases of developed countries; cancerous cells divide repeatedly and form a tumour.

chromatids

one of two identical pats of a chromosome, held together by a centromere, formed during interphase by the replication of the DNA strand.

centriole

one of two small, cylindrical structures, made from microtubules, found just outside the nucleus in animal cells, in a region known as the centrosome they are also found in the bases of cilia and flagella.

complementary base pairing

one pyrimidine pairs up with a purine base; specifically A with T and C with G; U replaces T where RNA is concerned.

cholera-treatment

oral rehydration therapy; combination of salts given intravenously.

compartmentalism

organelles themselves being surrounded by membranes so that their activities can be separated from the surrounding cytoplasm.

prokaryote

organisms that lack nuclei; usually 1000 x - 10000 x smaller in volume than eukaryotes; DNA is circular and free in the cytoplasm; known as simplest cells; contain 70s ribosomes.

pathogens

organisms which cause an infectious disease.

eukaryote

organisms who possess nuclei; includes plants, animals, fungi and unicellular organisms known as protoctists; DNA is linear and bound to proteins to form chromatin.

memory cells

other B-cells become these; they remain in the body for a long time; if the same antigen is reintroduced to the body, these will divide rapidly so the infection can be destroyed and removed before any symptoms of disease develop.

pulmonary artery

other blood vessel leaving heart other than aorta; this one goes to lungs.

tunica externa

outer layer; contains elastic fibres and collagen fibres.

haemoglobin

oxygen-carrying pigment found in red blood cells; is a globular protein; it is made of four polypeptide chains-each chain itself is known as globin; the chains consist of two α-chains made of α-globin and two chains made of β-chains made of β-globin.

blood plamsa

pale yellow liquid where cells float; mostly water with a variety of substances dissolved in it, includes plasma proteins.

oncogene

particular term for a mutated gene that causes cancer.

carrier

people who lack symptoms but are able to transmit the disease.

types of white blood cells

phagocytes and lymphocytes.

the contents of phloem sieve tubes

phloem sap; high pressure.

atrioventricular node

picks up the signal sent by the sinoatrial node and after a delay sends it to the purkyne tissue.

xerophytes

plants with special adaptations of their leaves to keep water i because the live in places where water supply is short.

horizontal transmission

plasmids get transferred from one bacterium to another through conjugation and then both bacteria are resistant.

malaria-pathogen

plasmodium falciparum; plasmodium vivax; plasmodium ovale; plasmodium malariae.

stomata

pores in leaves which allow entry for carbon dioxide for photosynthesis.

hydrostatic pressure

pressure exerted by a liquid.

penicillin

prevents the synthesis of cross-links between peptidoglycan polymers n the cell walls of bacteria by inhibiting the enzymes that build these cross-links.

tuberculosis-site of action

primarily infection in lungs; secondary infection in lymph nodes, bones and gut.

goblet cells

produces mucus; embedded in the ciliated epithelium.

The four stages of mitosis

prophase, metaphase, anaphase, and telophase.

enzymes

protein molecule defined as a biological catalyst; many enzymes end with the suffix -ase; for example: lipase, carbonic anhydrase, and protease are enzymes.

fibrous protein

protein molecules that form long strands; usually not soluble in water; examples would be keratin or collagen.

structural protien

protein that improves or increase structural ability; for instance: collagen in animals and cellulose in plants.

intrinsic proteins

proteins that are found embedded within the membrane; transmembrane proteins; hydrophobic regions are repelled by water and therefore stay within the membrane; hydrophilic regions are repelled by the hydrophobic interior and therefore face the aqueous environment in or out of the cell.

transmembrane proteins

proteins the span the entire membranes; hydrophobic regions which cross the membrane are often made up of one or more α-helical chains.

transport proteins

provide hydrophilic channels or passageways for ions and polar molecules to pass through the membrane; two types of transport proteins would be channel proteins and carrier proteins.

double circulation

pulmonary circulation and systemic circulation: heart to lungs to hear to est of body to heart.

tuberculosis-clinical features

racking cough, coughing blood, chest pain, shortness of breath, fever, sweating, weight loss.

root pressure

raised by the active secretion of solutes; cells surrounding the xylem vessels pump solutes across their membranes and int the xylem by active transport; the influx of water to reach equilibrium increases the water pressure at the base of the xylem vessel.

measles-clinical features

rash, fever, runny nose, a cough, red and watery eyes, small white spots may develop inside the cheeks.

the effect of enzyme concentration

reaction rate is directly proportional to enzyme concentration; the more enzyme present, the more active sites available for the substrate to use; as long as there are plenty of substrate available, the initial rate of reaction increases linearly with enzyme concentration.

malaria-prevention

reduce the number of mosquitoes; avoid being bitten by mosquitoes; use drugs to prevent the parasite infecting people; biological control measures: stocking ponds, irrigation and drainage ditches and other permanent bodies of water with fish which feed on mosquito larvae; spraying a preparation containing the bacterium Bacillis thuringiensis, which kills mosquito larvae but is not toxic to other forms of life.

non-self

refers to any substance or cell that is recognized by the immune system as being foreign and will stimulate an immune response.

self

refers to any substances produced by the body that the immune system does not recognize as foreign, so they do not stimulate an immune response.

high latent heat of vapourisation

relatively large amounts of energy are needed for the hydrogen bonds between molecules to break so that the molecules can escape as a gas.

B-lymphocytes

remain in the bone marrow until they are mature and the spread throughout the bod, concentrating in lymph nodes and spleen.

gametes

reproductive cells.

vertical transmission

resistant bacteria replicate through binary fission, each daughter cell receiving a copy of the chromosome.

cardiac cycle

sequence of events which make up one heartbeat; atrial systole → ventricular systole → ventricular diastole.

codon

sequence of three bases on an mRNA molecule that codes for a specific amino acid or for stop signal.

anticodon

sequence of three unpaired bases on a tRNA molecule that binds with the codon on mRNA.

cholera-clinical features

severe diarrhoea, loss of water and salts, dehydration, weakness.

features of red blood cells

shaped like a disc; very small; very flexible; no nucleus, no mitochondria and no endoplasmic reticulum.

ribosomes

sites of protein synthesis; found in cytoplasm or on the rough ER.

inhibitor

slows down or stops an enzyme catalyzed reaction.

lymph nodes

small swellings found in intervals in the lymph vessels; involved in the protection against disease.

nucleotides

smaller molecules from which DNA and RNA are made of; they consist of a nitrogen-containing base, a pentose sugar and a phosphate group.

density and freezing properties

solid form is less dense than liquid form; therefore ice floats on top of water and insulates the water under it.

assimilates

soluble, organic substances made by the plant through photosynthesis in the leaves.

problems with vaccines

some people do not respond well to vaccinations, if at all; could accidentally spread the actual disease; there are variations in antigens.

extracellular

something not within the cell; enzymes that have been secreted by cells and catalyze reactions outside of the cell are said to be extracellular.

intracellular

something within the cell; for example enzymes that operate within cells are intracellular.

sinoatrial node

special patch of muscle in the wall of the right atrium which initiates the cardiac cycle.

osmosis

special type of diffusion involving water molecules only; the movement f water molecules from a dilute solution to a concentrated solution, through a partially permeable membrane.

how the smallpox eradication programme succeeded

stable virus; vaccine made from harmless live strain; easily kept vaccine; easy to identify the infected; virus did not effect animals; smallpox virus did not linger in body.

multipotent

stem cells that can produce a few types of cell are described as this.

totipotent

stem cells that can produce any type of cell are described as this.

pluripotent

stem cells that can produce several types of cells are described as this.

nicotine's effect on the cardiovascular system

stimulates the nervous system to reduce diameter of arterioles and release adrenaline → heart rate and blood pressure increases and blood supply decreases; also increases the risk of blood clotting; highly addictive drug.

lignin

strong, waterproof material.

telomeres

structures that seal the ends of chromosomes; made of DNA with short base sequences that are repeated many times; main function is to ensure that the ends of the DNA are included in replication.

unloading sucrose from phloem

sucrose moves out of the phloem tissues via the apoplastic or symplastic pathways → once in tissue, sucrose converts into something else by enzymes.

epidemic

sudden increase in the number of people with a disease.

glycocalyx

sugary coating to the cell formed by carbohydrate chains; mainly glycolipids in plants; mainly glycoproteins in animals.

chronic bronchitis

tar inhibits ciliated epithelium → accumulation of mucus → obstruction → damaged epithelium replaced with scar tissue → thickens airways → infection leads to inflammation → narrow airways → bronchitis.

ingredients in tobacco smoke

tar, carbon monoxide, nicotine.

AIDS-method of diagnosis

testing blood, saliva, or urine for the presence of antibodies produced against HIV.

resolution

the ability to distinguish between two objects very close together; the higher the resolution of an image, the greater the detail that can be seen.

arterioles

the arteries branch into these smaller vessels.

cell theory

the basic unit of structure and function of all living organisms is the cell.

closed blood system

the blood always remains inside the vessels.

immune system

the body's internal defense which provides protection against disease.

oedema

the build up of fluid resulting from a too high of blood pressure which makes too much fluid to be forced out of the capillaries.

endocytosis

the bulk movement of liquids or solids into a cell, by the infolding of the cell surface membrane to form vesicles containing the substance; endocytosis is an active process requiring ATP.

exocytosis

the bulk movement of liquids or solids out of a cell, by the fusion of vesicles containing the the substance with the cell surface membrane; exocytosis is an active process requiring ATP.

pinocytosis

the bulk uptake of liquid.

phagocytosis (transport)

the bulk uptake of solid material.

zygote

the cell formed when two gametes from your parents fused.

ester bond

the chemical link between the acid and the alcohol; made by condensation reaction.

ester

the chemical produced in the reaction between an acid and an alcohol.

enzyme-substrate complex

the combined structure of the enzyme and the substrate which is held in place by temporary bonds which form between the substrate and some of the R groups of the enzyme's amino acids.

tertiary structure

the compact structure of a protein molecule resulting from the three-dimensional coiling of the already-folded chain of amino acids.

cytoplasm

the contents of a cell, excluding the nucleus.

pressure potential ( Ψp)

the contribution of pressure to the water potential; increasing the pressure of a solution increases the tendency of water to move out of it, that increases water potential.

solute potential (Ψs)

the contribution of the concentration of the solution to water potential; the extent to which the solute molecules decrease the water potential of the solution; the more solute there is, the lower the tendency for water to move out of the solution.

mortality

the death rate from different diseases.

facilitated diffusion

the diffusion of a substance through transport proteins in a cell membrane; he proteins provide hydrophilic areas that allow the molecules or ions to pass through the membrane which would otherwise be less permeable to them; proteins involved are carrier and channel proteins.

antigen presentation

the display of antigens on the surface of cells that act as a signal.

cytokinesis

the division of the cytoplasm and the cell into two by constriction from the edges of the cell.

potency

the extent of the power of a stem cell to produce different cell types.

activation energy

the extra energy needed for a substrate in chemical reactions to be converted into a product; enzymes educe the activation energy needed for a reaction to take place therefore speeding up the rate of reaction.

β-glucose (beta-glucose)

the form of glucose where the hydroxyl group -OH is above the plane of the ring.

α-glucose (alpha-glucose)

the form of glucose where the hydroxyl group -OH is below the plane of the ring.

why don't plants need transport systems for gases?

the gases carbon dioxide and oxygen diffuse through air spaces within stems, roots and leaves.

how the 'steepness' of the concentration gradient affects diffusion

the greater the difference in concentration, the greater the difference in the number of molecules passing in the two directions, and hence the faster the rate of diffusion.

how the surface area affects the diffusion

the greater the surface area, the more molecules or ions can cross it at any moment, and therefore the faster diffusion can occur.

polyribosomes

the group of ribosomes working on the same mRNA molecule.

cardiac muscle

the heart.

denatured

the hydrogen bonds of the enzyme begin to break; enzyme molecule begins to lose its shape and can no longer function.

lock and key hypothesis

the idea that the enzyme has a particular shape into which the substrate fits exactly.

stem cell therapy

the introduction of new adult stem cells into damaged tissue to treat disease or injury.

protoplast

the living contents of a plant cell, including the cell surface membrane, but excluding the cell wall.

transpiration

the loss of water vapor from a plant to its environment, by diffusion down a water potential gradient; most transpiration takes place through the stomata in the leaves.

ventricles

the lower chambers on each side of the heart; blood comes from atria and is squeezed into the arteries.

homeostasis

the maintenance of a constant internal environment.

substrate

the molecule that binds to the active site.

factors that make the membrane less fluid

the more saturated the phospholipid tail; the longer the phospholipid tail; a decrease in temperature.

active transport

the movement of molecule or ions through transport proteins across a cell membrane, against their concentration gradient, using energy from ATP.

diffusion

the net movement, as a result of random motion of its molecules and ions, of a substance from a region of its higher concentration to a region of its lower concentration; the molecules or ions move down a concentration gradient;

incidence

the number of people who are diagnosed over a certain mount of time.

prevalence

the number of people who have that disease at any on time.

magnification

the number of times greater that an image is than the actual object

R group

the only way in which amino acids differ from one another; there are 20 different R groups which means 20 different amino acids.

mitochondria

the organelle in eukaryotes in which aerobic respiration takes place; synthesizes lipids.

optimum pH

the pH at which an enzyme can function at its maximum rate.

the dissociation curve

the percent saturation of haemoglobin plotted against the partial pressure of oxygen.

the Bohr shift

the presence of high partial pressure of carbon dioxide causes haemoglobin to release oxygen.

plasmolysis

the protoplast shrinks because the plant cell was placed in a solution of lower water potential, as the protoplast continues to shrink it pulls away from the cell wall.

initial rate of reaction

the rate of an enzyme-controlled reaction is always the fastest at the beginning.

primary structure

the sequence of amino acids in a polypeptide or protein.

the triplet code

the sequence of nucleotide bases in a DNA molecule is a code for the sequence of amino acids in a polypeptide; each sequence of three bases stands for one amino acid.

metastasis

the spread of cancer through secondary growth.

secondary stucture

the structure of a protein molecule resulting from the regular coiling or folding of the chain of amino acids.

optimum temperature

the temperature at which an enzyme catalyzes a reaction at the maximum rate.

water potential ( Ψ)

the tendency of water to move out of a solution; water always moves from a region of high water potential to a region of low water potential; increasing the pressure on a liquid will increase the tendency for water to move out of it, which is increasing its water potential.

quanternary structure

the three-dimensional arrangement of two or ore polypeptides, or of a polypeptide and a non-protein component such as haem, in a protein molecule.

bulk transport

the transport of large quantities of material into or out of cells; a form of active transport.

nuclear envelope

the two membranes surrounding the nucleus; the outer membrane of the nuclear envelope is continuous with the endoplasmic reticulum.

atrium

the upper chamber on each side of the heart; receive blood from the veins.

septum

the wall of muscle that separates the two chambers in the heart.

transmission cycle

the way in which a pathogen passes from one host to another.

electromagnetic spectrum

the whole range of different wavelengths.

types of nitrogen-containing bases

there are five different kinds: adenine (A), thymine (T), guanine (G), cytosine (C), and uracil (U); in DNA there is A,T,G,C; in RNA there is A,U,G,C; purine bases are A and G; pyrimidine bases are C, T and U.

features of a genetic moleule

they have the ability to carry instructions; they have the ability to be copied over and over again perfectly.

suberin

thick, waterproof, waxy band in cell walls.

primary response

this stage in the infection where there are very few B cells that are specific to the antigen.

malaria-global distribution

throughout the tropics and sub-tropics.

lymph vessels

tiny, blind-ending vessels, which are found in almost all tissues of the body; tiny valves which allow inflow but not outflow, wide enough to allow large protein molecules to pass through; smooth muscle in their walls.

transport needs of plants

to move substances from where they are absorbed to where they are needed; to move substances from where they are produced to where they are needed; to move substances to different parts of the plant.

protein synthesis

transcription → translation → protein (polypeptide)

purkyne tissue

transmits the wave sent from the atrioventricular node to the septum, which is where it spreads to the walls of the ventricles.

sieve elements

transports assimilates.

xylem vessel elements

tubes in the xylem made from dead cells.

malignant tumours

tumours that spread through the body, invade other tissues and destroy them, causing cancer.

the three layers of veins and arteries

tunica intima, tunica media, tunica externa.

isomers

two forms of the same chemical.

cholera-incubation period

two hours to five days.

venae cavae

two large veins that run vertically on the right side; one brings blood downward from the head and the other bringing it upwards from the rest of the body.

dipeptide

two linked amino acids.

semi-conservative replication

two strands of the DNA molecule could split apart → new nucleotides would line up along each strand → join to form completely new and complementary strands along each half of the original molecule; half of the original molecule is kept in each of the new molecules.

measles-site of action

upper respiratory tract.

water as a reagent

used in chemical reaction; photosynthesis; also essential for hydrolysis reactions.

how to reduce resistance

using antibiotics only when appropriate and necessary not prescribing them for viral infections; reducing the number of countries in which antibiotics are sold without a doctor's prescription; avoiding the use of so-called wide spectrum antibiotics and using instead an antibiotic specific to the infection; making sure that patients complete their course of medication; making sure patients due not keep unused anti-biotics for self-medication for the future; changing the type of antibiotics prescribed for certain diseases so that the same antibiotic is not always prescribed for the same disease; avoiding using antibiotics in farming to prevent, rather than cure, infections.

herd immunity

vaccination of a large number of people within a given area at the same time; interrupts transmission in a population, so that those who are susceptible never encounter the infectious agents concerned.

pulmonary veins

veins that bring blood back to the heart from the left and right lungs.

arteries

vessels that carry blood away from the heart; function is to transport blood swiftly and at high pressure; their walls are strong and elastic; thickest walls of any blood vessels.

veins

vessels that carry blood towards the heart; low pressure of the returning blood can cause issues with the flow of blood→ reason for valves.

cholera-pathogen

vibrio cholerae.

measles-pathogen

virus.

cholera-site of action of pathogen

wall of small intestine.

passage cells

water can pass through these freely; found in endodermis of plant cells.

how is water transported from xylem across leaf?

water evaporates from cell walls of mesophyll cells→ water travels from xylem to leaf→ water then moves from cell to cell in the lead by two pathways: symplastic or apoplastic.

carrier proteins

water filled pores; have fixed shape; allow charged substances to move through the membrane; most are gated, the part of the protein on the inside of the membrane can move to open or close the protein- allows for control of ion exchange.

water as a transport medium

water is the transport medium in the blood, in the lymphatic, excretory and digestive systems of animals; transport medium in vascular system of plants.

cohesion

water molecules are attracted to each other by hydrogen bonding.

water as a solvent

water molecules re attracted to ions and polar molecules and therefore collect around them and separate them which is what happens when a chemical dissolves in water.

symplastic pathway

water moves from cell to cell via plasmodesmata; enters cytoplasm by osmosis → into sap in the vacuole → may use plasmodesmata or adjacent cell surface membranes or walls to travel between cells.

apoplastic pathway

water moves through the cell walls; enters cell wall → through cell wall → may move using intracellular space between or directly cell wall to cell wall.

how is water transported from root hair to xylem?

water taken up by root → crosses cortex → enter xylem; in short follows potential gradient; apoplastic or symplastic movement; when water reaches endodermis, path is blocked → cytoplasm of endodermal cells →down water potential gradient and across pericycle → into the xylem through pits → then up vessels.

turgid

when a plant cell is fully inflated with water.

α-helix

when a polypeptide chain coils into a corkscrew shape; a type of secondary structure; due to the hydrogen bonding holding the chain firmly in shape.

antibiotic resistance

when bacteria gain a gene coding for a protein that protects them from an antibiotic.

secondary growth

when cells break off and spread through the blood and lymphatic system to other parts of the body and begin to grow there.

immunity

when people experience few to no symptoms when exposed to certain infectious diseases.

micelles

when phospholipids are shaken up with water, they can for stable ball-like structures; here all of the hydrophilic heads point outwards into the water, shielding the hydrophobic tails, which point in towards each other.

sickle cell anaemia

when the base sequence CTT is replaced by CAT the amino acid sequence changes; This codes Hb^s and two copies of this allele results in the disease sickle cell anaemia.

gas exchange surface

where oxygen from the external environment can diffuse into the body, and carbon dioxide can diffuse out; in humans → alveoli.

sieve plate

where the ends of two sieve elements meet this forms; made up of the walls of both elements containing large pores.

differences between red blood cells and white blood cells

white blood cells have a nucleus whereas red blood cells do not; white blood cells are larger than red blood cells; white blood cells are either spherical or irregular whereas red blood cells are shaped like discs.

fibrillation

without the coordination of the pulse the heart will just flutter and will be unable to pump blood to the body; fatal.

AIDS-global distribution

worldwide, especially in sub-Saharan Africa and South-East Asia.

tuberculosis-global distribution

worldwide.

differences between sieve tubes and xylem vessels

xylem has dead vessels, phloem has live vessels; sucrose would leak out of xylem because lack of membrane; xylem has lignified wall; end walls of xylem disappear whereas phloem has sieve plates; phloem can heal itself rapidly; xylem can withstand high negative pressure whereas phloem can withstand high positive pressure.