OCR A Level Biology Summer Assessment 2

(iv) Suggest *two* reasons why governments in parts of the world other than tropical areas, are also becoming increasingly concerned about malaria.

- climate change may result in spread to other parts of the world - increased movement of infected people - non-malaria countries fund anti-malaria measures via international aid - resistance of parasites to drugs/mosquito to insecticides

Celery contains the enzyme catalase, which breaks down hydrogen peroxide into oxygen and water. A student added liquidised celery to a solution of hydrogen peroxide and collected the oxygen given off by the reaction. The results are shown in the graph below. Which of the following shows the rate of reaction at 30s?

A: 0.85cm3s-1

The first stage of primary succession is the pioneer community. Which of the following statements about a pioneer community are correct?

A: 1, 2 and 3 (1. species produce large numbers of wind-carried seeds or spores 2. biomass is low 3. many species are lichens and mosses)

Which of the following best describes a microscope with high resolution?

A: The microscope can distinguish structures that are very close together.

Which of the following describes an autoimmune disease?

A: a disease in which an individual's own body cells are antigenic

(b) People with the disease known as iron-deficient anaemia (IDA) are resistant to malaria. This resistance is not well understood but is thought to involve phagocytosis. Fig. 2.1 shows the process of phagocytosis of a pathogen by a phagocyte. (i) Identify the structures represented by the letters A, B, C and D.

A: antigen B: extension of cytoplasm C: lysozome D: phagocytic vesicle

Which of the following statements about gene therapy is not correct?

A: changes resulting from gene therapy cannot be passed on to offspring

Lipids are a diverse group of chemicals that are neither polar nor charged and hence are insoluble in water. The ... nature of the heads of phospholipids allows them to form membranes. ... also contain fatty acids and form part of the membrane. Lipids can be used for energy storage in the form of ... Some hormones are also lipids and they are similar in structure to ... Which row shows the correct sequence of missing words?

A: hydrophilic, glycolipids, triglycerides, cholesterol molecules

Which of the statements, A to D, about amylopectin is correct?

A: it contains 1-4 and 1-6 glycosidic bonds between alpha-glucose monomers

Which of the following processes involves the formation of ester bonds?

B: Only 1 and 2 (1. synthesis of polynucleotides 2. synthesis of triglycerides)

Cut pieces of agar jelly can be used to investigate the factors affecting diffusion rates in cells. Four pieces of agar jelly containing universal indicator were soaked in the same concentration of hydrochloric acid for one minute. The cubes were then removed and blotted dry. Which of the following pieces of agar jelly would be the first to turn entirely red?

B: a cuboid with edges 2cm, 4 cm and 6cm

The photograph below shows a blood smear. Which row correctly lists the cells that are visible in the smear?

B: erythrocytes v lymphocytes x monocytes x neutrophils v

Which of the options, A to D, is a primary defence against pathogens?

B: inflammation

Which of the statements, A to D, best defines the term species evenness?

B: the relative abundance of each species in an area

Which of the following could *not* be an amino acid?

C

The haploid chromosome number in the koala, Phascolarctos cinereus, is 8. Independent assortment of chromosomes in meiosis contributes to genetic variation in the gametes of the koala. How many genetically different versions of koala gamete would it be possible for one individual to produce if independent assortment were the only source of genetic variation?

C: 256

The image below shows a tardigrade, Echiniscus granulatus, viewed from underneath. The magnification is x110. How long is the tardigrade in real life?

C: 8.64 x 10-4m

The adult wandering albatross, Diomedea exulans, has wingspans that range from 2.5m to 3.5m. Which of the following describes the variation in wingspan of the wandering albatross?

C: intraspecific and controlled by both genetic and environmental factors

Membranes are found within and surrounding cells. Which of the statements, A to D, is not a role of membranes in cells?

C: provides support for cell

Mycopeotein is a food produced by the fungus Fusarium venenatum. Which statement about mycoprotein is correct?

C: waste products can be used as a substrate

The diagram below shows part of a plasma membrane. Which of the label lines points to a structure that could contain a sulfur atom?

D: Only 1

Which of the following processes occur during DNA replication?

D: Only 1

The image below shows a European badger, Meles meles, which is a member of the family Mustelidae. The American badger belongs to a different genus within the same family. Which of the options, A to D, is the correct binomial name for the American badger?

D: Taxidea taxus

A teacher wrote: "A garden pond is a dynamic environment that is home to a variety of organisms. The temperature of the pond varies depending on the weather and the time of year, and this affects the populations of the species that live there." Which of the following terms applies to the teacher's description of the garden pond?

D: a niche

Hox genes contribute to the overall body plan of an animal. Which of the following rows correctly describes Hox genes?

D: similar in all animals, polypeptide, are often lethal

During which stage of the cell cycle does semi-conservative DNA replication take place?

D: synthesis phase

Crude oil contains hydrocarbons. Three hydrocarbons commonly present in crude oil are shown in Fig. 22. Compound W shows some structural similarities with fatty acids. State one structural difference between compound W and a saturated fatty acid.

Fatty acids contain a carboxyl (COOH) group in their chain

Explain how DNA sequencing allows the sequence of amino acids in a polypeptide to be predicted.

The sequence of bases codes for the sequence of amino acids (as each triplet codon codes for one amino acid)

Hospitals can check to see if a strain of bacteria causing an infection is resistant to a range of antibiotics by using a multodisc. A multodisc contains different antibiotics. - The bacteria are isolated from a patient. - The bacteria are spread on nutrient agar in a Petri dish. - The multodisc is placed on the agar. Fig. 3.3 shows a Petri dish with the bacteria, in which is placed a multodisc containing six different antibiotics. (i) Explain why there are clear areas of agar in the Petri dish.

This is where the antibiotic has been effective in killing bacteria

Plants rely on osmosis for support. Explain the importance of osmosis in plant support.

Water moves into cells down a water potential gradient, increasing the hydrostatic pressure on the cell wall (the cell becomes turgid). Without osmosis the plant cells would be flaccid and unable to maintain their shape (e.g. stomata would be unable to open)

The enzyme DHPS is involved in the production of folic acid in bacteria. - The substrate for DHPS is a molecule known as PABA. - The enzyme DHPS is inhibited by the drug sulfonamide. Fig. 3.1 shows the structure of PABA and that of sulfonamide. (i) Diagrams X, Y and Z represent these enzyme molecules and their active sites. State the letter, X, Y or Z, that most accurately represents the enzyme DHPS.

X

The use of antibiotics as growth promoters in animal production was banned in the European Union in 2006. Suggest a concern that led to this ban.

antibiotic resistance

Charles Darwin sailed on HMS Beagle on its voyage around the world between 1831 and 1836. (a) Darwin made the following observation: 'offspring generally appear similar to their parents' State the conclusion that Darwin drew from this observation.

characteristics are passed on to/inherited by the next generation

(ii) In patients with IDA, anaemia is caused by the destruction of erythrocytes (red blood cells) by phagocytosis. Suggest why erythrocytes that contain Plasmodium are more likely to be destroyed by phagocytosis than healthy erythrocytes.

different chemicals that attract phagocytes releases from infected phagocytes

Suggest one adaptation, visible in Fig. 1.1 and Fig. 1.2, which would be useful for an animal that lives on the sea bed.

eyes on top of head

Other evidence used to estimate the jaguar population includes footprints and reports of sightings by local humans. Suggest one disadvantage of each of these methods for estimating the size of the jaguar population.

human sightings: - misidentification - seeing the same individuals twice/ exaggeration/ lying/ poor recollection/ jaguars likely to be where humans are not footprints: - might disappear before recording / multiple pairs in same spot makes counting difficult/ same print might be counted on different occasions

(iii) Suggest why malaria is much more common in tropical areas than in other parts of the world.

more mosquitoes (vectors) in hotter climates

Using Fig. 3.3, name the antibiotic that is mist effective against the bacteria causing the infection.

streptomycin

Which of the following antibodies increase(s) the phagocytosis of pathogens?

B: Only 1 and 2 (1. opsonins 2. agglutinins)

Suggest three reasons why a hospital might use a multidisc to select the most suitable antibiotic for treating a patient.

- cheap - test is quick - comparison to other antibiotics - minimises chance of resistance - early treatment of patient

Fig 3.2 shows the effect of increasing the concentration of the substrate (PABA) on the rate of reaction. - Curve A shows the rate of reaction without the presence of the competitive inhibitor sulfonamide. - Curve B shows the rate of reaction in the presence of the competitive inhibitor sulfonamide. Explain the effect of increasing the concentration of substrate on the rate of reaction; (i) without inhibitor, (ii) with inhibitor.

(i) - more substrate molecules enter active site - at low conc. not all active sites occupied - more ESCs can be formed - achieves Vmax - enzyme conc. limiting (ii) - inhibitor can bind to active site - occupies temporarily - fewer active sites available - more substrate reduces chance of inhibitor getting in

The apparatus shown in Fig. 16 can be used to demonstrate osmosis. When the capillary tube with visking tubing bag was placed in solution *Y*, the level of solution X inside the capillary tube rose from 10.5 mm to 26.5 mm. (i) The ruler was used to measure the distance along the capillary tube and was accurate to the nearest 0.5 mm. Calculate the percentage uncertainty of the measurement. (ii) What conclusions can be drawn about the composition of solutions X and Y?

(i) 26.5 - 10.5 = 16.0 0.5 + 0.5 = 1.0 1/10 x 100 ANSWER: 6.25% (ii) Solution Y is hypotonic (higher water potential), and therefore water moves down a water potential gradient and enters solution X by osmosis. Solution X is hypertomic (lower water potential)

Malaria is a disease that is estimated to kill around 80 people every hour worldwide. (a) The symptoms of malaria are caused by a single-celled organism belonging to the genus Plasmodium. (i) Plasmodium is described as a parasite. Define the term parasite.

- an organism which survives by getting nutrients from a host cell - lives in host - at expense of host

The Madidi National Park is also home to approximately 260,000 humans who support themselves by means of cattle-farming, and the production of timber and Brazil nuts (a large nut harvested from a local native tree). Conservationists have been working with: - local people to promote sustainable use of these resources; and - government agencies to maintain the quality of the national park. Explain why the Madidi National Park is an example of conservation rather than preservation.

- because there are local people there - sustainable use - area used for logging/farming/nut production - active measures/ work to maintain biodiversity/ habitat/ park

Tiktaalik roseae is a member of the kingdom Animalia. The structure of its individual cells has not been preserved by fossilisation. state two features of cells of an organism from the kingdom Plantae that would not be present in the cells of T. roseae.

- cell wall - chloroplast - permanent vacuole - starch granules

A group of students used the following method to investigate osmosis in plant cells. Cut pieces of plant material of equal surface area ensuring no skin is present. - Rinse to remove cell debris. - Gently pat the plant pieces dry with a paper towel. - Weigh each plant and record mass. - Put the plant piece in a 200cm3 beaker. - Cover plant piece with 50cm3 of sucrose solution. - Use sucrose solutions of 0, 0.1, 0.3, 0.5, 0.7 mol/dm3 - Leave for 24 h. - Remove the piece of plant material. - Dry carefully using a paper towel. - Weigh the plant piece and record the mass. - Calculate the percentage change in mass for each piece. - Repeat twice for each sucrose concentration. The students investigated material from three different plants: carrot, courgette and potato. Their results are shown in Table 16. (i) Explain why it was necessary to calculate percentage change in mass. (ii) The students identified replicate 3 of the potato in 0.7 mol/d,3 sucrose as anomalous. Suggest a practical error by the students that might have caused this result to be anomalous and explain the likely effect of this error. (iii) Use Table 16 to identify which plant cells contained the highest concentration of sucrose. Justify your conclusion.

(i) Each piece of plant material could have different initial masses as it ha sto be the same volume (ii) The student could have not dried the piece of potato as much as the other two so it had a smaller percentage change in mass (iii) The courgette had the highest sucrose concentration and therefore the lowest water potential, as in pure water it had the highest percentage increase in mass 0.5 and 0.7 mol/dm3 sucrose, it had to be the lowest percentage decrease in mass.

The sweet pea plant has been used to study in hesitance since the nineteenth century. The seeds of the sweet pea can vary in colour in colour and shape. The gene that controls colour has two alleles: - Y is dominant and produces yellow seeds - y is recessive and produces green seeds The gene that controls shape has two alleles - R is dominant and produces round seeds - r is recessive and produces wrinkled seeds (a) In the nineteenth century, Gregor Mendel crossed a pea plant that was heterozygous for both seed colour and shape with a pea plant that had green and wrinkled seeds. (i) List the gametes that would be produced by a sweet pea plant that was heterozygous for both seed colour and shape. (ii) List the genotypes of the offspring that were produced from Mendel's cross and state the corresponding phenotypes.

(i) YR, Yr, yR, yr (ii: genotypes: YyRr, Yyrr, yyRr, yyrr phenotypes: yellow round, yellow wrinkled, green round, green wrinkled

Antibodies are important biological molecules. (a) Describe how the structure of antibodies allows them to perform their function. (In your answer you should clearly link structure to function.)

- 2 light chains and 2 heavy chains - variable region allows binding to antigen - 2 variable regions allows binding of more than one antigen - variable region on different antibodies allows specificity to different antigens - constant region allows binding to phagocytes - hinge region allows flexibility - disulfide bridges hold polypeptides together

Most studies estimate the population density of jaguars in the South American rainforest to be 5 individuals per 100km2. In the 2007 study: - 100 camera traps were set up covering an area of 271km2. - 28 images of 9 different jaguars were recorded. How well do these results support a population estimate of 5 individuals per 100km2?

- 3 jaguars per 100km2 - lower than estimate - so does not support - low/unknown repeatability/reproducibility - some support because 3 is close enough to estimate - some individuals not photographed - if many individuals not trapped, population could be higher than estimate

(b) Shortly after the voyage, Darwin sketched a diagram in his notebook. His sketch is shown in Fig. 5.1. - A, B, C and D represent different modern day organisms. - 1) represents an ancestral organism. Explain what the sketch shows about the relationship between organisms A, B, C and D.

- B and C and D are more closely related to each other than to A - A is in different (taxonomic) group from the other 3 - B and C and D , share more , recent common ancestor - phylogeny / evolution of B and C and D diverged at same point

The specific immune response involves B and T lymphocytes. There is variation in specific immune responses between individual animals. Variation between immune responses can be influenced by genes and their environment. Using examples, explain how both genes and environment can cause animals to vary in their specific immune responses.

- CD4 receptors in T helper cells - mutations - a gene codes for a protein which is an antibody and has different primary structure, secondary structure and bonds within - there are different pathogens in the environment - animals that live in sterile conditions have a weaker immune system as they have not developed an immunological memory from B- memory cells - autoimmune responses

It is possible to manufacture antibodies to treat certain diseases. These are known as synthetic antibodies. DNL-Fab3, shown in Fig. 4.2 is an example of a synthetic antibody. State two conclusions that can be drawn from Fig. 4.2 about the differences between the way DNL-Fab3 functions and the functioning of normal antibodies.

- DNL-Fab3 can bind to 3 antigens as it has 3 variable regions whereas a normal antibody can only bind to 2 - DNL-Fab3 cannot bind to phagocytes whereas normal antibodies can

(ii) Using the information in Fig. 3.1, explain why sulfonamide acts as a competitive inhibitor of DHPS.

- able to bind to active site - similar shape to DHPS - complementary active site - both have hex ring - both have NH2 - only sulfonamide contains S

The Madidi National Park, in the South American rainforest, is home to a wide variety of species. The largest predator in the area is the jaguar. These large cats are well camouflaged and hunt mostly at night. A single individual can cover a very large area. In 2007 the Wildlife Conservation Society (WCS) attempted to estimate the population of jaguars in the Madidi National Park. - Digital camera traps were placed in areas that jaguars were likely to visit. - If an infrared beam was broken by an animal, the camera was activated. - The camera then took a photograph of the animal. Suggest why it was not appropriate to estimate the number of jaguars using the capture-recapture technique.

- estimate will be inaccurate (because of low numbers) - dangerous (for collector or jaguar)

In 2006, the scientific journal, Nature, reported the discovery of a fossil from around 380 million years ago. It was given the name Tiktaalik rosaeae. This fossil has some features in common with fish and some features in common with amphibians. A photograph of the fossil is shown in Fig. 1.1. A diagram of the fossil viewed from above is shown in Fig. 1.2. (a) (i) Suggest *one* adaptation, visible in Fig. 1.1 and 1.2, which would be an advantage for life under water.

- fins - streamlining / streamlined shape

(ii) Explain why the human body's primary defences do *not* prevent the entry of Plasmodium into the body.

- mosquito feeds on blood - bites skin

Antibiotic resistance is becoming an increasing problem. Describe how a sulfonamide-resistant population of bacteria could develop.

- mutation - sulfonamude is selective agent - resistant survive - mutation passed to offspring - happens over many generations

Drugs, such as antibiotics, are often first discovered in the natural environment. Explain why it may become increasingly difficult to discover new drugs in the future.

- new drugs come from plants - biodiversity is reducing - habitats destroyed - global warming

Fossils provide strong evidence that organisms have evolved over time. Describe *other* types of evidence that support the theory of evolution.

- similarities / differences in genes / genetics / DNA / - molecular / biochemical evidence RNA / molecules / biochemistry - similarities / differences in nucleotide / base , sequence - similarities / differences in cytochrome c / haemoglobin / ATP synthase / RNA polymerase - similarities / differences in sequence of amino acids - similarities between any of the above implies close relationship - evolution within human history - similarities in / differences in / comparison of embryology / morphology / anatomy / physiology / behaviour

The graph shows a typical population growth curve.

B (V: reproduction rate is higher than death rate W: as time doubles population more than doubles X: reproduction rate is much higher than death rate Y: population growth is slowing Z: reproduction rate is similar to death rate)

An individual's immune responses can change throughout their lifetime. Fig. 4.1 shows one person's immune response to the influenza virus when they were first infected and when they were infected two years later b6 a new mutated strain of the virus. The influenza virus has many antigens to which the immune system can respond. Fig. 4.1 shows the response to four of these antigens (A-D). Explain the differences in the person's initial immune response to the influenza virus with their immune response two years later.

B memory cells are acting against the B and D antigens in the secondary response.

Which of the following statements about ecosystems is *not* true?

B: An ecosystem is all of the organisms and habitats in a large area.

Which of the following statements about antibiotic resistance is correct?

B: Antibiotic resistance in bacteria is evidence to support Darwin's theory of evolution by natural selection.

Below are three processes that occur within living organisms. Which of these processes is important in determining the body plan of an organism?

B: Only 1 and 2 (1. apoptosis 2. mitosis)

Three methods of pathogen transmission between animals or plants are sited below.

B: Only 1 and 2 (1. direct contact 2. vectors)

(c) Erythrocytes contain haemoglobin, which is a globular protein. Blood vessel walls contain collagen, which is a fibrous protein. Describe the differences between globular and fibrous proteins using haemoglobin and collagen as examples.

GLOBULAR PROTEINS: - spherical shape - hydrophilic R groups on outside, hydrophobic R groups on inside - form H-bonds with water - soluble - e.g. enzyme, hormone, antibody, channel, carrier - left-handed helix structure - haemoglobin transports O2 - four haem groups - tertiary structure in ball shape FIBROUS PROTEIN: - no prosthetic group - collagen has high proportion of glycine, chains lie close together - crosslinks are staggered to avoid weak points - collagen forms part of tendon/cartilage/ligament/bone/connective tissue/bronchi/bronchioles/trachea/skin

Triglycerides are a type of lipid molecule that can be broken down during hydrolysis reactions. Using the structure of triglyceride molecules as an example, explain what is meant by hydrolysis.

Hydrolysis is the process in which water is used to break a chemical bond; triglycerides can be hydrolysed to produce one glycerol and three fatty acids.

Complete the passage by choosing the most appropriate word from the list.

Lipids have many roles in living organisms. Some are used for energy STORAGE in adipose cells. Unsaturated fatty acids contain at least one double bond between two CARBON atoms and so contain fewer HYDROGEN atoms. All lipids are INSOLUBLE in water so need to be transported in the blood by lipoproteins. Cholesterol molecules increase the STABILITY of membranes, and cholesterol is also used to synthesise steroid hormones and VITAMINS.

Water moves by osmosis in living organisms. (i) Define osmosis.

The net movement of water down its water potential gradient across a partially permeable membrane