9700_s09_qp_4
A paper of Biology, 9700
Questions:
10
Year:
2009
Paper:
4
Variant:
0
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1
The respiratory quotient (RQ) is used to show what substrates are being metabolised in respiration. The RQ of a substrate may be calculated using the formula below: RQ = molecules of CO2 given out molecules of O2 taken in When the unsaturated fatty acid linoleic acid is respired aerobically the equation is: C18H32O2 + 25O2 ……… CO2 + 16H2O + energy Calculate how many molecules of carbon dioxide are produced when one molecule of linoleic acid is respired aerobically. answer Calculate the RQ for linoleic acid. answer Hummingbirds feed on nectar from flowers only during daylight hours. Nectar is rich in sugars. shows a hummingbird. For Examiner’s Use Hummingbirds regulate their body temperature whereas butterflies do not regulate their body temperature. Explain briefly the effect of an increase in temperature on the rate of respiration of a butterfly.
12. Energy and respiration  →  12.1. Energy
12. Energy and respiration  →  12.2. Respiration
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2
For Examiner’s Use The steroid hormones oestrogen and progesterone are secreted by the ovary. State precisely the sites of secretion of each. oestrogen progesterone The most effective oral contraceptives for general use are the so-called combined oral contraceptives (COCs), which contain both oestrogen and progesterone. Explain how COCs produce their effects. Describe two social implications of the use of contraceptives.
15. Control and coordination  →  15.1. Control and coordination in mammals
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3
For Examiner’s Use The African elephant, Loxodonta africana, is a large herbivorous mammal which eats tree leaves. It has the longest gestation period of any land mammal and normally produces one offspring at a time. Its habitat is mainly savannah. Suggest how human activities have caused the African elephant to become endangered. The meerkat, Suricata suricatta, also lives in the savannah of southern Africa. It is a carnivorous mammal and feeds on insects, worms, snails and other invertebrates. It grows up to 30 cm in length and lives in large family groups in burrows. shows a meerkat. With reference to the information given, suggest why the meerkat is less likely than the elephant to become endangered.
18. Classification, biodiversity and conservation  →  18.3. Conservation
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For Examiner’s Use shows a section through a maize fruit. A B C D Name the parts labelled A to D. A B C D Describe the function of the endosperm. For Examiner’s Use The corn earworm, is the larva of a moth Helicoverpa zea, that is a serious pest of maize. Insecticides containing pyrethrum have long been used to control this insect. These act by irreversibly inhibiting the enzyme acetylcholinesterase, which normally catalyses the hydrolysis of acetylcholine. Describe how an insecticide could irreversibly inhibit acetycholinesterase. Suggest the effects on synapses of this irreversible inhibition of acetylcholinesterase. Some populations of H. zea have developed resistance to pyrethrum. This occurs as the result of a point mutation of the acetylcholinesterase gene. Many different such mutations have been identified in different populations. Explain how a point mutation in the acetylcholinesterase gene could confer resistance to pyrethrum. For Examiner’s Use • A group of corn earworms was collected from a field where the farmer had reported resistance to insecticides containing pyrethrum. • Another group was collected from a field where the insects showed no resistance (were susceptible). • Some individuals from these two groups were crossed with each other to form a hybrid group. Insects from each of the three groups were then exposed to a range of concentrations of pyrethrum. The percentage of the insects that were dead after 24 hours was recorded. The results are shown in Table 4.1. Table 4.1 dose of insecticide / g per group % mortality of insects after 24 hours resistant group hybrid group susceptible group 0.1 0.5 1.5 2.5 5.0 10.0 30.0 With reference to Table 4.1, compare the effect of the insecticide on the resistant group and on the hybrid group. For Examiner’s Use Assuming that resistance is conferred by a single point mutation in the gene for acetycholinesterase, suggest an explanation for the overall differences between all three groups of insects in Table 4.1.
15. Control and coordination  →  15.2. Control and coordination in plants
19. Genetic technology  →  19.3. Genetically modified organisms in agriculture
14. Homeostasis  →  14.2. Homeostasis in plants
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For Examiner’s Use The fungus Penicillium chrysogenum is grown in fermenters on an industrial scale to produce penicillin, using a batch culture system. Explain why batch culture, rather than continuous culture, is used for the production of penicillin. Temperature and pH are normally controlled in the fermenter. Temperature is kept constant, while pH is held at a value of 5.5 for the first stage of the fermentation and then raised to 6.8 and kept constant for the remainder of the fermentation period. shows how the pH and the concentration of penicillin in the culture change over time, when the pH is controlled and when the pH is not controlled. time / hours pH penicillin concentration / arbitrary units Key pH controlled pH not controlled Key pH controlled pH not controlled For Examiner’s Use With reference to , describe and explain the differences in the concentration of penicillin in the culture when the pH is controlled and when the pH is not controlled. Explain why penicillin affects bacteria but not viruses.
10. Infectious diseases  →  10.2. Antibiotics
3. Enzymes  →  3.2. Factors that affect enzyme action
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For Examiner’s Use Describe the role of insulin in the regulation of blood glucose concentration. State two advantages of treating diabetes with insulin produced by gene technology. One of the steps in the production of bacteria capable of producing human insulin is the insertion of the gene coding for human insulin into a plasmid vector. shows one of the artificial plasmids constructed to act as a vector. ampicillin resistance gene DNA of plasmid tetracycline resistance gene target site for the restriction enzyme BamHI G G A T C C C C T A G G For Examiner’s Use With reference to , explain the importance of the plasmid having a single target site for a particular restriction enzyme, such as BamHI. The genes for ampicillin resistance and tetracycline resistance on the plasmid allow the genetic engineer to distinguish between bacteria that have taken up different circles of DNA. Complete the table to show whether bacteria which have taken up each different circle of DNA are, or are not resistant to ampicillin, to tetracycline or to both. Show presence of resistance with a tick (✓) and absence of resistance with a cross (✗). circle of DNA taken up by bacteria bacteria resistant to ampicillin bacteria resistant to tetracycline unaltered plasmids recombinant plasmids that have taken up the wanted gene circles of the wanted gene Explain why genes for antibiotic resistance are now rarely used as markers in gene technology. Describe the use of one alternative marker gene that can be used instead of an antibiotic gene.
19. Genetic technology  →  19.1. Principles of genetic technology
19. Genetic technology  →  19.2. Genetic technology applied to medicine
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For Examiner’s Use The inheritance of coat colour in horses is complex but all horses have one of two base colours, red or black. The base colour is controlled in a simple monohybrid way. • When chestnut stallions and mares are mated the foals are always chestnut. • When black stallions are mated with black mares, either black or chestnut foals may be produced. Draw a genetic diagram to show how two parents with black coat colour can produce a chestnut foal and the probability of such an event occurring. Choose a letter symbol to represent coat colour. For Examiner’s Use Five other genes can modify the base coat colour. One of these genes is the C gene. There are two alleles of this gene, C and CCR. • C does not affect the base coat colour. • CCR may modify the base coat colour. • If a chestnut horse has at least one CCR allele its phenotype will be palomino, which is a light cream colour. • If a black horse has at least one CCR allele its effect will not be noticeable in the phenotype. Complete the genetic diagram below. parental genotype aaCCCR AaCC parental phenotype …………………… …………………… gametes …………… …………… …………… …………… offspring genotypes …………… …………… …………… …………… offspring phenotypes …………… …………… …………… ……………
16. Inheritance  →  16.2. The roles of genes in determining the phenotype
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For Examiner’s Use shows a scanning electron micrograph of a section through a leaf of the Christmas rose, Helleborus niger. M { } N Name M and N. M N Gases leave and enter the leaf through pores called stomata. Describe and explain how a stoma is opened. For Examiner’s Use outlines the main reactions in the light-dependent stage of photosynthesis. increasing energy level light reduced NADP photosystem II light photosystem I H2O R S 2e– 2e– 2e– Name the process shown by the dotted arrows ( ). Describe what happens to water at R. State the product formed as electrons flow along S. Explain briefly the role of reduced NADP in the light-independent stage.
13. Photosynthesis  →  13.1. Photosynthesis as an energy transfer process
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