9700_w07_qp_4
A paper of Biology, 9700
Questions:
11
Year:
2007
Paper:
4
Variant:
0
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1
shows two unicellular organisms, P and R. These organisms are members of different kingdoms. X 20 000 P R X 2 000 Calculate the actual sizes, in µm, of P and R, as shown by the lines on . Show your working. P µm R µm Examiner’s Use Identify the kingdom to which each organism belongs. Write your answers in the table below. Complete the table by listing five features which distinguish P from R. One has been completed for you. unicell P unicell R kingdom features cell wall present cell wall absent
18. Classification, biodiversity and conservation  →  18.1. Classification
1. Cell structure  →  1.2. Cells as the basic units of living organisms
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2
Use shows part of a tropical rainforest. Tropical rainforests have a high biodiversity. tall tree forming upper canopy epiphytes growing on a tall tree liana climbing tall tree buttresses at base of trunk to support tree young tree growing to fill a gap Explain what is meant by biodiversity. Examiner’s Use Suggest why tropical rainforests have a high biodiversity of animal species. Discuss why it is important to maintain biodiversity.
18. Classification, biodiversity and conservation  →  18.2. Biodiversity
18. Classification, biodiversity and conservation  →  18.3. Conservation
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3
Use Outline the symptoms of cystic fibrosis (CF). CF is caused by a recessive mutation, b, on an autosome. Draw a genetic diagram to show, for parents with genotypes BbXX and BbXY, the probability of having a daughter who suffers from CF. In your genetic diagram, show the genotypes of the gametes and the genotypes and phenotypes of the offspring. genetic diagram parental genotypes BbXX x BbXY genotypes of gametes genotypes and phenotypes of offspring Examiner’s Use One of the many mutations for CF results in the amino acid arginine being replaced by histidine in the polypeptide encoded by the CF gene. Explain how a mutation may cause such a change in the amino acid sequence of a polypeptide. A genetic test was performed on two individuals, D and E, to find the base sequences of a small part of the CF gene. The different base sequences are shown diagramatically in . Individual E has CF. G T A individual D bases bases C G T A individual E C With reference to , state, how the base sequence of E differs from that of D Examiner’s Use the effect of this difference in the polypeptide produced by the two individuals.
16. Inheritance  →  16.2. The roles of genes in determining the phenotype
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5
Use Wheat, maize and sorghum are three of the most important cereal crops in the world. shows the effect of temperature on the rate of photosynthesis of wheat plants. CO2 used per dm2 of leaf per hour / mg temperature / °C With reference to , describe the effect of temperature on the rate of photosynthesis of wheat plants. Suggest why temperature affects the rate of photosynthesis in the way you have described in . Examiner’s Use The conditions in which young plants of wheat and maize are grown affects their ability to photosynthesise at high and low temperatures when they are mature. Young maize and wheat plants were grown to maturity at high and low temperatures. When they were mature, their rate of photosynthesis was measured at different temperatures. The results are shown in . CO2 used per dm2 of leaf per hour / mg maize grown at high temperature wheat grown at low temperature wheat grown at high temperature maize grown at low temperature temperature / °C Examiner’s Use With reference to , compare the effect of temperature on the rate of photosynthesis of maize plants and wheat plants that were grown at a high temperature when they were young. Maize is a C4 plant. Explain how the structure of the leaves of maize plants enables them to photosynthesise more effectively at high temperatures than wheat plants. Low temperatures slow down the formation of the membranes inside chloroplasts in maize leaves, but not in wheat leaves. Use this information to explain the differences between the results for maize and wheat grown at low temperatures, shown in . Examiner’s Use Cereal crops frequently form the staple diet of human populations. Table 5.1 shows the oil and starch content of maize and sorghum grains. Table 5.1 percentage of dry mass maize sorghum oil 4.7 3.8 starch 62.2 70.1 Name the part of the maize grain in which oil and starch are stored. With reference to Table 5.1, compare the energy values of maize and sorghum grains when the oil and starch they contain are used as respiratory substrates.
13. Photosynthesis  →  13.2. Investigation of limiting factors
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6
Use Couples who are unable to conceive naturally may be able to have fertility treatment involving in-vitro fertilisation (IVF). Outline the technique of IVF. Table 6.1 shows the success rate, in terms of live births, for IVF using eggs from women of different ages. Table 6.1 age of woman percentage success rate of IVF under 35 27.6 35 to 37 22.3 38 to 39 18.3 40 to 42 10.0 above 42 less than 5.0 Suggest reasons for the trend shown in Table 6.1. Examiner’s Use The cost of one IVF treatment is about US$ 5000. In some countries, in-vitro fertilisation is offered free of charge to couples who have not conceived within two years of trying. With reference to Table 6.1, put forward an argument against the public funding of in-vitro fertilisation to all couples who request it.
18. Classification, biodiversity and conservation  →  18.3. Conservation
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7
Use In aerobic respiration, the Krebs cycle is regarded as a series of small steps. One of these steps is the conversion of succinate to fumarate by an enzyme, succinate dehydrogenase. State the role played by dehydrogenase enzymes in the Krebs cycle and explain briefly the importance of this role in the production of ATP. An investigation was carried out on the effect of different concentrations of aluminium ions on the activity of succinate dehydrogenase. The enzyme concentration and all other conditions were kept constant. Fig 7.1 shows the results of this investigation. rate of fumarate production / mmol min-1 concentration of aluminium ions / µmol Examiner’s Use With reference to , describe the effect of the concentration of aluminium ions on the rate of production of fumarate suggest an explanation for this effect.
12. Energy and respiration  →  12.2. Respiration
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8
Use shows the changes in potential difference (p.d.) across the membrane of a neurone over a period of time. The membrane was stimulated at time A and time B with stimuli of different intensities. -40 potential difference across membrane of a neurone /mV +40 time / ms stimulus A stimulus B +60 +20 -20 -60 -80 threshold C D E Stimulus B resulted in an action potential. Describe what is occurring at C, D and E. C D E Examiner’s Use Suggest why stimulus A did not result in an action potential being produced whereas stimulus B did.
15. Control and coordination  →  15.1. Control and coordination in mammals
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9
Use Sickle cell anaemia is a genetic disorder that is caused by the presence of two recessive alleles. It is common amongst people of African origin. Malaria is a major cause of death in sub-Saharan Africa where 90% of the world’s cases occur. shows the distribution of sickle cell anaemia and malaria in Africa. sickle cell anaemia malaria Explain why malaria is found in the areas shown but not in areas such as northern Europe and South Africa. Examiner’s Use With reference to , explain the relationship between the distribution of sickle cell anaemia and malaria.
16. Inheritance  →  16.2. The roles of genes in determining the phenotype
10. Infectious diseases  →  10.1. Infectious diseases
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