12.2. Respiration
A subsection of Biology, 9700, through 12. Energy and respiration
Listing 10 of 158 questions
shows part of the process of respiration in a mitochondrion. ETC A D C B NAD reduced NAD Krebs cycle water ATP ADP + Pi e– e– H+ H+ H+ H+ With reference to , name: area A process B substance C State the type of chemical compound that is represented by D. State the process by which ATP can be synthesised directly during glycolysis or the Krebs cycle. The elephant seal, Mirounga angustirostris, spends most of its life in the ocean. is an elephant seal. Elephant seals can stay underwater for up to two hours. During this time, respiration continues. shows the mass of blood in the body, as a percentage of total body mass, for the elephant seal and for three other mammals. elephant seal mass of blood as a percentage of total body mass dog mammal human cow shows that elephant seals have a higher mass of blood as a percentage of total body mass than humans. Calculate how many times greater this figure is for elephant seals compared to humans. Show your working and write your answer to two decimal places. answer Suggest why an elephant seal needs such a large mass of blood as a percentage of total body mass. Elephant seals have a very thick layer of adipose tissue under their skin. Adipose cells are rich in fat molecules. Suggest why 1 g of fat will produce more ATP than 1 g of carbohydrate as a respiratory substrate in aerobic respiration. Adipose tissue plays an important role in thermoregulation in elephant seals. State the role of adipose tissue in thermoregulation. The hypothalamus in the brain is the control centre for thermoregulation. Outline how a change in temperature of the external environment results in an impulse arriving at the hypothalamus. When the blood temperature of a mammal decreases, one response is that its body secretes more adrenaline. Suggest how an increase in adrenaline results in an increase in blood temperature.
9700_s20_qp_43
THEORY
2020
Paper 4, Variant 3
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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.
9700_w07_qp_4
THEORY
2007
Paper 4, Variant 0
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Questions Discovered
158