MODULE 5
RESPIRATION QUESTIONS
1. The diagram shows anaerobic respiration in yeast.
(a) Complete the boxes in the diagram to show:
(i) the number of carbon atoms in each molecule of fructose bisphosphate and in each molecule of pyruvate;
(1)
(ii) the name of compound X.
(1)
(b) Under anaerobic conditions, the oxidised form of NAD is regenerated. Explain why this is essential.
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(1)
(c) In the reactions shown in the diagram, what is the net gain of ATP molecules per molecule of glucose? Explain how you worked out your answer.
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(2)
(Total 5 marks)
2 The diagram shows the main steps in the biochemical pathways involved in respiration.
(a) (i) Which step or steps take place on the cristae of the mitochondria?
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(1)
(ii) In which step or steps is carbon dioxide produced in an animal cell?
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(1)
(b) If a pond freezes over during the winter, goldfish can remain alive in the water under the ice. Explain why they use the carbohydrate stores in their bodies much faster in these conditions.
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(2)
(c) What is the main difference between the way in which ATP is produced by oxidative phosphorylation and the way in which it is produced in photosynthesis?
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(1)
(Total 5 marks)
3. A preparation of mitochondria was made from liver tissue. Substances were added to this preparation and the amount of oxygen in the preparation was monitored over a period of time. The diagram shows the trace obtained and the times when the different substances were added.
(a) Suggest why the respiratory substrate added to this preparation was a molecule from Krebs cycle and not glucose.
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(1)
(b) What additional substance, other than those mentioned on the diagram, would need to be added to this preparation in order to get the results shown?
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(1)
(c) Explain:
(i) why the amount of oxygen fell between lines A and B;
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(2)
(ii) the shape of the trace after time C.
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(1)
(Total 5 marks)
4 Cockroaches are insects. The table shows the rates of oxygen consumption and carbon dioxide production of cockroaches kept under different conditions.
Time after last fed/hours / Temperature/°C / Rate of oxygen consumption/cm3 g–1 hour–1 / Rate of carbon dioxide production/
cm3 g–1 hour–1
1 / 20 / 2.82 / 2.82
72 / 20 / 2.82 / 1.97
1 / 30 / 5.12 / 5.12
72 / 30 / 5.12 / 3.57
(a) When the temperature is raised from 20°C to 30°C, the cockroach becomes more active and its respiration rate and oxygen consumption increase. What causes the increase in respiration rate?
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(1)
(b) (i) Calculate the Respiratory Quotient (RQ) of a cockroach kept at a temperature of 20°C, 72 hours after it had last been fed. Show your working.
Respiratory Quotient =......
(2)
(ii) The rate of carbon dioxide production by cockroaches is less 72 hours after they were last fed than it is 1 hour after they were last fed. Explain why.
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(2)
(Total 5 marks)
5. (a) Complete the table with a tick if the statement is true about the particular stage of respiration.
(4)
(b) The graph shows the volume of oxygen consumed and the volume of carbon dioxide released by a small animal over a 15-minute period.
Showing your working in each case, use the graph to calculate:
(i) the rate of oxygen consumption;
Rate of oxygen consumption =...... (1)
(ii) the respiratory quotient (RQ) of this animal over the 15-minute period.
RQ = ...... (2)
(Total 7 marks)