Biology 9700 · AS & A Level · Respiration

Respiration — practice question

All living organisms carry out respiration. The ATP formed during respiration acts as the cell’s energy currency.
(a(i))[2]

Outline two examples of cell movement that require ATP.

(a(ii))[2]

ATP cannot be kept in cells so it must be continuously re-synthesised to satisfy the needs of an organism. A person with a total quantity of $0.2$ moles of ATP has to hydrolyse $150$ moles of ATP per day. Calculate how many times the total quantity of $0.2$ moles of ATP must be re-synthesised per hour to meet the demand of $150$ moles per day. Show your working and give your answer to the nearest whole number.

(a(iii))[2]

State the stages in which chemiosmosis occurs in respiration and in photosynthesis.

(b(i))[3]

Using Fig. 2.1, describe and explain how thermogenin affects ATP synthesis.

(b(ii))[3]

When the external temperature is warm, thermogenin cannot function. When the external temperature becomes cold, thermogenin is able to function as a result of cell signalling: • adrenaline is released • adrenaline acts on brown adipose cells • a sequence of events is triggered that leads to activation of the enzyme lipase • lipase hydrolyses triglycerides in the cells into fatty acids • fatty acids enter the mitochondrion • thermogenin starts to function Outline the stages of cell signalling that trigger thermogenin to function.

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