Biology 9700 · AS & A Level · Respiration

Respiration — practice question

The respiratory quotient (RQ) is used to show which substrate is being broken down in respiration.
(a(i))[1]

Define the term respiratory quotient by stating the relationship between carbon dioxide release and oxygen uptake in respiration.

(a(ii))[1]

For aerobic respiration of the unsaturated fatty acid linoleic acid, the equation is: $\mathrm{C_{18}H_{32}O_2} + \dots \, \mathrm{O_2} \rightarrow 18\mathrm{CO_2} + 16\mathrm{H_2O} + \text{energy}$. Calculate how many molecules of oxygen are used when one molecule of linoleic acid is respired aerobically.

(a(iii))[1]

Calculate the RQ of linoleic acid.

(b)[4]

Describe the results in Fig. 10.2 and suggest reasons for them.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: the ratio of $CO_2$ given off to $O_2$ taken in

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