Biology 9700 · AS & A Level · Respiration

Respiration — practice question

The molecules named here are all linked with respiration: ATP synthase, glucose, ATP, NAD, oxaloacetate, pyruvate, citrate, oxygen.
(a)[4]

Using these molecules, identify: - a phosphorylated nucleotide - a 3-carbon compound - a coenzyme - an enzyme

(b)

A sugar-rich sample of tree sap was discovered to be contaminated by yeast. The ethanol concentration in this sample was then measured at regular time intervals. The outcomes are displayed in Fig. 1.1.

(b(i))[2]

Calculate the percentage increase in ethanol concentration from 15 to 45 hours. Show your working.

(b(ii))[1]

Suggest why the ethanol concentration fell after 45 hours.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: ATP (adenosine triphosphate)

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