Biology 9700 · AS & A Level · Respiration

Respiration — practice question

The molecules named below are all connected 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 tree sap sample, which was rich in sugars, was found to be contaminated with yeast. The ethanol concentration in this sample was measured at regular intervals. The results are shown 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

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