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Date May 2010 Marks available 1 Reference code 10M.3.SL.TZ1.11
Level Standard level Paper Paper 3 Time zone Time zone 1
Command term Label Question number 11 Adapted from N/A

Question

The diagram below shows part of the respiratory pathway. The number of carbon atoms in each molecule is indicated.

Label pyruvate and acetyl coenzyme A on the diagram above.

[1]
a (i).

Indicate two places where decarboxylation occurs on the diagram.

[1]
a (ii).

List one product other than carbon dioxide formed in this stage of respiration.

[1]
a (iii).

State precisely where in a cell this stage of respiration is occurring.

[1]
b.

Markscheme

(i) and (ii)

a (i).

(i) and (ii)

a (ii).

NADH + H+ /FADH2 /ATP (or GTP)

a (iii).

matrix of mitochondrion

b.

Examiners report

The majority were able to gain three marks from the parts of this question.

a (i).

The majority were able to gain three marks from the parts of this question.

a (ii).

The majority were able to gain three marks from the parts of this question.

a (iii).

As the question asked, candidates need to be precise in their answers, and many simply gave “mitochondria“ as their answer instead of specifying “matrix”.

b.

Syllabus sections

Additional higher level » Topic 8: Metabolism, cell respiration and photosynthesis » 8.2 Cell respiration
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