Other than acting as catalysts state three functions of proteins, giving an example of each.

The diagram shows chemiosmosis in the mitochondrion. Label I, II and III.

structural – collagen / membrane proteins;

transport – hemoglobin / protein channels;

movement – actin / myosin;

hormones – insulin / vasopressin / growth hormone;

defense – antibodies / immunoglobins;

Award any other valid function and example.

I.     ATPsynthase; (accept ATPsynthetase)

II.     \({{\text{H}}^ + }\) / protons;

III.     \({{\text{O}}_{\text{2}}}\)/oxygen;

This was an easy question on proteins with most candidates getting full marks for both (i) and (ii)

This question was very discriminating as only a few got this correct; it appeared that candidates either scored all 3 marks for correctly labelling what was happening in chemiosmosis, or none. There were some comments on the G2 forms that this diagram was a little unclear. It was felt that this was a very clear diagram, however, it was a bit tricky to decide what substances the arrows were referring to. The use of the word ‘molecules’ in the stem seemed to have confused some as label II was for protons \({\text{(}}{{\text{H}}^ + }{\text{)}}\).