Describe, with the aid of a diagram, the structure of the cell membrane, (40% marks) and transmembrane transport processes. (60% marks)
The structure of the cell membrane was generally well covered by most candidates. Many
had difficulties structuring an answer for the transmembrane transport processes. Dividing
this section into proteins (some receptors, channels etc.) and carbohydrates (some receptors,
immune reactions etc) followed by a very brief discussion of each type of process would have
aided candidates towards providing a good answer.
A decent diagrammatic representation of the cell membrane which is hastily scrawled during the primary exam would probably look a bit like this:
Though it is difficult to reconstruct the expectations of the examiners from their laconic comments ("generally well covered by most candidates" is all we get), one can - from looking at textbooks - assume that the basic elements you need to include would be:
As for the membrane transport...
In pictureless written format, the transport of molecules into (and out of) the cell can be said to take three main forms:
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