Biology 9700 · AS & A Level · Protein synthesis

Protein synthesis — practice question

Fig. 1.1 shows an electron micrograph of part of a eukaryotic cell.
(a)[1]

State how it is possible to deduce that Fig. 1.1 is a transmission electron micrograph and not a scanning electron micrograph.

(b)[2]

Both the Golgi body and the rough endoplasmic reticulum form part of the cell’s internal membrane network. Outline structural features shown in Fig. 1.1 that identify G as the Golgi body rather than the rough endoplasmic reticulum.

(c)[2]

Calculate the actual diameter, X-Y, of the mitochondrion labelled in Fig. 1.1. State the formula that you will use for your calculation. Give your answer to the nearest whole nanometre (nm).

(d(i))[3]

Outline the fluid mosaic model of membrane structure. A diagram may be placed in the space below.

(d(ii))[1]

The inner and outer membranes of the mitochondrion are different in the detail of their membrane components. The inner membrane is also much less permeable than the outer membrane. Suggest one way in which the structure of the inner membrane may differ from that of the outer membrane to produce a less permeable inner membrane.

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