Biology 9700 · AS & A Level · Photosynthesis as an energy transfer process

Photosynthesis as an energy transfer process — practice question

Scientists have devised a method of making food by means of artificial photosynthesis. - Solar panels change sunlight energy into electrical energy. - That electricity drives an electrolysis reaction between carbon dioxide gas and water, producing the organic product acetate. - The single-celled alga Chlamydomonas, which is a protoctist, is able to use acetate for growth and reproduction in the dark, rather than photosynthesising in the light. - The algae can then be processed to produce a food product. Fig. 4.1 presents an outline of the artificial photosynthesis process.
(a)[3]

Identify three features that the artificial photosynthesis process shown in Fig. 4.1 has in common with the normal process of photosynthesis.

(b)[2]

Fig. 4.2 shows the single-celled alga Chlamydomonas. It has a large, cup-shaped chloroplast for photosynthesis. Structures A and B in Fig. 4.2 lie inside the chloroplast. Name structures A and B.

(c(i))[1]

Thylakoid membranes are where the light-dependent stage of photosynthesis takes place. Name the products formed in the light-dependent stage of photosynthesis.

(c(ii))[4]

Some proteins in the thylakoid membrane are involved in the light-dependent stage of photosynthesis. Explain the functions of the different proteins that act during the light-dependent stage of photosynthesis.

(d)[1]

The products of the light-dependent stage of photosynthesis are used in the Calvin cycle. Calvin cycle intermediates are used to make amino acids, carbohydrates and lipids. Name the Calvin cycle intermediate that can be used to produce starch.

(e)[3]

Scientists claim that the artificial photosynthesis process shown in Fig. 4.1 is more efficient at turning light energy into food than normal photosynthesis by crop plants. Give reasons why this claim may or may not be true.

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