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

Photosynthesis as an energy transfer process — practice question

Corals are found in shallow seawater. They are made up of colonies of tiny animals known as polyps. Inside the cells of these polyps are photosynthetic protoctists called algae, and this arrangement benefits both the coral polyps and the algae. The algae that live inside the cells of the polyps are also able to survive independently as free-living algae.
(a)[2]

Suggest and explain how being inside the cells of coral polyps increases the rate of photosynthesis in these algae compared with free-living algae.

(b)

The relative abundance of five different chloroplast pigments in the algae of corals was measured. The results are given in Table 2.1.

(b(ii))[4]

Outline the method you would use to separate and identify the pigments contained in an extract of these algae.

(c)[3]

Table 2.2 shows the light wavelengths at which each algal chloroplast pigment has its two highest peaks of light absorption. Corals kept in tanks are often lit by lamps that radiate mainly violet and blue light with wavelengths in the range of $400$-$490\ \text{nm}$. With reference to Table 2.1 and Table 2.2, suggest why lamps radiating mostly violet and blue light are expected to increase coral growth.

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