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

Photosynthesis as an energy transfer process — practice question

Corals live in shallow seawater. They are formed from colonies of tiny animals called polyps. These polyps contain photosynthetic protoctists, called algae, inside their cells, which benefits both the coral polyps and the algae. The algae living inside the polyps’ cells can also survive independently as free-living algae.
(a)[2]

The photosynthesis rate of algae living inside coral polyp cells is greater than that of free-living algae. Suggest and explain how living inside coral polyp cells increases the rate of photosynthesis in these algae compared with free-living algae.

(b)

The relative amounts of five different chloroplast pigments in the algae of corals were measured. The results are shown in Table 2.1.

(c)[3]

Table 2.2 gives the light wavelengths at which each algal chloroplast pigment has its two greatest absorption peaks. Corals kept in tanks are often lit by lamps that emit 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 emitting mainly violet and blue light are expected to boost coral growth.

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