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

Photosynthesis as an energy transfer process — practice question

Fig. 1.1 displays a transmission electron micrograph of a chloroplast.
(a)[2]

In Fig. 1.1, add label lines and letters to identify: A - the place where the carbohydrate product of photosynthesis is stored B - the location of the light independent stage.

(b(i))[1]

State the name of the structure labelled C in Fig. 1.1.

(b(ii))[4]

Explain the connection between the structure of C and its function.

(c(i))[2]

C4 plants possess anatomical adaptations that help maintain a high photosynthetic rate at elevated temperatures. C3 plants lack these adaptations, and at high temperatures an extra reaction occurs that lowers the rate of photosynthesis. Explain why this high-temperature reaction in C3 plants reduces the rate of photosynthesis.

(c(ii))[3]

C4 plants achieve higher photosynthetic rates than C3 plants when the atmospheric oxygen to atmospheric carbon dioxide ratio is high. Fig. 1.2 shows how atmospheric carbon dioxide concentration has changed over the last 50 million years. Evidence suggests that C4 plants first appeared 30 million years ago. Using Fig. 1.2, suggest why C4 plants first appeared 30 million years ago.

(ii)[3]

Using Fig. 1.2, suggest why C4 plants first appeared 30 million years ago.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: A: label line to starch grain

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