Biology 0610 · IGCSE · Photosynthesis

Photosynthesis — practice question

The rate of photosynthesis in terrestrial plants can be found by measuring how much carbon dioxide is absorbed.
(a)[2]

Explain why plants absorb carbon dioxide during photosynthesis.

(b)[2]

Explain how the readings from the apparatus can be used to calculate the rate of photosynthesis.

(c(i))[1]

State one environmental factor that should have been kept unchanged in this investigation.

(c(ii))[3]

Describe how temperature affects the rate of photosynthesis when carbon dioxide concentration A was used. Support your answer with data from Fig. 2.2.

(c(iii))[2]

Calculate the percentage increase in the rate of photosynthesis at $30\,^{\circ}\text{C}$ when the carbon dioxide concentration was raised from A to B as shown in Fig. 2.2. Show your working and give your answer to the nearest whole number.

(c(iv))[3]

Explain the effect of increasing temperature on the rate of photosynthesis for carbon dioxide concentration B. Use the term limiting factor in your answer.

(c(v))[1]

The student concluded that carbon dioxide concentration is the factor limiting the rate of photosynthesis between $30\,^{\circ}\text{C}$ and $35\,^{\circ}\text{C}$ from the results shown for A in Fig. 2.2. State the evidence for this conclusion.

(d)[2]

Predict and explain what would happen to the rate of photosynthesis if the investigation is continued at temperatures above $45\,^{\circ}\text{C}$.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: carbon dioxide acts as a raw material / substrate / reactant

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