Biology 5090 · O Level · Aerobic respiration

Aerobic respiration — practice question

Respiration, which releases energy from food in living organisms, can be represented by the equation below: glucose + oxygen → carbon dioxide + water A student investigated the rate at which oxygen was taken in for respiration by some small animals. The apparatus shown in Fig. 1.1 was used. The apparatus was sealed by closing the clip so that any change in the volume of gases in the test-tube and capillary tube caused the coloured liquid drop to move. The speed at which the coloured liquid drop moves is linked to the rate of oxygen uptake by the small animals. When the small animals in the test-tube respire, they take in oxygen and give out carbon dioxide.
(a(i))[1]

Describe what happens to the carbon dioxide they produce.

(a(ii))[2]

Explain why the coloured liquid drop moves along the capillary tube towards the small animals.

(b(i))[2]

Complete Table 1.1 by entering these readings.

(b(ii))[4]

Construct a graph of the data in the completed Table 1.1 on the grid below. Join your plotted points with ruled, straight lines.

(b(iii))[3]

Use your graph to estimate the position of the drop at 25 minutes. Show your working on the graph. position of drop at 25 minutes [BLANK]

(c(i))[1]

Calculate the distance moved by the drop during the investigation. [BLANK] cm

(c(ii))[2]

Calculate the rate of movement of the drop during the investigation in cm per minute. Show your working. rate of movement of drop [BLANK] cm per minute

(d(i))[2]

Suggest why the student should repeat this investigation several times.

(d(ii))[1]

Suggest a control experiment for this investigation.

Worked solution & mark scheme

This 18-mark question has a full step-by-step worked solution and mark scheme. One marking point: “taken up by the chemical” …

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