Edexcel IGCSE Biology 2.41B gas exchange in plants

Practise comparing respiration and photosynthesis using CO2/O2 exchange, light intensity data and colour changes in indicator experiments.

Exam points

explain tube results where organisms change CO2 concentration in light or dark
compare photosynthesis and respiration rates from light intensity or indicator evidence

[Maximum number: 2]

The diagram shows parts of the human respiratory system with some structures labelled.

Figure for Question 2.41B Gas exchange in respiration and photosynthesis question 1 — Edexcel IGCSE Biology

A scientist compared the rate at which oxygen is used during exercise by a person who is a non-smoker with a person who is a smoker.

The rate is measured in $\mathrm{cm}^{3}$ per minute for each kilogram of body mass.
The table shows the scientist's results.

Table for Question 2.41B Gas exchange in respiration and photosynthesis question 1 — Edexcel IGCSE Biology

Calculate the volume of oxygen used in 30 minutes by a non-smoker with a mass of 70 kg .
volume =…… $\mathrm{cm}^{3}$

$35 \times 70 \times 30=73500\left(\mathrm{~cm}^{3}\right)$

One mark for $\times 35$ or $\times 70$ or $\times 30$ or 2450 or 1050 or 2100

Accept 74000 or 73000 for two marks

Correct answer gains both marks

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2.41B Gas exchange in respiration and photosynthesis question 1