A small group of green salt-marsh plants has a total leaf area of 0.75 m2.
A sensor measures the change in carbon dioxide in the air per square metre of leaf during one 24-hour period.
| Conditions | Duration in hours | Carbon dioxide change per m2\text{m}^2m2 of leaf per hour |
|---|---|---|
| Bright light | 6 | 4.0 mg removed |
| Low light | 8 | 1.0 mg removed |
| Darkness | 10 | 0.8 mg released |
The values measured in the light are net rates. The rate of respiration per square metre of leaf is constant throughout the 24-hour period.
Calculate the total mass of carbon dioxide used in photosynthesis during the 24-hour period.
Calculate the net change in the mass of carbon dioxide in the air during the 24-hour period. State whether the mass increases or decreases.
83 exam-style questions on AQA GCSE Biology 7.2 Organisation of an ecosystem, covering 7.2.1 Levels of organisation, 7.2.2 How materials are cycled, 7.2.3 Decomposition, and 7.2.4 Impact of environmental change (HT only). Each one has a worked solution and a mark scheme showing where the marks go.