State what is meant by the term carbon sink.
Explain how the restoration of damaged peatlands (rewetting) reduces the concentration of carbon dioxide (CO2\text{CO}_2CO2) in the atmosphere, and describe the impact of this on global temperatures.
The release of pollutant gases into the atmosphere has various harmful effects on the environment and human health. Complete the table below by finding the missing gases or effects (i) to (v).
| Gas | Source | Environmental/Biological Effect |
|---|---|---|
| (i) | High-temperature combustion in vehicle engines | Contributes to photochemical smog and acid rain |
| Sulfur dioxide | Combustion of coal in power stations | (ii) |
| (iii) | Anaerobic decay in landfills and livestock farming | Greenhouse gas contributing to global warming |
| Tropospheric ozone | Reaction of vehicle emissions with sunlight | (iv) |
| (v) | Old refrigerants and air conditioning units | Catalyses the destruction of stratospheric ozone |
44 exam-style questions on Edexcel IGCSE Biology Human influences on the environment. Each one has a worked solution and a mark scheme showing where the marks go.