A student investigated the effect of temperature on the decay of grass cuttings.
She put 500 g of grass cuttings into each of five compost bins. She kept each bin at a different temperature.
She measured the mass of the grass cuttings in each bin after 20 days.
The Table shows her results.
Table
| Temperature in ∘C^{\circ}\text{C}∘C | Mass of grass cuttings at the start in g\text{g}g | Mass of grass cuttings after 20 days in g\text{g}g |
|---|---|---|
| 10 | 500 | 470 |
| 20 | 500 | 420 |
| 30 | 500 | 340 |
| 40 | 500 | 300 |
| 50 | 500 | 380 |
Calculate the rate of decay of the grass cuttings at 30 ∘C30\ ^{\circ}\text{C}30 ∘C.
Give your answer in g\text{g}g per day.
Describe the effect of temperature on the decay of the grass cuttings.
Explain why less mass was lost at 50 ∘C50\ ^{\circ}\text{C}50 ∘C than at 40 ∘C40\ ^{\circ}\text{C}40 ∘C.
Gardeners often turn the material in a compost heap with a fork.
Explain how this increases the rate of decay.
44 exam-style questions on Edexcel GCSE Biology 9.3 Material cycles and decomposition, covering 9.3.1 Cycling of materials through ecosystems, 9.3.2 The carbon cycle, 9.3.3 The water cycle, 9.3.4 The nitrogen cycle, 9.3.5 Indicator species and pollution, 9.3.6 Decomposition in preservation and composting, and 9.3.7 Rate changes in decay of biological material. Each one has a worked solution and a mark scheme showing where the marks go.