A large enclosed crop-growing chamber contains crop plants in soil beds and open irrigation channels. Sunlight enters through a transparent roof. During the day, water enters the chamber air. At night, the roof is cooled and liquid water collects on its inner surface before running into a storage tank.
Describe how water from the irrigation channels ends up as liquid droplets on the inner surface of the roof.
A grower removes half of the leaves from the crop plants but keeps all other conditions the same.
Explain how this change would affect the mass of water vapour entering the chamber air from the crop plants.
Before any leaves were removed, the following masses of water were measured during one day.
| Measurement | Mass of water in kg |
|---|---|
| water entering the air from the open irrigation channels | 18 |
| water entering the air from the moist soil | 6 |
| water entering the air from the crop plants | 24 |
| water collected from the roof | 42 |
Calculate the percentage of the water that entered the chamber air during this day that was collected from the roof.
Tests were carried out on the collected water.
| Test | Result for collected water | Maximum permitted in potable water |
|---|---|---|
| number of harmful microorganisms in 100 cm³ | 3 | 0 |
| concentration of dissolved substances in mg dm⁻³ | 310 | 500 |
Explain whether the collected water is potable. Use both test results in your answer.
101 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.