The table below shows the daily water gained and lost by a healthy adult under normal conditions:
| Water gained | Volume (litres) | Water lost | Volume (litres) |
|---|---|---|---|
| Fluids consumed | 2.5 | Breathing and sweating | 1.4 |
| Water in food | 0.8 | In faeces | 0.2 |
| Metabolic water | 0.3 | In urine | □\square□ |
Assuming that the total volume of water gained equals the total volume of water lost, calculate the volume of urine produced by this person.
On a hot day, this person's water loss through sweating increases significantly. Explain how the kidneys maintain water balance under these conditions, and state the effect on the concentration and volume of urine produced.
22 exam-style questions on OCR GCSE Biology 3.3 Maintaining internal environments, covering 3.3.1 Importance of a constant internal environment, 3.3.2 The skin and body temperature, 3.3.3 Insulin and blood sugar, 3.3.4 Glucagon and blood sugar, 3.3.5 Type 1 and type 2 diabetes, 3.3.6 Osmotic changes in body fluids, 3.3.7 Kidneys and water balance, 3.3.8 Structure of the kidney and tubule, 3.3.9 ADH and kidney tubule permeability, and 3.3.10 Responses to temperature and osmotic challenges. Each one has a worked solution and a mark scheme showing where the marks go.