The kidneys play a crucial role in maintaining the body's water balance. The table below shows the daily water intake and output measurements for two hospitalized patients, Patient X and Patient Y.
| Volume of water (ml\text{ml}ml) | ||
|---|---|---|
| Water Source / Route | Patient X | Patient Y |
| Water taken in from food and drinks | 2400 | 2400 |
| Water produced during aerobic respiration | 300 | 300 |
| Total Input | 2700 | 2700 |
| Water lost from kidneys as urine | 2100 | 1400 |
| Water lost through skin, lungs, and feces | 1100 | 1100 |
| Total Output | ? | ? |
Calculate the total water output (in ml\text{ml}ml) for both Patient X and Patient Y.
Identify which patient needs medical intervention due to an excessive loss of water from their body. Explain your choice using evidence from the water balance data.
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.