# A student drinks a large volume of water on a hot day. Explain how the kidney responds to restore normal water balance in the body.

> Eduqas A-Level Biology — 4.5 Homeostasis and the kidney · Explain · 5 marks

> After drinking 1.5 litres of water quickly, the water concentration of the student's blood rises above the normal level.

## Mark scheme (5 marks)

1. The hypothalamus detects the increase in blood water concentration
2. Less ADH is released / secreted by the pituitary gland
3. The kidney tubules become less permeable to water
4. Less water is reabsorbed back into the blood / more water remains in the tubules
5. A larger volume of dilute urine is produced, restoring normal blood water concentration

## Related

- [Revision notes for Eduqas A-Level Biology](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-drinks-a-large-volume-26751039) · Published by Druglandscape Ltd.