# Explain why the properties of water make it well suited to its role as a transport medium in living organisms.

> AQA A-Level Biology (7402) — 3.1.7 Water · Explain · 5 marks

> Water is the main component of blood plasma, phloem sap, and many other transport fluids found in organisms.

## Mark scheme (5 marks)

1. Water is a good solvent / many substances dissolve in water
2. This allows dissolved substances (e.g. glucose, mineral ions, hormones) to be carried / transported in solution
3. Water molecules are cohesive / water molecules stick together / water has high cohesion
4. Cohesion allows water to form a continuous column / allows water to be pulled up through xylem vessels
5. Water has a relatively high heat capacity / resists changes in temperature, so temperature of transport fluid remains stable / enzymes in the fluid are not denatured

## Key terms

- [transport medium](https://www.gradenine.co.uk/glossary/transport-medium)

## Related

- [Revision notes for AQA A-Level Biology (7402)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-properties-of-water-8c600f4a) · Published by Druglandscape Ltd.