# Acid rain is formed when sulfur dioxide and nitrogen oxides are released into the atmosphere. Explain how acid rain affects living organisms and ecosystems.

> Eduqas A-Level Biology — 3.6 Human impact on the environment · Explain · 5 marks

> Power stations burning fossil fuels and vehicle exhausts are major sources of sulfur dioxide and nitrogen oxides. These gases dissolve in water droplets in clouds, forming acids that fall as acid rain, sometimes hundreds of kilometres from the original source.

## Mark scheme (5 marks)

1. Acid rain lowers the pH of lakes and rivers / makes water more acidic
2. Low pH kills aquatic organisms / fish and invertebrates cannot survive in acidic water
3. Acid rain damages or kills trees / vegetation by damaging leaves or roots
4. Acid rain leaches / washes away minerals/nutrients from soil, reducing soil fertility
5. Loss of one species affects others in the food chain / food web, reducing biodiversity

## Key terms

- [acid rain](https://www.gradenine.co.uk/glossary/acid-rain)
- [pH](https://www.gradenine.co.uk/glossary/ph)

## 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)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/acid-rain-is-formed-when-sulfur-9997dfbe) · Published by Druglandscape Ltd.