# Explain how the carbon cycle helps to maintain a balance of carbon dioxide in the atmosphere, and suggest how human activity has disrupted this balance.

> OCR GCSE Chemistry A: Gateway Science (J248) — C6.3 Interpreting and interacting with Earth systems · Explain · 4 marks

> Scientists monitor the concentration of carbon dioxide in the atmosphere. Over the last two centuries, concentrations have risen significantly, and this rise closely follows the increase in industrialisation worldwide.

## Mark scheme (4 marks)

1. The carbon cycle removes carbon dioxide from the atmosphere through photosynthesis (by plants/algae/phytoplankton)
2. Carbon dioxide is returned to the atmosphere through respiration and/or decomposition of organisms
3. Burning/combustion of fossil fuels releases additional carbon dioxide into the atmosphere
4. This additional carbon dioxide cannot be fully removed by the natural cycle, so the concentration of carbon dioxide in the atmosphere increases, contributing to climate change

## Key terms

- [carbon cycle](https://www.gradenine.co.uk/glossary/carbon-cycle)

## Related

- [Revision notes for OCR GCSE Chemistry A: Gateway Science (J248)](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/explain-how-the-carbon-cycle-helps-f669b354) · Published by Druglandscape Ltd.