# A star begins its life as a nebula. Describe the sequence of stages in the life cycle of a star similar in mass to our Sun, starting from the nebula stage and ending with its final state.

> WJEC GCSE Physics (Wales) — 2.1 Light, lenses and the universe · Describe · 4 marks

## Mark scheme (4 marks)

1. A nebula is a cloud of gas and dust that is pulled together by gravity to form a protostar
2. The protostar becomes a main sequence star where hydrogen nuclei fuse to form helium (nuclear fusion), releasing energy
3. When hydrogen runs out the star expands into a red giant
4. The red giant sheds its outer layers to leave behind a white dwarf as the final state

## Key terms

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

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-star-begins-its-life-as-338f4e7f) · Published by Druglandscape Ltd.