# Explain why the resolution of a transmission electron microscope is greater than that of a light microscope, and explain how this difference in resolution has contributed to our understanding of cell ultrastructure.

> OCR A-Level Biology A (H420) — 2.1 Cell structure · Explain · 4 marks

> Scientists studying cell organelles must choose appropriate microscopy techniques depending on the level of detail required. A transmission electron microscope (TEM) can resolve structures separated by as little as 0.1 nm, whereas a light microscope has a resolution limit of approximately 200 nm.

## Mark scheme (4 marks)

1. Resolution is limited by the wavelength of the radiation used, and electrons have a much shorter wavelength than visible light.
2. A shorter wavelength means closer objects can be distinguished as separate, giving greater resolving power.
3. The greater resolution of the TEM has allowed subcellular structures / organelles that are too small to be seen with a light microscope to be visualised.
4. This has led to a more detailed understanding of organelle function / the fluid-mosaic model of membranes / the relationship between structure and function at the ultrastructural level.

## Key terms

- [resolution](https://www.gradenine.co.uk/glossary/resolution)
- [transmission electron microscope](https://www.gradenine.co.uk/glossary/transmission-electron-microscope)
- [ultrastructure](https://www.gradenine.co.uk/glossary/ultrastructure)

## Related

- [Revision notes for OCR A-Level Biology A (H420)](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-resolution-of-a-b56c4467) · Published by Druglandscape Ltd.