# Phloem and xylem are the two main transport tissues in plants. Explain how the structure of phloem is adapted for the transport of sugars through a plant.

> WJEC A-Level Biology (Wales) — 2.3 Adaptations for transport in plants and animals · Explain · 5 marks

> Plants produce sugars by photosynthesis in their leaves. These sugars must be transported to other parts of the plant, such as the roots and growing regions, where they are needed for respiration and growth.

## Mark scheme (5 marks)

1. Phloem is made of living cells / sieve tubes are living cells
2. Sieve tubes have no nuclei, allowing more space for sugar solution to flow through
3. Sieve tubes are connected via their cytoplasms / sieve plates allow sugar solution to pass between cells
4. Companion cells provide energy (ATP) for the active loading of sugars into the phloem
5. Sugars are transported from source (leaves where photosynthesis occurs) to sink (roots / growing regions) — this is called translocation

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](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/phloem-and-xylem-are-the-two-cd595aa2) · Published by Druglandscape Ltd.