# Phloem tissue transports sugars around a plant. Explain how the structure of phloem tissue is suited to its function of transporting sugars from leaves to other parts of the plant.

> Pearson Edexcel A-Level Biology A (9BI0) — 2.4 Plant structure and function · Explain · 5 marks

> Phloem is a specialised plant tissue found throughout the plant body. It transports dissolved sugars, produced during photosynthesis in the leaves, to areas such as roots and growing shoots where the sugars are needed for respiration and growth.

## Mark scheme (5 marks)

1. Phloem transports sugars (dissolved food / assimilates) from the leaves (source) to other parts of the plant such as roots or growing regions (sink)
2. Phloem sieve tube elements have sieve plates / pores at the end walls, which allow sugars to flow through between cells
3. Sieve tube elements have reduced / no nucleus and few organelles, leaving more space for the flow of sugars
4. Companion cells have many mitochondria to provide energy (ATP) to actively load sugars into the phloem / maintain the sieve tube elements
5. Phloem forms a continuous network / tubes throughout the plant, allowing sugars to reach all parts including roots and growing shoot tips

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/phloem-tissue-transports-sugars-around-a-1750f53d) · Published by Druglandscape Ltd.