# Explain why the removal of a ring of bark and phloem from around the trunk of a tree eventually leads to the death of the roots, but does not immediately kill the leaves.

> OCR A-Level Biology A (H420) — 3.3 Transport in plants · Explain · 4 marks

> A technique called ring-barking (girdling) involves cutting away a complete ring of bark and phloem tissue from around the circumference of a tree trunk, leaving the xylem intact. Foresters have observed that ring-barked trees continue to produce new leaves for several weeks after the procedure, but eventually die as the roots deteriorate first.

## Mark scheme (4 marks)

1. Phloem is the tissue responsible for transporting sucrose/organic solutes from leaves to roots
2. Without a supply of sucrose/organic solutes, root cells cannot respire/grow and eventually die
3. Xylem is left intact so water and mineral ions continue to be transported from roots to leaves in the short term
4. Leaves do not die immediately because they are the source of photosynthate and have existing stores, but will eventually die once roots deteriorate and can no longer supply water via xylem

## Key terms

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

## 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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-removal-of-a-50c67060) · Published by Druglandscape Ltd.