# Explain how the structural adaptations of a xerophyte leaf reduce water loss by transpiration.

> IB DP Biology Higher Level (2023 syllabus) — B4.1 Adaptation to environment · Explain · 4 marks

## Mark scheme (4 marks)

1. Thick/waxy cuticle reduces evaporation of water from the epidermal surface
2. Stomata sunken in pits/crypts or located on the lower (abaxial) surface, which traps humid air and reduces the water potential gradient between leaf and atmosphere
3. Rolled/folded leaves (e.g. Marram grass) enclose stomata, creating a humid microenvironment that reduces the water potential gradient driving transpiration
4. Dense covering of leaf hairs (trichomes) on the leaf surface reduces air movement/wind speed over stomata, maintaining a thicker boundary layer and reducing transpiration

## Key terms

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

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](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/explain-how-the-structural-adaptations-of-5cf3abaf) · Published by Druglandscape Ltd.