CIE A Level Biology (9700) 2019-2021

Revision Notes

7.2.1 Water Movement in Plants

Water Movement in Plants

  • Water is transported through a plant, from its point of absorption (the root hairs of the roots) up the xylem tissue in the stem, to the leaves of the plant, where water vapour evaporates through a process called transpiration (evaporation of water vapour from the stem and leaves)
  • This is a passive process, as the movement of water is being driven by the evaporation of water vapour occurring from the leaves
  • Roughly 99% of the water absorbed is lost to transpiration
  • There is a gradient in water potential (Ψp) between the root hair cell (high water potential) and the leaves (low water potential), that plants rely on to move water up the plant
  • Water also moves between cells from a high water potential to low water potential

Investigating water movement in plants using a stain, IGCSE & GCSE Biology revision notes

An overview of the movement of water through a plant, from a high water potential in the roots to a low water potential in the leaves

Exam Tip

Remember that pure water has a water potential of 0, so the more negative the water potential is the lower its water potential is.

Author: Catherine

Cate has over 20 years’ experience teaching Biology to IGCSE, IB and A-level students in seven different countries across Asia, Europe, North America and the Middle East. This has given her a fine appreciation of different cultures, places and teaching methods. Cate has a keen interest in producing Biology revision resources that will help students engage with the subject.

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