Uptake of Water by Root Hair Cells (WJEC GCSE Biology)

Revision Note

Naomi Holyoak

Last updated

Importance of Water to Plants

  • Water is essential to plant survival for several reasons:

    • Photosynthesis

      • Water is a reactant in photosynthesis

    • Mineral transport

      • Minerals dissolve in water, allowing them to be easily transported when water moves from the roots to the leaves

    • Support

      • Plants that have a high water content will have turgid cells; this causes the cell vacuoles to exert outward pressure on the plant cell walls and provides essential structural support for non-woody parts of plants

      • When water availability is low plant cells can become flaccid, causing plants to wilt

Root Hair Cells & Absorption

  • Root hairs are extensions of the cells that form the outer layer of plant roots

    • These cells are known as root hair cells

  • Every root will have many root hairs, greatly increasing the root surface area available for absorption of water from the soil

  • Water enters the root hair cells by osmosis

    • Water moves into root hair cells down a water concentration gradient because there is a higher concentration of water in the soil than there is inside the root hair cells

Root hair cell diagram

root hair cell structure

Root hair cells have a large surface area, increasing the absorption of water by osmosis

Active Transport by Root Hair Cells

Higher Tier Only

  • Mineral salts, e.g. nitrates, are usually taken up by root hair cells by the process of active transport

    • This is because mineral salts are usually present at lower concentrations in the soil than inside root hair cells, so they need to be transported against their concentration gradient

  • Active transport requires energy, meaning that root hair cells must be actively respiring to release the energy needed

    • Root hair cells contain many mitochondria; the site of aerobic respiration

You've read 0 of your 5 free revision notes this week

Sign up now. It’s free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Naomi Holyoak

Author: Naomi Holyoak

Expertise: Biology

Naomi graduated from the University of Oxford with a degree in Biological Sciences. She has 8 years of classroom experience teaching Key Stage 3 up to A-Level biology, and is currently a tutor and A-Level examiner. Naomi especially enjoys creating resources that enable students to build a solid understanding of subject content, while also connecting their knowledge with biology’s exciting, real-world applications.