Absorption of Water by Root Hair Cells (Edexcel IGCSE Biology)

Root Hair Cells

Spec point — 2.55B · understand how water is absorbed by root hair cells

Uptake of water into the root

• Root hair cells are tiny, single-celled extensions of epidermis cells in the root

• Root hair cells are adapted for the efficient uptake of water (by osmosis) and mineral ions (by active transport)

  • Root hairs increase the surface area of plant roots, increasing the rate at which water and minerals can be taken up
  • They contain mitochondria which release energy for active transport

A root hair cell

The structure of a root specifically allows it to maximise absorption of water by osmosis and mineral ions by active transport

The route of water through the plant

• Water moves by osmosis into the root hair cells, then through the root cortex and finally into the xylem vessels

  • Remember waters move from a solution with a high water potential to a solution with a low water potential
  • Water potential is a measure of how freely water molecules can move

• Once the water gets into the xylem, it is carried up to the leaves where it enters mesophyll cells

• A summary of the pathway is:

root hair cell → root cortex cells → xylem → leaf mesophyll cells

Pathway of water into and across a root