Transpiration
Biology: Cambridge International GCSE Supplement, topic 8.3.1
Transpiration
Transpiration is the evaporation of water vapour from the leaves of plants. This is what drives water to be drawn up from the roots, up the stem, to the leaves.
Root hair cells
- Root hair cells absorb water from the soil via osmosis (movement of water from a dilute solution to a more concentrated solution).
- Mineral ions are taken up by active transport (movement of ions and molecules across a cell membrane to an area of higher concentration).
Xylem
- After being absorbed by the root hair cells, the water and minerals are transported in xylem vessels.
- Water molecules in the xylem stick together by cohesion, drawing water up the stem.
Leaves
- Once it reaches the leaves, most of the water evaporates from the surfaces of leaf mesophyll cells into the air spaces between cells.
- This water vapour then diffuses out of the stomata (pores in leaves).
Test yourself on Transpiration
By what process are mineral ions taken up by plants?
What is the technical term for the evaporation of water vapour from plant leaves?
Absorption in root hair cells