Plant Transpiration
Transpiration through stomata pulls water up the xylem
Closing of stomata: reduces water loss but also reduces CO2 supply
Stomata close and open through turgor pressure in guard cells:
- water loss ? guard cells relax (become weaker) ? stoma closes
- water uptake ? turgor increases ? stoma opens
Turgor control by active uptake of K+ ions into guard cells; higher ion (K+) concentration pulls water into cell (osmosis!); ion uptake requires energy, control by plant hormone
Diel cycle: open during morning, close in the evening