1. The drawing shows a 24-hour cycle for the opening and closing of stomata from the same plant.
(a)  Explain how this opening and closing of stomata is adventageous to the plant.




  The diagram shows the potassium (K+) ion concentrations in the cells around an open and closed stoma in Commelina. The concentrations are in arbitrary units.

(b) Explain how the movement of K+ ions accounts for the opening of the stoma.







(c) Explain how K+ ions are moved against a concentration gradient.






NEAB 1998