Potassium Pump In Plants

Question 1

Describe what happens when the stoma is closed

Answer 1

• K+ ions have the same concentration in guard cells and epidermal cells
• Light activates K+ pumps which actively transport K+ from the epidermal cells into the guard cells
• K+ pump uses ATP produced during respiration
• Increased concentration of K+ in guard cells
• Lowers the water potential in guard cells
• water movies in by osmosis down water potential gradient
• stoma open
• malte (formed from starch) is formed which is an anion to re-equillibriate the conditions in guard cells