A level biology

Hi, I'm doing about plant responses at the moment and just was stuck on one aspect of it. Leaf loss happens to conserve water through transpiration as there is water stress and less light for photosynthesis. But surely if there is less light for photosynthesis and less water, the rate of photosynthesis/respiration and so transpiration is slowed anyway. I don't get why the stomata has to close if the rate is going to be slower anyway.

Reply 1

Saeed23

By closing their stomata, plants reduce the amount of water lost through transpiration, conserving what little water is available. it is a necessary response for the plant to conserve water and protect itself from damage in times of water stress.

(edited 1 year ago)

Reply 2

Zarek

You’re mixing up leaf loss and stoma closure. Leaf loss in deciduous plants is about hunkering down for winter where colder temperatures less light reduce ability to grow and frozen leaves would be a liability. Conversely stoma operate control water loss in hot dry times. Sure the lack of air getting in to the leaf will slow photosynthesis, but it manages water stress. My biology teacher waxed lyrical about stoma, having a water filled plastic tube to demonstrate how they work