stomata & guard cells Flashcards
what shape do guard cells have?
a kidney shape
what diffuses in through the stomata?
carbon dioxide
what diffuses out through the stomata?
oxygen and water vapour
what is the function of the guard cell?
control the opening and closing of the stomata
describe what happens to the guard cells when the plant if full of water, and short of water?
full: When the plant has lots of water, the guard cells fill with it and go plump and turgid. This makes the stomata open so gases can be exchanged for photosynthesis.
short: When the plant is short of water, the guard cells lose water and become flaccid, making the stomata close. This helps stop too much water escaping.
how are the guard cells adapted to opening and closing constantly?
They have thin outer walls and thick inner walls. They are also sensitive to light and close at night.
why do guard cells close at night?
To save water, and reduce transpiration rates. They close at night because they don’t lose out on photosynthesis as it rarely takes place at night, as the light intensity is a limiting factor.
why do you find more stomata on the undersides of leaves?
The lower surface is shaded and cooler so less water is lost through the stomata than if they were on the upper surface.
what are guard cells adapted for?
gas exchange and controlling water levels
what would happen to the plant if there were no guard cells or the plant was not watered?
It would wilt, as it would dry out. This is because it would lose water faster than it being replaced, leading to an extreme lack of water.
in what conditions do guard cells become plump with water?
bright light
how are stomata adapted for their function?
-allow control of gaseous exchange and water loss from the leaf
-more stomata on base of leaf to minimise water loss as this side is cooler and shaded
-have guard cells which control their opening and closing
what is the function of the stomata?
to control water loss, for gas exchange
