Transport of water, and gas exchange in plants. Flashcards
what type of leaf do we need to look at at A-level?
dictyledonous leaf.
Describe the structure of a dicotyledonous leaf.
Look on page 47 in goodnotes 5.
Describe gas exhange in plants.
Gas exchange takes place, VIA the stomata.
describe gas exhange in plants during the day and during the night.
Ga exchange takes place, VIA the stomata.
during the day, the stomata are open.
-Both photosynthesis and respiration occur.
during the night the stomata are closed.
- only respiration takes place.
state and explain the 3 features that ensure efficient gas exhange in plants.
- numerous stomata.
- large surface are of mesophyll cells.
- air spaces facillitate diffusion.
state what is meant by transpiration.
transpiration is the evaporation of water , through the stomata, down a water potential gradient.
what are the 4 factors by which transpiration is increased?
- Light.
- increasing temperature.
- wind
- humidity.
explain how light affects transpiration.
increasing light, increass the number of stomata, and thus the rate of evaporation.
explain how temperature affects transpiration.
Increasing temperature, will will increase the kinetic energy of water molecules, and thus, the rate of evaporation.
explain how wind affects transpiration.
it decreases water vapour outide of the leaf, thus increasing the water potential gradient.
explain how humidity, affects transpiration.
decreasing humidity outside the leaf, will increase the water potential.
state all the features that a xerophytic plant has, in order to minimise water loss.
hairs, rolled leafs, stomata in pits, closed stomata, thixk waxy cuticle
explain how hairs, rolled leafs, and stomata in pits, help reduce the rate of transpiration.
They allow the leaf to trap water vapour in the outside of the air, thus decreasing the water potential gradient
explain how having a thick waxy cutile, helps reducing the rate of water loss.
it increases the diffusion distance , and thus reduces the rate of evaporation.
