Transpiration Flashcards
How is the xylem formed
Plant cells line up vertically then the cell wall disintegrate so the the plant cells die and from tube with lignin spirals
Define guard cells
Control the size of the stomata, and their opening and closing
Define Transportation
Water from the cells lining the air spaces evaporating into water vapour, and diffusing out of the stomata
What can affect the rate of transpiration
What affects the rate of evaporation is what’s going to affect the rate of transpiration
Why is it important that the stomata is closed at some times ?
It is important that plants can close their stomata so that they can limit the loss of water (vapour)
What are the factors that affect the rate of transpiration?
1) Temperature
2) Light Intensity
3) Humidity
4) Air Movement
How does Temperature affect the rate of transpiration ?
Higher temp = more evaporation.
How does Light Intensity affect the rate of transpiration ?
higher = more photosynthesis –> more CO2 required –> stomata open –> water loss
How does Humidity affect the rate of transpiration ?
Higher = less transpiration because less steep concentration gradient –> lower rate of diffusion
How does Air Movement affect the rate of transpiration ?
Windy = more transpiration as wind takes water vapour around the leaf away and so maintains a steep concentration gradient for water to diffuse out at a higher rate
What is the function of the waxy cuticle ?
Waxy cuticle –> prevents water loss, barrier against pathogens
What happens to the plant once the water loss is greater than the intake ?
If water loss is greater than intake:
1. wilting –> prevents further water loss –> reduced SA for water loss for evaporation
2. Stomata close –> stops photosynthesis and risks overheating but stops water loss and further wilting
What does a Potometer show ?
Potometer shows uptake of water by a plant in different directions
What causes the uptake of water to occur ?
Almost all of the uptake of water is due to water lost by transpiration
A small amount is due to what ?
A small amount is due to metabolism like photosynthesis
What does the phloem do ?
Phloem transports food (dissolved sugars) to storage organs where it provides an energy store for the winters
Define Translocation
Movement of dissolved sugars from the leaves where they are created to the rest of the plant
How do Aphids play a part in Translocation ?
Aphids feed on the phloem and suck out the sugary fluid
