Transpiration

Question 1

How is the xylem formed

Answer 1

Plant cells line up vertically then the cell wall disintegrate so the the plant cells die and from tube with lignin spirals

Question 2

Define guard cells

Answer 2

Control the size of the stomata, and their opening and closing

Question 3

Define Transportation

Answer 3

Water from the cells lining the air spaces evaporating into water vapour, and diffusing out of the stomata

Question 4

What can affect the rate of transpiration

Answer 4

What affects the rate of evaporation is what’s going to affect the rate of transpiration

Question 5

Why is it important that the stomata is closed at some times ?

Answer 5

It is important that plants can close their stomata so that they can limit the loss of water (vapour)

Question 6

What are the factors that affect the rate of transpiration?

Answer 6

1) Temperature
2) Light Intensity
3) Humidity
4) Air Movement

Question 7

How does Temperature affect the rate of transpiration ?

Answer 7

Higher temp = more evaporation.

Question 8

How does Light Intensity affect the rate of transpiration ?

Answer 8

higher = more photosynthesis –> more CO2 required –> stomata open –> water loss

Question 9

How does Humidity affect the rate of transpiration ?

Answer 9

Higher = less transpiration because less steep concentration gradient –> lower rate of diffusion

Question 10

How does Air Movement affect the rate of transpiration ?

Answer 10

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

Question 11

What is the function of the waxy cuticle ?

Answer 11

Waxy cuticle –> prevents water loss, barrier against pathogens

Question 12

What happens to the plant once the water loss is greater than the intake ?

Answer 12

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

Question 13

What does a Potometer show ?

Answer 13

Potometer shows uptake of water by a plant in different directions

Question 14

What causes the uptake of water to occur ?

Answer 14

Almost all of the uptake of water is due to water lost by transpiration

Question 15

A small amount is due to what ?

Answer 15

A small amount is due to metabolism like photosynthesis

Question 16

What does the phloem do ?

Answer 16

Phloem transports food (dissolved sugars) to storage organs where it provides an energy store for the winters

Question 17

Define Translocation

Answer 17

Movement of dissolved sugars from the leaves where they are created to the rest of the plant

Question 18

How do Aphids play a part in Translocation ?

Answer 18

Aphids feed on the phloem and suck out the sugary fluid