B2: TRANSLOCATION + TRANSPIRATION

Question 1

What is translocation?

Answer 1

the transport of dissolved sugars around a plant via the phloem

Question 2

What is transpiration?

Answer 2

transport of water from the roots to their leaves to evaporate out of the stomata via xylem vessels

Question 3

Factors affecting rate of transpiration

Answer 3

-light intensity
-temp
-air flow
-humidity

Question 4

How does light intensity affect rate of transpiration?

Answer 4

-the brighter the light, the higher the transpiration rate
-stomata begin to close as it gets darker (photosynthesis cant happen without light so the stomata don’t need to be open to let CO2 in) if the stomata aren’t open very little water can escape

Question 5

How does temp affect rate of transpiration?

Answer 5

-the higher the temp, the faster the rate of transpiration
-high temp gives the water particles more energy to evaporate and diffuse out of the stomata

Question 6

How does air flow affect rate of transpiration?

Answer 6

-the better the air flow, the greater the transpiration rate
-if air flow around a leaf is poor then there is a high conc. of water around the leaf as well as inside the leaf so diffusion won’t happen as quickly

Question 7

How does humidity affect rate of transpiration?

Answer 7

-the more humidity, the lower the rate of transpiration
-if the air is humid then there is a high conc. of water around the leaf as well as inside the leaf so diffusion won’t happen as quickly

Question 8

How can you estimate the rate of transpiration?

Answer 8

measuring water uptake of a plant using a potometer

Question 9

How can you measure water uptake of a plant using a potometer?

Answer 9

-set up potometer
-record starting position of air bubble
-start a stopwatch and record distance moved by bubble per unit time
-keep conditions constant throughout experiment

Question 10

Name the type of cell that open and close stomata

Answer 10

guard cellsH

Question 11

Adaptations of guard cells

Answer 11

-when plant has a high conc. of water guard cells become turgid which makes stomata open so gas exchange can occur for photosynthesis
-when plant has a low conc. of water guard cells become flaccid making the stomata close which prevents too much water vapour escaping
-thin outer walls and thickened inner walls
-sensitive to light (close at night)
-found on underside of leaf (cooler so less water lost)