Transpiration

Question 1

What is transpiration?

Answer 1

• Brings water into the leaf.
• Water is required for photosynthesis.
• Transports dissolved minerals.
• Evaporation of water from the leaf , cools the leaf down.

Question 2

Where does transpiration start?

Answer 2

• Evaporation of water from cells inside of the leaf.
• Water vapour diffuses from the air spaces of spongy mesophlly and out of the leaf through the stomata.
• Water passes from the xylem into the leaf, to replace the water that has been lost.
• Water is drawn into root hair cells and up xylem vessels up to the leaf.

Question 3

What happens to the rate of transpiration if temperature is high?

Answer 3

• Evaporation is faster when temperature is high.
• Also Faster under dryer conditions when air is not humid.
• ## Evaporation takes place much faster in dryer conditions.

Question 4

What happens to rate of transpiration in windy conditions?

Answer 4

• Increases.
• Wind removes water vapour.
• ## Allowing more water to evaporate.

Question 5

When light increases what happens to rate of transpiration?

Answer 5

• Increases.
• High light intensity increases rate of photosynthesis.
• Stomata open to allow co2 to enter.
• Once stomata has opened water vapour can pass out of the leaf.

Question 6

How do stomata work?

Answer 6

• Stomata are surrounded by 2 gaurd cells.
• Light intensity is high= guard cells swell and change shape.
• Causes them to open.
• Co2 can diffuse into the leaf and be used in photosynthesis.
• Under hot conditions: plant closes it’s stomata to reduce water lost by transpiration but the plant cannot photosynthesise.