Transpiration And Stomata

Question 1

What are the factors affecting the rate of transpiration?

Answer 1

• Light Intensity
• Temperature
• Air Flow ( Wind )
• Humidity

Question 2

How does light intensity affect the rate of transpiration?

Answer 2

The greater the light intensity, the greater the rate of photosynthesis.
So, the stomata will open to allow more CO2 to enter.
At the same time, water vapour will diffuse out of the leaf.

At night, the rate of transpiration decreases.
The stomata close as photosynthesis doesn’t take place in the dark.
So, less water will evaporate.

Question 3

How does temperature affect the rate of transpiration?

Answer 3

The greater the temperature, the higher the rate of transpiration.
This is because the water particles will have more energy to evaporate and diffuse out of the stomata.

Question 4

How does air flow affect the rate of transpiration?

Answer 4

The better the air flow ( strong wind ) , the greater the rate of transpiration.
This is because the wind will remove any water vapour outside the leaf, allowing more water to evaporate.
So, the water diffuses from an area of high concentration inside the leaf to low concentration outside the leaf.

Question 5

How does humidity affect the rate of transpiration?

Answer 5

The drier the conditions, the greater the rate of photosynthesis.
This is due to the high concentration gradient between the water inside the leaf and outside of it.

Question 6

What is the name of the cells that control the opening and closing of stomata?

Answer 6

Guard cells.

Question 7

What happens to the guard cells when the plant has lots of water?

Answer 7

The guard cells become turgid and open the stomata.
So, gases can be exchanged for photosynthesis.

Question 8

What happens to the guard cells when the plant has a lack of water?

Answer 8

The guard cells become flaccid and close the stomata.
So, water loss is reduced.