Leaf adaptations Questions

Question 1

Explain why the stomata are usually open in the day time and closed at night.

Answer 1

In the day time the stomata are open to allow carbon dioxide into the leaf for photosynthesis. At night the stomata are usually closed because photosynthesis does not occur unless there is light available. Closing the stomata reduces water loss.

Question 2

Explain why most leaves are a thin, flat shape.

Answer 2

• large surface area to absorb light for photosynthesis
• large lower surface of leaf for gas exchange
• thin for short diffusion pathway for gas exchange

Question 3

The leaf is adpated for photosynthesis, but these adaptations mean the leaf can lose water.
Explain how.

Answer 3

• large surface area from which water can evaporate

- stomata open for gas exchange which allows water to evaporate

Question 4

Some plants living in hot, dry places have stomata that open and close in the daytime.
These plants store CO2 at night to be used in the day time. Suggest why their stomata open only at night.

Answer 4

• hotter in day/cooler at night

- this reduces water loss