Question

Complete the sentence by choosing the correct option.

When stomata are open ...

• A. both water vapour and carbon dioxide move in and out through the stomata.
• B. only carbon dioxide moves in and out through the stomata.
• C. only water vapour moves in and out through the stomata.
• D. only oxygen moves in and out through the stomata.

Answer 1

The correct option is A

both water vapour and carbon dioxide move in and out through the stomata.

Remember that stomata are responsible for the exchange of water vapour, carbon dioxide and oxygen. So when a plant opens its stomata to take in carbon dioxide, it also loses water by transpiration and removes the oxygen produced by photosynthesis. This happens whether the plant wants it or not. What do you think a cactus does with its stomata to reduce water loss?