Question

1. if the guard cells closed the stomata, what molecules would be unable to enter the leaf? what molecules would be unable to leave the leaf? 4. what would happen to the rate of photosynthesis if the stomata were closed? 5. under what conditions would a plant close the stomata? 6. what does the statement “structure fits function” mean? provide an example to illustrate your answer. 7. what is the main function of leaves?

Explanation:

1. Stomata are pores for gas - exchange. When closed, carbon dioxide ($CO_2$) can't enter and oxygen ($O_2$) and water vapor can't leave.
2. Photosynthesis requires $CO_2$ which enters through stomata. So, the rate of photosynthesis would decrease as $CO_2$ supply is limited.
3. Plants close stomata in hot, dry conditions to prevent water loss, or in the dark when photosynthesis isn't occurring.
4. "Structure fits function" means that the form of a biological structure is related to its purpose. For example, the flat and broad shape of a leaf maximizes light - absorption for photosynthesis.
5. The main function of leaves is photosynthesis, converting light energy into chemical energy.

Answer:

1. Molecules unable to enter: Carbon dioxide. Molecules unable to leave: Oxygen and water vapor.
2. The rate of photosynthesis would decrease.
3. In hot, dry conditions to prevent water loss or in the dark when photosynthesis isn't occurring.
4. It means the form of a biological structure is related to its purpose. Example: The flat and broad shape of a leaf maximizes light - absorption for photosynthesis.
5. Photosynthesis.