Advanced Placement (AP) Biology Practice Exam

Which of the following components is crucial for the regulation of gas exchange in plants?

1. Chlorophyll

2. Stomata

3. Xylem

4. Phloem

The correct answer is: Stomata

The regulation of gas exchange in plants is primarily facilitated by stomata, which are small openings typically located on the underside of leaves. Stomata allow for the exchange of gases, such as carbon dioxide entering the plant for photosynthesis and oxygen exiting as a byproduct. Additionally, stomata also help in regulating water loss through transpiration. While chlorophyll is vital for capturing light energy during photosynthesis, it does not play a direct role in gas exchange. Xylem is responsible for the transport of water and minerals from the roots to other parts of the plant, and phloem is responsible for the transport of organic nutrients. However, neither xylem nor phloem is involved in the regulation of gases that plants exchange with their environment. Therefore, stomata are the crucial components specifically designed to manage gas exchange effectively.