A Level Biology Practice Exam

What is primarily exchanged through the stomata during photosynthesis?

1. Water vapor and nutrients

2. Carbon dioxide and oxygen

3. Nitrogen and phosphorus

4. Oxygen and hydrogen

The correct answer is: Carbon dioxide and oxygen

During photosynthesis, the primary gases exchanged through the stomata are carbon dioxide and oxygen. Stomata are small openings on the surfaces of leaves that facilitate gas exchange. Carbon dioxide enters the leaf through these openings, allowing the plant to use it in the process of photosynthesis, which produces glucose and releases oxygen as a byproduct. Consequently, oxygen is released back into the atmosphere through the stomata as a result of this process. The role of stomata in regulating the exchange of these gases is critical for a plant's ability to photosynthesize efficiently. Leaf tissues are designed to minimize water loss while maximizing the intake of carbon dioxide, which is essential for producing the energy-rich compounds that sustain plant growth.