OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What advantage do air spaces provide within leaves?

1. They store water

2. They allow easier movement of gases

3. They absorb nutrients

4. They enhance photosynthesis

The correct answer is: They allow easier movement of gases

Air spaces within leaves play a crucial role in facilitating gas exchange, which is essential for the process of photosynthesis and respiration in plants. The presence of these air spaces increases the surface area available for gases, such as carbon dioxide and oxygen, to move in and out of the leaf more efficiently. This is particularly important during the day when photosynthesis occurs, as it allows carbon dioxide to diffuse into the leaf where it's needed and oxygen, a byproduct of photosynthesis, to diffuse out. The structure of leaves is designed to maximize the exchange of gases with the surrounding environment, and the air spaces help to ensure that all parts of the leaf receive adequate amounts of these gases. This efficient gas exchange is vital for the overall health and productivity of the plant and directly supports the plant's ability to produce energy through photosynthesis.