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

What is the main purpose of leaves in a plant?

1. To provide structural support

2. To absorb carbon dioxide

3. To absorb sunlight for photosynthesis

4. To attract pollinators

The correct answer is: To absorb sunlight for photosynthesis

The primary function of leaves in a plant is to absorb sunlight for the process of photosynthesis. During photosynthesis, leaves capture light energy and convert it into chemical energy, allowing the plant to produce glucose, which serves as food, and oxygen, which is released into the atmosphere. The structure of leaves, characterized by their broad and flat shape, maximizes surface area to efficiently capture sunlight. Additionally, the presence of chlorophyll in leaf cells plays a critical role in absorbing light energy, further enhancing the plant's ability to perform photosynthesis effectively. While leaves do play a role in gas exchange by absorbing carbon dioxide, this function is secondary to their primary role in harnessing sunlight for energy. Similarly, although leaves may contribute to a plant’s overall structure, that support is not their main purpose. Attracting pollinators is also not related to leaf function; this role is typically fulfilled by flowers. Therefore, the ability of leaves to absorb sunlight directly ties to the plant’s survival and growth, establishing it as the most critical purpose.