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

What is the role of chlorophyll in photosynthesis?

1. To absorb water

2. To facilitate chemical reactions

3. To absorb sunlight

4. To transport nutrients

The correct answer is: To absorb sunlight

Chlorophyll plays a crucial role in photosynthesis by absorbing sunlight. This green pigment, found mainly in the chloroplasts of plant cells, captures light energy, primarily in the blue and red wavelengths, and initiates the process of converting that light energy into chemical energy. This absorbed energy is vital for driving the series of reactions that convert carbon dioxide and water into glucose and oxygen. Without chlorophyll, plants would not be able to efficiently harness solar energy, and the entire process of photosynthesis would be impaired, affecting the plant's ability to produce food and release oxygen into the atmosphere. The incorrect options refer to functions not performed by chlorophyll in photosynthesis. For instance, chlorophyll does not absorb water, as that process primarily involves root uptake from the soil. While chlorophyll contributes to the chemical reactions of photosynthesis, its main role is energy absorption rather than being solely responsible for facilitating reactions. Additionally, chlorophyll does not transport nutrients; nutrient transport occurs through the plant's vascular system, particularly xylem and phloem.