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

What role does chlorophyll play in photosynthesis?

1. It releases glucose

2. It absorbs sunlight

3. It generates oxygen

4. It splits hydrogen ions

The correct answer is: It absorbs sunlight

Chlorophyll plays a crucial role in photosynthesis by absorbing sunlight. This pigment, primarily found in the chloroplasts of plant cells, is responsible for capturing light energy, which is essential for the photosynthetic process. When chlorophyll absorbs sunlight, it energizes electrons, initiating a series of reactions that convert light energy into chemical energy. This energy is then used to convert carbon dioxide and water into glucose, a form of sugar that plants use for energy and growth. In the context of photosynthesis, the other choices do not accurately describe the primary function of chlorophyll. While oxygen is a byproduct generated during this process and glucose is produced as well, chlorophyll itself does not release glucose or generate oxygen directly. The splitting of hydrogen ions is part of the broader process of converting light energy into chemical forms but is not the specific role of chlorophyll either. Thus, the absorption of sunlight by chlorophyll is critical to the entire process of photosynthesis, making it essential for plant life.