Advanced Placement (AP) Biology Practice Exam

What is the primary function of chlorophyll?

1. Absorb water for plant growth

2. Convert sunlight into energy

3. Green pigment essential for photosynthesis

4. Store energy in carbohydrates

The correct answer is: Green pigment essential for photosynthesis

Chlorophyll's primary function revolves around its role in photosynthesis, which is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored as glucose. Chlorophyll primarily absorbs light, particularly in the blue and red wavelengths, while reflecting green light, which is why plants appear green. This absorption of light energy is crucial for the subsequent biochemical reactions that convert carbon dioxide and water into glucose and oxygen. The other options, while related to plant biology, do not describe the primary role of chlorophyll. Absorbing water is a function more associated with root systems and the overall physiology of the plant rather than chlorophyll itself. The conversion of sunlight into energy is a broader description of the process of photosynthesis, but does not specifically highlight chlorophyll's role as the pigment that captures light. Finally, while chlorophyll plays a role in creating carbohydrates, it does not act as a storage molecule but instead is involved in the initial stages of energy capture needed for producing those carbohydrates.