Advanced Placement (AP) Biology Practice Exam

Which of the following best describes photosynthesis?

1. Conversion of glucose to ATP

2. Breakdown of carbon dioxide in the dark

3. Use of sunlight to produce sugars from water and carbon dioxide

4. Release of oxygen from carbon compounds

The correct answer is: Use of sunlight to produce sugars from water and carbon dioxide

The process of photosynthesis involves the conversion of light energy into chemical energy, specifically in the form of glucose. This occurs primarily in the chloroplasts of plant cells, where organisms harness sunlight to transform carbon dioxide and water into glucose and oxygen. This is a crucial biological process that not only provides energy-rich compounds for the plants themselves but also releases oxygen into the atmosphere, which is essential for the survival of aerobic organisms. One of the key components of photosynthesis is the role of sunlight, which is captured by chlorophyll and other pigments. This energy drives the reactions that convert carbon dioxide (a gas taken from the atmosphere) and water (absorbed through plant roots) into glucose, a simple sugar that serves as an energy source. The overall reaction can be summarized by the equation: 6 CO₂ + 6 H₂O + light energy → C₆H₁₂O₆ + 6 O₂. This understanding aligns closely with the selected option, as it highlights the utilization of sunlight and the production of sugars from water and carbon dioxide as integral to photosynthesis.