Natural Science CLEP Prep Practice Exam

Photosynthesis is the process by which plants use energy from the sun to make their own food from water and carbon dioxide. Breathing, metabolism, and cellular respiration all play important roles in a plant's life, but they are not the specific processes involved in photosynthesis. Breathing is a vital function where plants take in oxygen and release carbon dioxide. Metabolism is the chemical reactions occurring in a plant's cells to maintain life. Cellular respiration is the process by which cells release energy from food molecules. These processes are all necessary for a plant's survival, but they are not the main process responsible for creating their own food through photosynthesis. Therefore, option B is the best answer.