Which of the following is the primary purpose of cellular respiration in eukaryotic cells?

• A. To synthesize glucose from sunlight
• B. To convert glucose into usable ATP energy
• C. To break down ATP into glucose
• D. To produce oxygen from carbon dioxide

Answer: (B)

Verified step by step guidance

1. Understand the process of cellular respiration: Cellular respiration is a metabolic process that occurs in the mitochondria of eukaryotic cells. Its primary purpose is to convert the chemical energy stored in glucose into a usable form of energy, ATP (adenosine triphosphate).
2. Eliminate incorrect options: The first option, 'To synthesize glucose from sunlight,' describes photosynthesis, not cellular respiration. Photosynthesis occurs in plants, algae, and some bacteria, not in the mitochondria of eukaryotic cells.
3. Analyze the second option: 'To convert glucose into usable ATP energy' accurately describes the main function of cellular respiration. Glucose is broken down through glycolysis, the citric acid cycle, and the electron transport chain to produce ATP.
4. Evaluate the third option: 'To break down ATP into glucose' is incorrect because ATP is not broken down to form glucose. Instead, ATP is the energy currency produced during cellular respiration.
5. Evaluate the fourth option: 'To produce oxygen from carbon dioxide' is incorrect because cellular respiration consumes oxygen and produces carbon dioxide as a byproduct, not the other way around.