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

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

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of cellular respiration. Cellular respiration is a metabolic process that occurs in eukaryotic cells to convert biochemical energy from nutrients, primarily glucose, into adenosine triphosphate (ATP), which is the usable form of energy for cellular functions.
2. Step 2: Eliminate incorrect options based on the definition of cellular respiration. For example, 'To produce oxygen from carbon dioxide' is incorrect because cellular respiration consumes oxygen and produces carbon dioxide as a byproduct.
3. Step 3: Evaluate the option 'To synthesize glucose from sunlight.' This describes photosynthesis, not cellular respiration, so it is also incorrect.
4. Step 4: Consider the option 'To break down ATP into glucose.' This is incorrect because ATP is not broken down into glucose; rather, glucose is broken down to produce ATP during cellular respiration.
5. Step 5: Identify the correct answer: 'To convert glucose into usable ATP energy.' This accurately describes the primary purpose of cellular respiration, which is to generate ATP from glucose to power cellular activities.