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✅ Correct Answer: B — Cellular respiration
Cellular Respiration is the biochemical process by which cells convert glucose into energy (ATP). The equation is: Glucose (C6H12O6) + Oxygen (6O2) → Carbon dioxide (6CO2) + Water (6H2O) + Energy (ATP). This occurs in three stages: Glycolysis (cytoplasm), Krebs Cycle (mitochondria), and Electron Transport Chain (mitochondria).
❌ Why other options are wrong:
• A. Photosynthesis — Photosynthesis is the opposite process; it occurs in plants (chloroplasts) and uses sunlight + CO2 + water to produce glucose and oxygen. Humans cannot do photosynthesis.
• C. Digestion — Digestion breaks down food into smaller molecules (like glucose) in the digestive system; it is not the process of energy production from glucose.
• D. Excretion — Excretion is the elimination of metabolic waste products (urea, CO2, urine); not related to energy production.
📝 Important Note: Cellular Respiration = energy production from glucose. ATP = Adenosine Triphosphate = energy currency of cells. Mitochondria are the site of cellular respiration. 1 glucose molecule yields 36-38 ATP molecules. SSC CGL important cell biology concept.
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