Q1. [1] § 5.1 WHAT ARE LIFE PROCESSES? § 5.2.1 Autotrophic Nutrition § 5.3 RESPIRATION
Pravin was given a list of characteristics associated with the process of anaerobic respiration in humans, in the table given below :
Characteristic (i) Muscle Cell (ii) Requires presence of Oxygen (O₂) and Carbon dioxide (CO₂) (iii) 3-Carbon molecules
Which of the above characteristics is/are related to the above process ?
- (A) (i) and (ii)
- (B) (i) and (iii)
- (C) (ii) and (iii)
- (D) (i) only
Previously asked in CBSE board exam
2026 31/3/1 Q1
Generated by claude-sonnet-4-6 · 2026-06-11 09:52 · grounding rag
Model Answer
(B) (i) and (iii)
Anaerobic respiration in human muscle cells occurs without oxygen, producing lactic acid — a 3-carbon molecule. Hence characteristics (i) and (iii) are correct.
Explanation
- Anaerobic respiration in muscles does not require oxygen (so characteristic ii is wrong).
- It occurs in muscle cells when oxygen is insufficient (characteristic i ✓).
- Pyruvate → lactic acid, which is a 3-carbon molecule (characteristic iii ✓).
- Examiners expect you to recall that anaerobic respiration in humans produces lactic acid (3C), not ethanol.
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