UPSC Prelims 2010 Q123: Science & Technology – Biology
- (a) Breakdown of proteins into amino acids
- (b) Breakdown of glucose into CO₂ and H₂O
- (c) Conversion of glucose into glycogen
- (d) Conversion of amino acids into proteins
Answer: (a) Breakdown of proteins into amino acids
Explanation
Identifying the digestive process
Digestion specifically means breaking down complex food molecules into simpler, absorbable units.
| Option | Verdict | Reason |
|---|---|---|
| (a) Breakdown of proteins into amino acids | Correct | This is a classic digestive process: large protein molecules are broken down into their simpler amino acid building blocks for absorption |
| (b) Breakdown of glucose into CO2 and H2O | Incorrect | This describes cellular respiration, an energy-release process, not digestion |
| (c) Conversion of glucose into glycogen | Incorrect | This describes glycogenesis, a storage/metabolic process, not digestion |
| (d) Conversion of amino acids into proteins | Incorrect | This describes protein synthesis, a biosynthetic process, not digestion |
Digestion vs other metabolic processes:
| Process | Category |
|---|---|
| Protein → amino acids | Digestion |
| Glucose → CO2+H2O | Respiration |
| Glucose → glycogen | Storage (glycogenesis) |
| Amino acids → proteins | Synthesis |
Answer: (a) Breakdown of proteins into amino acids.
Why each option is right or wrong
- (a) CORRECT. Breaking down proteins into amino acids is a classic digestive process.
- (b) Incorrect. This describes cellular respiration, an energy-release process, not digestion.
- (c) Incorrect. This describes glycogen storage (glycogenesis), a metabolic process, not digestion.
- (d) Incorrect. This describes protein synthesis, a biosynthetic process, not digestion.
Key point
Digestion specifically means breaking large food molecules into simpler absorbable units — breaking PROTEINS into AMINO ACIDS is digestion; respiration, glycogenesis, and protein synthesis are different metabolic processes.
Remember
Digestive process: breakdown of proteins into amino acids — NOT respiration, glycogen storage, or protein synthesis.
Common mistakes
- Confusing digestion (breakdown for absorption) with respiration (breakdown for energy release).
- Mixing up glycogenesis (storage) and protein synthesis (biosynthesis) with the actual digestive process.
- Not recognising that digestion specifically means breaking complex molecules into simpler ones for absorption, not any general biochemical breakdown.
Exam tip
Digestion = breaking complex food molecules (like proteins) into simple absorbable units (amino acids). Respiration, storage, and synthesis are separate metabolic categories.
Sources
- NCERT — Biology, digestion and absorption of nutrients
- John E. Hall — Guyton and Hall Textbook of Medical Physiology (Digestion and Absorption in the Gastrointestinal Tract)