Generated by claude-sonnet-4-6 · 2026-06-11 09:47 · grounding rag
Model Answer
(i) ATP acts as the energy currency of the cell. The energy released during cellular respiration is used to synthesise ATP from ADP and inorganic phosphate. This ATP is then broken down to release energy (30.5 kJ/mol) to drive all endothermic reactions and life processes in the cell.
(ii) In plants, large intercellular spaces ensure that all cells remain in contact with air. Gases are exchanged through stomata. This ensures sufficient exchange of gases throughout the plant body.
(iii) The direction of diffusion of gases in plants depends upon:
- The environmental conditions, and
- The requirements of the plant (e.g., at night, CO₂ is released; during the day, O₂ is released as CO₂ is used in photosynthesis).
Source: Chapter 5, Section 5.3 Respiration
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Explanation
- For (i), the key phrase examiners look for is "energy currency" and the idea that ATP stores and releases energy for cellular activities.
- For (ii), mention stomata and intercellular spaces — both are expected.
- For (iii), state both factors clearly: environmental conditions and plant's requirements. Giving the day/night example strengthens the answer and is directly from the textbook.