Q1. [3] deep thorough-understanding
Trace the journey of a single glucose molecule from its synthesis in a leaf cell to its use in releasing energy in a root cell of the same plant. In your answer, name the tissue that transports it, the energy source used for that transport, and the cellular location where energy is finally released from glucose.
Generated by claude-sonnet-4-6 · 2026-06-26 01:02 · grounding rag
Model Answer
Glucose is synthesised in the chloroplast of leaf cells during photosynthesis. It is then loaded into the phloem tissue, which transports it from the leaf (source) to the root (sink). This transport — called translocation — is an active process that requires ATP energy. Once glucose reaches the root cell, it is broken down during aerobic respiration. The final stage of respiration, where most ATP is released from glucose, occurs in the mitochondria of the root cell.
Source: Life Processes, Chapter 5
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Explanation
- 3 marks = 3 key points: (1) phloem as transport tissue, (2) ATP/energy used for transport, (3) mitochondria as the site of energy release.
- Examiners expect all three named correctly. Saying "vascular tissue" without naming phloem specifically may cost a mark.
- Don't confuse xylem (water/minerals) with phloem (food/glucose).
- The textbook (Exercise Q4) explicitly states energy release from pyruvate happens in the mitochondria — use that exact word.