Q1. [3] medium thorough-understanding
Distinguish between xylem and phloem transport in plants with respect to: (i) substances transported, (ii) direction of transport, and (iii) energy requirement.
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding rag
Model Answer
| | Xylem | Phloem |
|---|---|---|
| (i) Substances transported | Water and dissolved minerals | Prepared food (sucrose, amino acids) |
| (ii) Direction | Unidirectional — roots to leaves (upward) | Bidirectional — from leaves to other parts |
| (iii) Energy requirement | No energy (ATP) required; driven by transpiration pull | Energy (ATP) required to load food into phloem |
Source: Life Processes, Chapter 5
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Explanation
- This is a standard 3-mark distinction question — one mark per point (substances, direction, energy).
- A table format is ideal here; it is neat, clear, and examiners can award marks quickly.
- Key words to use: transpiration pull (xylem, passive), ATP/energy (phloem, active), bidirectional (phloem).
- Do not confuse: xylem carries water/minerals (inorganic); phloem carries food (organic, made by photosynthesis).