Exam Focus

Exam Focus

Plant transport questions appear frequently across all GCSE Biology specifications. Edexcel 1BI0 Paper 2 (Topic 6: Plant Structures and Their Functions) tests this with stimulus-based questions — you may be given a diagram of xylem or phloem structure, or data from a potometer experiment, and asked to explain or evaluate. The "Compare" command word is common on Edexcel for xylem vs phloem questions. These are the most commonly tested areas:

• 6-mark comparison table (Higher tier): "Compare the structure and function of xylem and phloem." Examiners expect: cell status (dead/living), wall reinforcement (lignin/sieve plates), substances transported, direction of flow, energy requirement. Award yourself 1 mark per clear, correct distinction.
• Root hair cell adaptations (2-3 marks): "Explain how root hair cells are adapted for their function." Link each feature to its purpose: long projection → large surface area → faster absorption rate. Never list a feature without explaining why it matters.
• Translocation vs transpiration (2-4 marks): Know the difference. Transpiration = water loss from leaves. Translocation = movement of sugars in phloem. Common exam trap: students confuse which vessel carries which substance.
• "Explain why xylem vessels are dead" (2 marks): State that hollow lumen allows unobstructed water flow, and lignified walls prevent collapse under tension.
• Command word "compare": Always give both sides (xylem AND phloem, or plant AND animal). A one-sided answer cannot score comparison marks.
• Required Practical questions: Expect questions on the potometer method and why the shoot is cut underwater (to prevent air bubbles entering xylem and blocking water flow).

Most common command words: describe, explain, compare, suggest, evaluate.