Edexcel IGCSE Biology 4BI1: Frequent mistakes

Pearson Edexcel Principal Examiner Feedback for Biology 4BI1 identifies recurring misconceptions and exam technique errors. Avoiding these can improve your grade.

Command word confusion

Describe vs. explain

Students frequently confuse describe and explain. Describe = what/how; Explain = why. Many lack the depth and detail required for higher marks.

Fix: Describe = account of features or process. Explain = reasons; use “because”; link cause and effect.

Precision in terminology

Precise scientific terminology is essential but often lacking. Vague wording scores partial credit.

Fix: Use syllabus terms. “Lymphocytes produce antibodies” not “white blood cells produce antibodies”. “Mitochondria” not “energy factories”.

Energy in food chains

Energy “lost” or “excretion”

Many incorrectly state that energy used in growth is “lost” from food chains. Energy used for growth is transferred to the next trophic level. Confusion between excretion of indigestible parts (faeces) and excretion of metabolic waste (urea).

Fix: Energy lost = not passed on (respiration, heat, faeces). Indigestible parts = faeces (not assimilated). Metabolic waste = urea, CO₂.

Food chain terminology

Confusion between producers, primary consumers and secondary consumers. Energy transfer (≈10%) vs. energy loss.

Fix: Producer → primary consumer → secondary consumer. Most energy lost at each step (respiration, heat, excretion).

Detailed knowledge requirements

Vague answers

Many provide vague answers lacking specificity. “White blood cells” instead of “lymphocytes”; “enzymes” not named.

Fix: Be specific. Name the cell type, enzyme, or structure. Match the level of detail in the mark scheme.

Standard form

Candidates frequently fail to convert to standard form when required (e.g. 0.0005 → 5 × 10⁻⁴).

Fix: Check if standard form is required. Use correct format (a × 10ⁿ, 1 ≤ a < 10).

General exam technique

• Show working for calculations and magnification
• State = short; Describe = what/how; Explain = why
• Suggest = apply to the scenario—generic answers score poorly
• Use correct units—mm, µm, percentage

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Based on Pearson Edexcel IGCSE Biology 4BI1 Principal Examiner Feedback (2021–2023).