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Biological molecules
Practice Questions

40 CIE IGCSE Biology questions on Biological molecules, each with instant feedback and a full examiner-style mark scheme.

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✨ Revision guide includes key terms, worked examples and exam technique for Biological molecules.

Try 2 sample questions on Biological molecules

Question 1 · 1 mark · Difficulty 1/3

A student tests a food sample with Benedict's reagent and observes a brick-red precipitate. Which conclusion is correct?

  1. A non-reducing sugar is present in the sample
  2. A reducing sugar is present in the sample
  3. Protein is present in the sample
  4. Starch is present in the sample
Show answer & explanation
✓ Answer: B — A reducing sugar is present in the sample
Benedict's reagent turns brick-red (or orange/red) in the presence of a reducing sugar such as glucose or maltose, because the sugar reduces copper(II) ions to copper(I) oxide. A non-reducing sugar such as sucrose would give a negative Benedict's test unless first hydrolysed. Starch is detected by iodine solution turning blue-black. Protein is detected using the Biuret reagent, which turns purple/violet.
Question 2 · 1 mark · Difficulty 1/3

Which elements are present in all carbohydrates?

  1. Carbon, hydrogen and nitrogen
  2. Carbon and nitrogen only
  3. Nitrogen, oxygen and sulfur
  4. Carbon, hydrogen and oxygen
Show answer & explanation
✓ Answer: D — Carbon, hydrogen and oxygen
Carbohydrates contain carbon, hydrogen and oxygen only. Nitrogen is the additional element found in proteins.
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CIE IGCSE Biology: Biological molecules FAQ

Is Kramizo free for CIE IGCSE students preparing for Biology?
Yes — completely free. Every student gets 45 questions a day on the free plan, with no card required and no trial countdown. That free quota works across every subject and every topic in our bank, so you can mix Biological molecules practice with other Biology topics or even switch to a totally different CIE subject without paying anything. Kramizo's optional Pro plan removes the daily cap and adds detailed progress analytics, but the free tier is the real product — used by thousands of GCSE, IGCSE and CSEC students.
Are the Biological molecules questions aligned to the official CIE IGCSE Biology syllabus?
Every question is written against the published CIE IGCSE Biology specification, including the exact command words (state, describe, explain, calculate, evaluate, etc.), mark allocations, and difficulty tier you'd see on a real CIE paper. Explanations are written in the style of official examiner mark schemes — they tell you what is being awarded marks and why distractors are wrong, not just whether you got it right. The bank is continually refined to match the latest syllabus updates from CIE.
How is Biological molecules typically tested on CIE IGCSE Biology papers?
Biological molecules appears across multiple question types on real CIE IGCSE Biology papers — most commonly as multiple-choice questions in the objective section, structured short-answer questions in the main paper, and occasionally as part of an extended response. Kramizo's practice bank reflects that mix: 4-option MCQs, true/false statements, fill-in-the-blank key terms, multi-select questions, and ordering questions. Working through the bank gives you exposure to every question style examiners actually use.

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