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Practice · Biology · 2025 syllabus · B2.1

IB Biology B2.1 Membranes and membrane transport: practice questions

6 exam-style questions on B2.1 Membranes and membrane transport, SL and HL, 1 marked HL: 3 multiple choice, 1 data-based, 1 short answer and 1 extended response. Each one comes with the mark scheme, a model answer and the reasoning behind every mark. Free with your email.

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B2.1-02 · Paper 1A style · multiple choice · 1 mark

Carbohydrate chains on membranes

Which describes the carbohydrate part of glycoproteins in the plasma membrane? [1]

  1. On the cytoplasmic side; attaches the membrane to the cytoskeleton
  2. Within the hydrophobic core; carries glucose across the membrane
  3. On the extracellular side; involved in cell recognition and adhesion
  4. On both surfaces; hydrolyses substrates at the cell surface
Show the answer and the reasoning

Answer: C. C is correct. The carbohydrate chains of glycoproteins and glycolipids always face outwards into the extracellular fluid, where they act as recognition markers (the ABO blood group antigens are an example) and help cells adhere to each other. A puts the chains on the wrong side of the membrane. B is impossible because hydrophilic sugar chains cannot sit in the hydrophobic core, and carrying glucose is a job for transport proteins. D is wrong about location, and breaking down substrates is done by enzymes, not by the carbohydrate chains.

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The 6 questions in B2.1

  1. B2.1-01 Evidence for active uptakePaper 1A style · multiple choice · 1 mark
  2. B2.1-02 Carbohydrate chains on membranesPaper 1A style · multiple choice · 1 mark
  3. B2.1-03 Sodium–potassium pump and chargePaper 1A style · multiple choice · 1 mark · HL
  4. B2.1-04 Osmosis and aquaporinsPaper 2 style · short answer · 7 marks
  5. B2.1-05 Temperature and membrane leakagePaper 1B style · data-based · 8 marks
  6. B2.1-06 Membrane structure and transportPaper 2 style · extended response · 15 marks

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Every Biology and Chemistry question here is original, written for practice in the style of the papers set since the 2025 syllabus, with invented data. Developed independently from the International Baccalaureate Organization, which has not endorsed it. Found a mistake? Email vytis@limeadmissions.com with the question id.