IB Biology A2.2 Cell structure: practice questions

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A2.2-01 · Paper 1A style · multiple choice · 1 mark

Actual size from a micrograph

In an electron micrograph with a magnification of ×15 000, a mitochondrion is 45 mm long. What is the actual length of the mitochondrion? [1]

1. 0.003 µm
2. 0.3 µm
3. 3 µm
4. 30 µm

Show the answer and the reasoning

Answer: C. Actual size = image size ÷ magnification = 45 mm ÷ 15 000 = 0.003 mm. There are 1000 µm in 1 mm, so 0.003 mm = 3 µm, a typical length for a mitochondrion. 0.003 µm forgets to convert from millimetres. 0.3 µm and 30 µm come from converting with the wrong factor (100 or 10 000 instead of 1000).

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The 5 questions in A2.2

1. A2.2-01 Actual size from a micrographPaper 1A style · multiple choice · 1 mark
2. A2.2-02 Cells with unusual numbers of nucleiPaper 1A style · multiple choice · 1 mark
3. A2.2-03 Locating a protein in a cellPaper 1A style · multiple choice · 1 mark
4. A2.2-04 Structure of a bacteriumPaper 2 style · short answer · 7 marks
5. A2.2-05 Measuring cells with a graticulePaper 1B style · data-based · 8 marks

More of A Unity and diversity

• A1.1 Water
• A1.2 Nucleic acids
• A2.1 Origins of cells
• A2.3 Viruses
• A3.1 Diversity of organisms
• A3.2 Classification and cladistics
• A4.1 Evolution and speciation
• A4.2 Conservation of biodiversity

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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.