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Practice · Biology · 2025 syllabus · A4.1

IB Biology A4.1 Evolution and speciation: practice questions

6 exam-style questions on A4.1 Evolution and speciation, 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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A4.1-01 · Paper 1A style · multiple choice · 1 mark

Same bones, different jobs

The forelimbs of a bat, a whale and a mole contain the same set of bones arranged in the same way, but they are used for flying, swimming and digging. What do these forelimbs show? [1]

  1. Analogous structures produced by convergent evolution
  2. Analogous structures produced by divergent evolution
  3. Homologous structures produced by divergent evolution
  4. Homologous structures produced by convergent evolution
Show the answer and the reasoning

Answer: C. The same underlying pentadactyl structure, inherited from a common ancestor, has been modified for different functions: these are homologous structures, and the process is divergent evolution (adaptive radiation). A and B are wrong because analogous structures do a similar job but evolved separately, the opposite of this case. D pairs homologous structures with convergent evolution, which produces similar features from different origins.

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The 6 questions in A4.1

  1. A4.1-01 Same bones, different jobsPaper 1A style · multiple choice · 1 mark
  2. A4.1-02 Separated by an isthmusPaper 1A style · multiple choice · 1 mark
  3. A4.1-03 A new species by polyploidyPaper 1A style · multiple choice · 1 mark · HL
  4. A4.1-04 One protein, five beetlesPaper 2 style · short answer · 6 marks
  5. A4.1-05 Selective breeding in quailPaper 1B style · data-based · 9 marks
  6. A4.1-06 How new species arisePaper 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.