Unit 1: Unity and Diversity
Topic 1.8: Evolution and Speciation Questions
Practice 20 exam-style questions for IB Biology Topic 1.8. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.
1Identify1 mark
Which statement best defines adaptive radiation?
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A fossil series shows a single mammal lineage changing through a long, unbroken sequence of only-slightly-different forms, leading to one modern species.
State the type of evolution shown by this lineage and its ancestors.
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Outline three different lines of evidence that scientists use to support the theory that today's species evolved from earlier ones.
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A horse and a donkey can mate and produce a mule, but the mule is sterile.
What does this tell us about horses and donkeys?
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Define the biological species concept, and use the example of a horse, a donkey and a mule to show how it is applied.
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Two fish-eating species are found to share almost identical sequences in several of their genes.
Which type of evidence for an evolutionary relationship is this?
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Fossils of a horse-like lineage show a long, unbroken series of forms that each differ only slightly from the one before, leading to the modern animal.
Which pattern of speciation does this best illustrate?
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2026
State one type of evidence that supports the theory of evolution.
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A new river forms and splits one population of monkeys into two groups that can no longer reach each other.
What is the immediate consequence of this separation?
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Over many generations, dairy farmers have repeatedly bred only their highest-yielding cows together, and the herd's average milk yield has steadily risen.
What does this best illustrate?
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Under the biological species concept, which observation confirms that two organisms belong to the same species?
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2026
State the source of the variation on which natural selection acts.
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2026
State one example of a prezygotic barrier to reproduction.
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Which of the following is the only source of brand-new alleles in a population?
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Which statement is the best definition of evolution?
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Outline how mutation, meiosis and sexual reproduction each contribute to heritable variation in a population.
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What is meant by the allele frequency of a population?
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A fossil series shows several related species that gradually diverged from a single common ancestor over time.
Which statement best explains this pattern?
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The image shows how a population changes by natural selection when a predator hunts by sight.
Which statement best matches the process shown?
[Diagram: bio-natural-selection]
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