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.
1Define3 marks
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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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What is meant by the allele frequency of a population?
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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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Define the term evolution.
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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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Which of the following is the only source of brand-new alleles in a population?
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Under the biological species concept, which observation confirms that two organisms belong to the same species?
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Outline how mutation, meiosis and sexual reproduction each contribute to heritable variation in a population.
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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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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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Which statement is the best definition 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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Which statement best defines adaptive radiation?
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The diagram shows the same population at two times, many generations apart.
The dark allele is shaded.
What does the change shown represent?
[Diagram: bio-gene-pool {"startDarkPercent": 20, "endDarkPercent": 75}]
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A student lists possible evidence for evolution.
Which item is NOT valid evidence and should be removed from the list?
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A flowering plant suddenly gives rise to a new species in a single generation because its chromosome number has doubled, so it can no longer breed with its parent population.
Which pattern of speciation is this?
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At the genetic level, evolution is best described as a change in which of the following?
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Two long-isolated populations of snails are brought back together.
At what point can they finally be described as two separate species?
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