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6.4 Classification of living organisms

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Question 14

Scientists are investigating the ancestry of three living species of freshwater crustacean: J, K and L.

Two fossils are from the lineage that led to species J.

FossilAge (million years)Ridged body plateFan-shaped tail
U74PresentAbsent
V49PresentPresent

The table shows the features of the living species.

SpeciesRidged body plateFan-shaped tail
JPresentPresent
KPresentAbsent
LAbsentAbsent

Scientists assume that each feature evolved only once and was not subsequently lost.

Two models have been proposed:

  • Model 1: L separated first from the lineage leading to J and K. J and K separated later.
  • Model 2: K separated first from the lineage leading to J and L. J and L separated later.
a.

Suggest the order in which the two features evolved. Use the fossil data.

[2]
b.

Which model is better supported by all the evidence? Explain your answer.

[3]
Markscheme

6.4 Classification of living organisms Questions

  1. GCSE
  2. /Biology
  3. /6.4 Classification of living organisms

81 exam-style questions on AQA GCSE Biology 6.4 Classification of living organisms, covering 6.4 Classification of living organisms. Each one has a worked solution and a mark scheme showing where the marks go.

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