Species P and Q have similar body shapes and live in water. Species R has a different body shape and lives on land.
Comparisons of many corresponding DNA regions consistently show that P is more similar to R than to Q.
Which proposed tree and assessment of the evidence are best supported?
P branches with Q; their common habitat independently confirms their close ancestry.
P branches with Q; their common shape outweighs the evidence from many molecules.
P branches with R; their molecular similarities establish that R descended directly from P.
P branches with R; their molecular similarities can outweigh similarities in external shape.
40 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.