Scientists compare corresponding DNA regions in species P with those in three other species. For this comparison, a lower percentage of different bases is taken as stronger evidence of a closer relationship.
| Comparison | Number of bases compared | Number of different bases |
|---|---|---|
| P with Q | 400 | 12 |
| P with R | 1500 | 30 |
| P with S | 800 | 20 |
Which conclusion is supported, and which limitation applies?
Q is closest; the results do not prove that P evolved directly from Q.
S is closest; the results do not prove that P evolved directly from S.
R is closest; the results do not prove that P evolved directly from R.
R is closest; the results do not prove that P shares an ancestor with R.
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.