Three vertebrates have limbs with the same basic arrangement of bones. Scientists compared the DNA base sequences of the same gene in each pair of species. The table shows the number of differences between each pair of sequences.
| Species compared | Number of DNA sequence differences |
|---|---|
| Gecko and hawk | 8 |
| Gecko and kangaroo | 21 |
| Hawk and kangaroo | 19 |
Compare the DNA results and explain what they suggest about the shared limb arrangement.
85 exam-style questions on Edexcel GCSE Biology 4.1 Evolution and natural selection, covering 4.1.1 Work of Darwin and Wallace and 4.1.2 Resistant organisms and evolution. Each one has a worked solution and a mark scheme showing where the marks go.