A scientist compares the front limbs of two vertebrates.
| Feature | Sea turtle | Cat |
|---|---|---|
| Number of upper limb bones | 1 | 1 |
| Number of lower limb bones | 2 | 2 |
| Wrist bones | present | present |
| Number of digits | 5 | 5 |
| Relative length of digits | long | short |
| Main function of limb | swimming | walking and running |
Explain how the information in the table supports the conclusion that sea turtles and cats evolved from a common ancestor, and why their front limbs now differ.
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.