Scientists compare the forelimbs of three vertebrates.
Table
| Vertebrate | Upper and lower limb bones | Digits | Main function |
|---|---|---|---|
| P | one upper bone and two lower bones | five | grasping |
| Q | one upper bone and two lower bones | five, elongated | flying |
| R | one upper bone and two lower bones | five, shortened | swimming |
Which explanation accounts for the complete pattern?
three unrelated limb plans became identical because all three functions involve movement
an inherited limb plan remained unchanged because all three functions involve movement
an inherited limb plan was modified in different ways for different functions
three unrelated limb plans were inherited after individuals changed their own bone lengths
45 exam-style questions on Edexcel GCSE Biology 4.2 Evidence for evolution and classification, covering 4.2.1 Fossil evidence for human evolution, 4.2.2 Stone tool evidence for human evolution, 4.2.3 Pentadactyl limb as evidence, and 4.2.4 Three domains classification. Each one has a worked solution and a mark scheme showing where the marks go.