CAIE A Level Biology 9700 · Selection and evolution
The table shows the percentage similarity in a mitochondrial DNA sequence among three species of a genus of rodents found on different islands.
| Species pair | DNA sequence similarity (%) |
|---|---|
| A and B | 98.2 |
| A and C | 96.5 |
| B and C | 97.8 |
Outline how the data in the table can be used to support the theory of evolution and explain how speciation between these species may have occurred.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Outline means: Give the main points briefly. Less detail than describe, but every key step has to be there. One short line per step, in order. The marks are for coverage, not depth.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.