DP Biology (first assessment 2025)
Question 21M.2.SL.TZ1.5a.ii
| Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.2.SL.TZ1.5a.ii |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | a.ii | Adapted from | N/A |
a.ii.
[Maximum mark: 1]
21M.2.SL.TZ1.5a.ii
(a.ii)
The bird and bat wings share homologous bone structures whereas the insect wing does not. Outline the conclusion that can be drawn about the evolution of these wings, based on homologous structures.
[1]
Markscheme
a. bird and bat share a more recent common ancestor (than the insect) ✔
b. bird and bat are more closely related than insect and bat / insect and bird ✔
c. bird and bat wings evolved from a common ancestor (by natural selection) ✔
Examiners report
Candidates found it hard to express themselves without contradiction.
In both parts the key to successful answers was in using the organisms given in the example. Contradictions were thus avoided.
