Question 21M.1.SL.TZ1.23
| Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.1.SL.TZ1.23 |
| Level | SL | Paper | 1 | Time zone | TZ1 |
| Command term | Question number | 23 | Adapted from | N/A |
A locust is an arthropod. For invertebrate groups, which recognition feature is found only in arthropods?
A. Bilateral symmetry
B. Jointed appendages
C. Wings
D. Segmented body
[1]
B
Only about a third of candidates answered this question correctly and the discrimination index was relatively low. For entirely understandable reasons, candidates' understanding of arthropod classification and the use of recognition features was rather poor. A recognition feature should be possessed by all the members of a group and ideally by no members of other groups. Bilateral symmetry and a segmented body could be rejected because some non-arthropods have them. Wings could be rejected, because among arthropods, only insects have them. The remaining answer, jointed appendages was correct.
