| Date | May 2013 | Marks available | 1 | Reference code | 13M.1.HL.TZ2.17 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | Question number | 17 | Adapted from | N/A |
Question
What distinguishes Annelida from Platyhelminthes?
A. Platyhelminthes have a segmented body but Annelida do not.
B. Platyhelminthes reproduce sexually but Annelida do not.
C. Platyhelminthes have radial symmetry but Annelida have bilateral symmetry.
D. Annelida have both a mouth and an anus but Platyhelminthes do not.
Markscheme
D
Examiners report
Three teachers expressed concern over this question. Platyhelminthes having only one opening to their digestive tract is a distinguishing feature of most classes and can be arrived at through eliminating the other answers. Answer C was the most commonly chosen incorrect answer. Teachers are encouraged to review the distinction between radial symmetry and bilateral symmetry with their students.
