Question 19M.3.HL.TZ1.c
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.HL.TZ1.c |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Outline | Question number | c | Adapted from | N/A |
The diagram shows part of the embryonic development in a clawed toad of the genus Xenopus.
[Source: © International Baccalaureate Organization 2019]
Outline the consequences of incomplete closure of the neural tube in humans.
[2]
a. this leads to condition spina bifida ✔
b. some of the vertebrae may not form correctly
OR
incomplete closing of the backbone ✔
c. spinal cord may protrude ✔
d. «may» cause paralysis ✔
Candidates’ answers to this question tended to be good predictors of how well they scored on the whole option. Students with little to no knowledge and understanding scored 0 marks. An equal number were able to score 1 mark, usually the marking point for identifying the result as spina bifida, while students who scored well on the whole paper successfully communicated another aspect of the condition. This question is also a good example of the need for students to understand what is being asked first. The question asks students to outline the consequences, but a number of students wrote in some detail about the effect of folic acid deficiency during pregnancy as a cause. One reason for this response may be that the cause of spina bifida has been a question in a recent paper.
