| Date | May 2017 | Marks available | 2 | Reference code | 17M.3.HL.TZ2.4 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Distinguish | Question number | 4 | Adapted from | N/A |
Question
The images show the early stages and completed outcome of the process of neurulation.
Label the parts I and II on the images.
Structure Y will eventually elongate to form two structures. State the names of these two structures.
1.
2.
State the condition that arises if the closure of structure X is incomplete during embryonic development.
The diagrams show a rat brain and a human brain. They are not drawn to scale.
Distinguish between the cerebral cortex of the human brain and of the rat brain.
Markscheme
a. I: neural groove/plate/fold
b. II: ectoderm
a. brain
b. spinal cord
spina bifida
a. human cortex larger than rat cortex
b. human cortex proportionally larger than other brain parts than rat cortex OWTTE
c. surface area «of cortex» larger for humans
d. more infolding of the surface of the cerebral cortex in humans
