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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.

[2]
a.i.

Structure Y will eventually elongate to form two structures. State the names of these two structures.

1. 

2. 

[2]
a.ii.

State the condition that arises if the closure of structure X is incomplete during embryonic development.

[1]
a.iii.

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.

[2]
b.

Markscheme

a. I: neural groove/plate/fold 

b. II: ectoderm

 

a.i.

a. brain 

b. spinal cord

 

a.ii.

spina bifida

a.iii.

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

b.

Examiners report

[N/A]
a.i.
[N/A]
a.ii.
[N/A]
a.iii.
[N/A]
b.

Syllabus sections

Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Core topics) » A.2 The human brain
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Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Core topics)
Option A: Neurobiology and behaviour

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