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Date November 2019 Marks available 1 Reference code 19N.3.SL.TZ0.5
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
Command term Suggest Question number 5 Adapted from N/A

Question

The MRI brain scans show the cerebral hemispheres of two people of the same age, one of whom is suffering from multiple sclerosis and has lost motor functions.

[Source: © Frontiers in Bioscience. Role of MRI in Multiple Sclerosis II: Brain and Spinal
Cord Atrophy, Robert Zivadinov and Rohit Bakshi, 9, 647–664, January 1, 2004]

Identify the structures found at I, II and III.

I:

II:

III:

[2]
a.

Suggest one way in which multiple sclerosis has affected the cerebral hemispheres of the brain.

[1]
b.

The folding of the cerebral hemispheres is extensive and varies between different mammals. Explain briefly the importance of folding of the cerebral hemispheres in humans.

[3]
c.

Markscheme

a. I: skull bone/cranium ✔

b. II: «left cerebral» hemisphere
OR
III: «right cerebral» hemisphere ✔

a.

less white matter
OR
bigger space in the middle/ventricles
OR
overall area/volume of cortex/cerebrum is reduced/space between cortex/cerebrum and cranium bigger/number of folds is reduced
OR
slower nerve transmission
OR
fewer synapses
OR
function of cerebral hemispheres diminished ✔

b.

a. the cerebral hemispheres are responsible for higher order functions ✔

b. the folding permits an increased surface area without increasing the cranium size
OR
permits high surface area to volume ratio ✔

c. increased surface/volume permits more synapses ✔

d. humans have a highly developed/highly folded cerebral cortex ✔

e. folding decreases distances therefore faster communication ✔

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

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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