Date | November 2019 | Marks available | 2 | Reference code | 19N.3.SL.TZ0.5 |
Level | Standard level | Paper | Paper 3 | Time zone | TZ0 / no time zone |
Command term | Identify | 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:
Suggest one way in which multiple sclerosis has affected the cerebral hemispheres of the brain.
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.
Markscheme
a. I: skull bone/cranium ✔
b. II: «left cerebral» hemisphere
OR
III: «right cerebral» hemisphere ✔
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 ✔
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 ✔