Question

51. What is true about MHC class 2 molecules?

A) The CD8 surface protein is needed for attachment

B) Present exogenous antigens

C) Are found on red blood cells.

D) Trigger release of perforins and fragmentins

E) All of the above

52. Which is false about neuronal development?

A) The brain grows by 2/3 in the first three months after birth

B) Neurons begin to develop by week 3 of embryonic development.

C) In adolescence, new neurons are added to define brain circuits more sharply

D) Synaptic pruning takes place during development

E) The hippocampus and amygdala aren’t fully functional until age 3

54. Which of the following is not an aspect of the blood brain barrier?

A) Hydrophobic molecules can diffuse across the capillaries

B) Astrocytes provide carrier proteins for selective transport

C) Glucose crosses the barrier by GLUT-1 carriers

D) Insulin is transported across the membrane

E) All of the above are true

Answer 1

51. Major histological complex is divided into MHC I and MHC II.
MHC I binds to CD8 receptors in T cells while MHC II presents antigen to CD4 receptor on T cells. So option A is incorrect.

RBC do not express any MHC receptors. So option C is incorrect

MHC ll do not trigger release of perforins and fragmentin. So option D is incorrect.

MHC ll presents pathogen which are extracellular or exogenous.
So the correct answet is B

52. Research shows that 2/3 or 64% of human brain develops by theage of three months in infants. After 3 months the brain growth slows down. So option A is true.
Neuron starts developing from the neural plate by week 3 of embryonic development. So option B is true.
In adolescence, new neurons are added to define brain circuits. So option C

Hipocampus and amygdala becomes fully functional by the age of 21/2 to 3 years. So option E is true.  
Synaptic pruning is the removal of unwanted synapses in the brain that starts from time of birth and ends by the mid 20s. It does not occur during development. So option D is false.
Answer : D

54. Blood brain barrier is the barrier present netween the circulating blood and the brain made pf endothelial cells that is semipermeable to the substances present in the circulating blood.
Blood brain barrier allows entry of hydrophobic molecules and prevent entry of hydrophilic molecules. So option A is true.
Astrocytes are special cells found in brain that acts as tranport protein to carry substances. So optiom B is true.
Blood brain barrier allows passage of glucose through it with the help of GLUT1. So option C is true.
Insulin also crosses blood brain barrier and helps in uptake of insulin by brain cells. So option D is true.
All statements are true. Answer : E.