Principles of science

Question 1

Why does the immune system require TWO classes of Major Histocompatibility Complex molecules (MHC Class I AND MHC Class II) ?

1. It allows the immune system to discriminate between intracellular and extracellular pathogens.
2. MHC Class I is required for B cell recognition of antigen, whereas MHC Class II is required for T cell recognition of antigen.
3. MHC Class I is part of the innate immune system whereas MHC Class II is part of the adaptive immune system.
4. It allows the immune system to discriminate between bacterial infection and parasite infection.
5. MHC Class I is required for T cell development in the thymus, whereas MHC Class II is involved in T cell recognition of antigen in the lymph nodes.

Answer 1

1. It allows the immune system to discriminate between intracellular and extracellular pathogens.

Question 2

Why would B cells/ plasma cells produce IgE antibody instead of IgG antibody ?

1. IgE is important for parasite infections and assists mast cell responses.
2. This is produced in the MALT and is the most important antibody for mucosal defence.
3. IgE is better at neutralising viruses than IgG.
4. IgE is produced against bacteria and is important for triggering formation of the complement membrane attack complex.
5. This would occur if there was a lack of T cell help for class-switching.

Answer 2

1. IgE is important for parasite infections and assists mast cell responses.

Question 3

Why do animals need lymph nodes ?

They are the site of lymphocyte activation to antigen.

They are important for lymphocyte development from stem cells.

They are the site of lymphocyte destruction of viruses.

They are the only tissues where lymphocyte responses can occur.

They are required because lymphocytes can only migrate around the body in the lymph.

Answer 3

They are the site of lymphocyte activation to antigen.

Question 4

The signalling molecule that is expressed in the AER and controls outgrowth of the limb along the proximo-distal axis is:

1. Fgf8.
2. Sonic hedgehog (shh)
3. Wnt7a.
4. Bmp4
5. Engrailed (En)

Answer 4

Fgf8

Question 5

For neural crest to form, the dorsal neural tube must come into contact with which of the following tissues?

1. The ectoderm
2. The mesoderm
3. The endoderm
4. The notochord
5. The notochord lies at the ventral edge of the neural tube
6. The lateral plate mesoderm

Answer 5

4. The notochord