Biology Test Immunology 4

Question 1

Which cytokine is known as the 'master regulator' of Th1 cell differentiation?

Accepted Answer

IL-12

Answer

IL-12, produced mainly by dendritic cells and macrophages, drives naive T cells to differentiate into Th1 cells that produce IFN-γ.

Question 2

What is the significance of the RAG1 and RAG2 enzymes in lymphocyte development?

Accepted Answer

They catalyze V(D)J recombination to generate diverse antigen receptors

Answer

RAG1 and RAG2 (recombination activating genes) are essential for V(D)J recombination, the process that generates the enormous diversity of B cell and T cell receptors.

Question 3

Which complement protein forms the membrane attack complex (MAC)?

Accepted Answer

C5b-9

Answer

The membrane attack complex (MAC) is formed by complement proteins C5b, C6, C7, C8, and multiple C9 molecules, creating pores in target cell membranes.

Question 4

A patient develops symptoms 48–72 hours after exposure to an antigen. Which type of hypersensitivity is most likely?

Accepted Answer

Type IV (delayed-type)

Answer

Type IV hypersensitivity is T cell-mediated and takes 48–72 hours to develop, as seen in contact dermatitis and the tuberculin skin test.

Question 5

What distinguishes central tolerance from peripheral tolerance in the immune system?

Accepted Answer

Central tolerance eliminates self-reactive cells during development; peripheral tolerance controls mature autoreactive cells

Answer

Central tolerance occurs in the thymus (T cells) and bone marrow (B cells) to eliminate strongly self-reactive lymphocytes during development, while peripheral tolerance controls any self-reactive cells that escape into circulation.

Biology Practice Test

Biology Practice Test

Biology Test Immunology 4