Immune System Questions and Answers

Answer: D

Correct answer: They are all types of white blood cells

All three are leucocytes. What separates them is which arm they serve: macrophages and neutrophils belong to the non-specific innate response, while lymphocytes carry the specific acquired one. So no statement about one arm can cover all three - only the fact that they are all white blood cells.

Answer: D

Correct answer: Complement system

The complement system is a cascade of some thirty plasma proteins. Once triggered - by antibody bound to a surface, or directly by microbial surfaces - it opsonises the pathogen for phagocytosis, recruits inflammatory cells, and assembles the membrane attack complex that punches a hole in the microbe and lyses it. Fibrinogen is for clotting, platelets are cell fragments, and MHC molecules present antigen rather than destroying it.

Answer: C

Correct answer: Tonsils

The tonsils are lymphoid tissue, guarding the entrance to the throat, and belong with the lymph nodes, spleen, thymus and Peyer’s patches. Liver, stomach and kidneys belong to other systems - though the liver does contain resident macrophages, the Kupffer cells.

Answer: C

Correct answer: Plasma cells

An activated B cell divides and matures into plasma cells, which are given over almost entirely to secretion: an expanded endoplasmic reticulum, and an output of thousands of antibody molecules a second, all with the same specificity as the receptor that first met the antigen. Memory cells are the other product of the same activation, but they wait rather than secrete.

Answer: A

Correct answer: Infection

The establishment and multiplication of pathogens in the body is an infection. Inflammation, swelling and pus are consequences - the body’s response to it - rather than the invasion itself.

Answer: B

Correct answer: Immune surveillance

Immune surveillance is the continual patrolling of the body by lymphocytes, which circulate through blood, tissue and lymph, passing through the lymph nodes, so that an antigen appearing anywhere is met by the cells that recognise it. It is also the mechanism credited with picking off cells that have turned cancerous.

Answer: C

Correct answer: In the liver

Haematopoiesis moves about during development: it begins in the yolk sac, and through most of gestation the fetal liver is the main site, with the spleen contributing. Only towards the end does the bone marrow take over, and it remains the site for life.

Answer: A

Correct answer: B lymphocytes

Antibodies are made by B lymphocytes - strictly, by the plasma cells they become once activated. T lymphocytes carry the cell-mediated response and help B cells but secrete no antibody; neutrophils and macrophages phagocytose.

Answer: C

Correct answer: Cardiac glycosides

Cardiac glycosides are plant compounds such as digoxin, which act on the heart by inhibiting the sodium-potassium pump. They have nothing to do with immunity. Lymphocytes, antibodies and lymph nodes are all central parts of the vertebrate immune system.

Answer: B

Correct answer: Memory cells

Memory cells are the long-lived survivors of a response. They persist for years without secreting antibody, and on meeting the same antigen again they mount a response that is faster, larger and of higher affinity than the first - which is what vaccination is for, and why most childhood infections are had only once.