Immune System Questions and Answers

Answer: C

Correct answer: Acquired through readymade antibodies

Passive immunity means the antibodies are supplied rather than made - across the placenta, in breast milk, or by injection of antiserum or immunoglobulin. Protection is immediate but short-lived, and no memory is left, because the recipient’s own immune system was never engaged.

Answer: B

Correct answer: Thymosin

Thymosin, secreted by the thymus, drives the maturation and differentiation of T lymphocytes. Cortisol and other steroids suppress immune activity rather than promote it, and thyroxine governs metabolic rate.

Answer: C

Correct answer: Antibodies

Passive immunity is conferred by injecting ready-made antibodies - antiserum or immunoglobulin, as after a snake bite or a possible tetanus exposure. Protection begins at once but fades in weeks. A vaccine does the opposite: it supplies antigen and makes the body produce its own response.

Answer: A

Correct answer: Antigen A and antibody b

In the ABO system a person carries the antigen of their own group and the antibody against the other. Group A red cells therefore bear antigen A, and the plasma contains anti-B. Having anti-A as well would destroy the person’s own cells.

Answer: C

Correct answer: Pre-T cells

All blood cells arise in the bone marrow, but the pre-T cell is the one that leaves before it is finished: it migrates to the thymus, where it rearranges its receptor genes and is selected. Erythroblasts, myeloblasts and NK precursors all complete their development in the marrow.

Answer: B

Correct answer: Active acquired immunity

Resistance built in response to an antigenic stimulus - an infection or a vaccine - is active acquired immunity: the body made the response itself and retains memory cells. Passive immunity involves no antigenic stimulus at all, since the antibodies arrive ready-made.

Answer: B

Correct answer: Haemolytic disease

If an Rh-negative mother has been sensitised to the Rh antigen, her anti-Rh IgG crosses the placenta and attacks the red cells of an Rh-positive foetus - haemolytic disease of the newborn. The first such pregnancy is usually safe, because sensitisation happens mainly at delivery; later ones are at risk, which anti-D immunoglobulin given to the mother now prevents.

Answer: A

Correct answer: Monkey

The factor takes its name from the rhesus monkey, in whose red cells Landsteiner and Wiener first raised antibodies to it in 1940, before the corresponding human antigen was recognised.

Answer: B

Correct answer: Epitopes

An epitope (antigenic determinant) is the small part of an antigen that an antibody actually binds - a few amino acids or sugar residues on the surface. A single large antigen carries many different epitopes, which is why one protein provokes many different antibodies.

Answer: D

Correct answer: All the above

All three are white cells of the defence system: neutrophils are the first phagocytes to arrive at an infection, macrophages engulf and also present antigen, and lymphocytes carry the specific response. Between them they cover both the innate and the acquired arms.