Immune System Questions and Answers

Answer: D

Correct answer: Salivary amylase

Salivary amylase is a digestive enzyme: it breaks starch into sugars and has no defensive role. (Saliva does contain lysozyme, which does attack bacteria - but that is a different enzyme.) Skin is the physical barrier, mucus traps what lands on the linings, and gastric acid kills most of what is swallowed.

Answer: B

Correct answer: B-cells

Humoral immunity is antibody-mediated, and antibodies are made by B cells - specifically by the plasma cells that B cells become once activated. The name comes from “humour”, the old word for a body fluid, because the protection resides in the blood and lymph rather than in the cells themselves.

Answer: D

Correct answer: Both (b) and (c)

Innate immunity is present from birth. Everything acquired during life is either active - made by the body after an infection or a vaccination - or passive, received ready-made, as an infant receives antibodies across the placenta and in milk. So both of those qualify.

Answer: A

Correct answer: Physical barrier

These are all physical (anatomical) barriers: they block or sweep away invaders mechanically. Skin is a tough keratinised sheet, hair and eyelashes catch particles, cilia in the airways drive trapped material upwards, and the linings of the gut and respiratory tract present a continuous covered surface. They are the first line of defence and belong to innate immunity.

Answer: D

Correct answer: All of the above

All three belong to innate immunity. Phagocytes engulf and digest invaders; macrophages are the long-lived tissue phagocytes and also present antigen to T cells; natural killer cells destroy virus-infected and tumour cells without needing prior exposure. None of them requires a specific receptor for the invader, which is what distinguishes innate from acquired immunity.

Answer: A

Correct answer: Innate Immunity

Innate immunity is the first line of defence: it is present from birth, acts within minutes to hours, and meets any invader in the same non-specific way. Acquired immunity is the second line - slower to start, but specific and equipped with memory.

Answer: C

Correct answer: Immunology

Immunology is the branch that studies immune systems in all organisms. Zoology studies animals, microbiology micro-organisms, and biotechnology the application of living systems.

Answer: A

Correct answer: Acquired immunity

Acquired (adaptive) immunity is what develops during life, in response to the antigens actually encountered - whether the body makes the response itself (active) or receives antibodies ready-made (passive). Both of those are subdivisions of it, which is why the general term is the answer here.

Answer: A

Correct answer: Five

There are five classes of antibody, distinguished by their heavy chains: IgG, the commonest, and the only one crossing the placenta; IgM, a pentamer made first in a new response; IgA, which guards mucosal surfaces and appears in milk; IgE, involved in allergy and in defence against parasites; and IgD, a receptor on naive B cells.

Answer: B

Correct answer: T cells

T cells carry cell-mediated immunity, killing infected cells directly and orchestrating the rest of the response. Mast cells belong to the inflammatory and allergic response; thrombocytes are platelets, for clotting; and leukaemia is a disease, not a cell type.