Immune System Questions and Answers

Q: Which of the following drugs acts by stimulating toll-like receptors (TLRs)?

Correct answer: AldaraAldara is imiquimod, which stimulates TLR7 and so provokes a local release of interferon and other cytokines. It is applied to the skin for genital warts, actinic keratoses and superficial basal cell carcinoma. Doxorubicin is a cytotoxic drug, neosporin an antibiotic ointment, and vimentin a structural protein.

Q: Innate immune responses are accompanied by inflammation.

Correct answer: TrueInflammation is the innate response made visible. Damaged tissue and activated macrophages release mediators such as histamine and cytokines, which dilate the local vessels and make them leaky - producing the redness, heat, swelling and pain, and bringing plasma proteins and phagocytes to the site.

Q: Which type of immune cells are responsible for eradicating intracellular pathogens?

Correct answer: natural killer cellsNatural killer cells deal with pathogens hiding inside cells. They do not recognise the pathogen itself; they check whether a cell is displaying its normal MHC class I molecules, and kill it if it is not - which is exactly the state a virus-infected or tumour cell tends to be in. Being part of innate immunity, they act without any prior exposure.

Q: Humoral immunity is mediated by ______________

Correct answer: lymphocytesHumoral immunity depends on antibodies, and antibodies are made by B lymphocytes after they mature into plasma cells - with helper T lymphocytes, also lymphocytes, providing the signals that permit it. Mast cells and neutrophils belong to inflammation and phagocytosis; leucocyte is the general word for a white cell, of which lymphocytes are one kind.

Q: B and T lymphocytes arise from _____________

Correct answer: hematopoietic stem cellsBoth arise from the haematopoietic stem cells of the bone marrow. B cells complete their maturation there; T cells migrate to the thymus to mature, which is what the T stands for. Germ cells give rise to gametes, and have nothing to do with it.

Q: A rare disease congenital agammaglobulinemia is caused due to abnormality in __________________

Correct answer: humoral antibodyCongenital agammaglobulinaemia - Bruton’s disease - is a failure of B cells to mature, so almost no immunoglobulin is made. The defect is therefore in the humoral (antibody) arm. Cell-mediated immunity is intact, which is why such patients handle viruses reasonably well but suffer repeated bacterial infections, the very ones antibody normally controls.

Q: The protein, produced by B cells that binds to a specific antigen is

Correct answer: antibodyAn antibody (immunoglobulin) is the Y-shaped protein secreted by plasma cells, with two binding sites shaped to fit one particular antigen. Binding neutralises the antigen, marks it for phagocytosis, or triggers complement. A phagocyte and a leucocyte are cells; a vaccine is a preparation that provokes antibody rather than being one.

31.

Which of the following drugs acts by stimulating toll-like receptors (TLRs)?

A.Doxorubicin
B.Neosporin
C.Aldara
D.Vimentin

Answer: C

Correct answer: Aldara

Aldara is imiquimod, which stimulates TLR7 and so provokes a local release of interferon and other cytokines. It is applied to the skin for genital warts, actinic keratoses and superficial basal cell carcinoma. Doxorubicin is a cytotoxic drug, neosporin an antibiotic ointment, and vimentin a structural protein.

Discuss in Forum

32.

Innate immune responses are accompanied by inflammation.

A.True
B.False

Answer: A

Correct answer: True

Inflammation is the innate response made visible. Damaged tissue and activated macrophages release mediators such as histamine and cytokines, which dilate the local vessels and make them leaky - producing the redness, heat, swelling and pain, and bringing plasma proteins and phagocytes to the site.

Discuss in Forum

33.

Which of the following is an antimicrobial peptide synthesized by lymphocytes?

A.adhesins
B.condensins
C.defensins
D.complement

Answer: C

Defensins are antimicrobial peptides synthesized by the lymphocytes and epithelial cells. The defensins can bind to various pathogenic bacteria and bring about their demise. Similarly, blood also contains complement - a group of soluble proteins that carry out the destruction of pathogens.

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34.

Which type of immune cells are responsible for eradicating intracellular pathogens?

A.natural killer cells
B.mast cells
C.neurons
D.specific lymphocytes

Answer: A

Correct answer: natural killer cells

Natural killer cells deal with pathogens hiding inside cells. They do not recognise the pathogen itself; they check whether a cell is displaying its normal MHC class I molecules, and kill it if it is not - which is exactly the state a virus-infected or tumour cell tends to be in. Being part of innate immunity, they act without any prior exposure.

Discuss in Forum

35.

Which type of interferons is associated with an antiviral innate response?

A.Type I
B.Type II
C.Type III
D.Type IV

Answer: A

In a type of antiviral response initiated within the cell, type I interferons (IFN-alpha and IFN-beta) are produced and secreted into the extracellular space where they bind to noninfected cells and render them resistant to subsequent viral infections.

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36.

Adaptive immune responses are more specific that innate immune responses.

A.True
B.False

Answer: A

Acquired (or adaptive) immune systems are more specific than the innate immune responses and can distinguish between two very similar molecules. The adaptive immune responses possess a memory i.e. an individual cannot develop the same disease twice.

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37.

Humoral immunity is mediated by ______________

A.mast cells
B.neutrophils
C.lymphocytes
D.leukocytes

Answer: C

Correct answer: lymphocytes

Humoral immunity depends on antibodies, and antibodies are made by B lymphocytes after they mature into plasma cells - with helper T lymphocytes, also lymphocytes, providing the signals that permit it. Mast cells and neutrophils belong to inflammation and phagocytosis; leucocyte is the general word for a white cell, of which lymphocytes are one kind.

Discuss in Forum

38.

B and T lymphocytes arise from _____________

A.hematopoietic stem cells
B.germ cells
C.somatic cells
D.spermatocytes

Answer: A

Correct answer: hematopoietic stem cells

Both arise from the haematopoietic stem cells of the bone marrow. B cells complete their maturation there; T cells migrate to the thymus to mature, which is what the T stands for. Germ cells give rise to gametes, and have nothing to do with it.

Discuss in Forum

39.

A rare disease congenital agammaglobulinemia is caused due to abnormality in __________________

A.humoral antibody
B.cell-mediated immunity
C.acidic/alkaline pH
D.homeostasis

Answer: A

Correct answer: humoral antibody

Congenital agammaglobulinaemia - Bruton’s disease - is a failure of B cells to mature, so almost no immunoglobulin is made. The defect is therefore in the humoral (antibody) arm. Cell-mediated immunity is intact, which is why such patients handle viruses reasonably well but suffer repeated bacterial infections, the very ones antibody normally controls.

Discuss in Forum

40.

The protein, produced by B cells that binds to a specific antigen is

A.phagocyte
B.leukocyte
C.vaccine
D.antibody

Answer: D

Correct answer: antibody

An antibody (immunoglobulin) is the Y-shaped protein secreted by plasma cells, with two binding sites shaped to fit one particular antigen. Binding neutralises the antigen, marks it for phagocytosis, or triggers complement. A phagocyte and a leucocyte are cells; a vaccine is a preparation that provokes antibody rather than being one.

Discuss in Forum

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