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GATE 2019 BT Q.10: solution and answer

GATE 2019 · BTQ.10 · 1 mark · MCQ

Which one of the following is NOT a part of the human nonspecific defense system?

  1. (A)

    Interferon

  2. (B)

    Mucous

  3. (C)

    Saliva

  4. (D)

    Antibody

See the question in the paper
GATE 2019 BT question 10Tap to open full size

Answer and solution

ANSWER

The answer is (D) Antibody, which belongs to the specific (adaptive) immune response.

Official answer: DSource: Official answer key, GATE 2019 BT (IIT Madras)

  1. Nonspecific (innate) defence acts the same way against any pathogen and needs no prior exposure. It includes physical and chemical barriers, phagocytes, natural killer cells, inflammation and interferons.

  2. (A) Interferon: antiviral proteins released by infected cells that put neighbouring cells into an antiviral state against any virus. This is innate, so it is part of the nonspecific system.

  3. (B) Mucous: mucus membranes trap microbes and carry them away by ciliary action. This is a physical barrier, so it is nonspecific.

  4. (C) Saliva: it contains lysozyme, which breaks down bacterial peptidoglycan, and it washes microbes away. This is a chemical barrier, so it is nonspecific.

  5. (D) Antibody: immunoglobulins are made by plasma cells (activated B cells) and bind one particular antigen. This is the adaptive, specific response, so it is NOT part of the nonspecific system.

  6. Hence the answer is (D).

KEY IDEA

Innate (nonspecific) defences work the same against any pathogen without prior exposure: barriers such as mucus and saliva, phagocytes, NK cells, inflammation and interferons. Antibodies are made against one particular antigen, so they belong to the adaptive response.

WATCH OUT FOR

Counting interferon as specific because it acts against viruses. It protects against any virus and needs no prior exposure, so it is innate. Antibodies are the only option that recognises one particular antigen.

From the GATE 2019 BT paper. Every question of this paper · Download the full paper · All 6 Immune system questions, with notes

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