Chapter 4 — Immunity in Living Organisms · Biology. These are 10 questions from the Magmo3 bank on this lesson, from easy to hard. Solve each one, then open "Show answer and explanation". Magmo3 has 38 questions on this lesson, each with an explanation.
Killer T cells destroy:
Correct answer: (B) Virus-infected cells and cancerous cells
Explanation: Killer T cells directly attack and kill virus-infected cells and cancerous cells.
Antibodies are mainly produced by:
Correct answer: (D) Plasma cells formed from B cells
Explanation: Plasma cells, which form from B lymphocytes, are the cells that produce and secrete antibodies.
An antibody is composed of a number of polypeptide chains equal to:
Correct answer: (A) Four chains
Explanation: An antibody is composed of four polypeptide chains: two heavy chains and two light chains.
Macrophages (large phagocytic cells) help in specific immunity by:
Correct answer: (D) Engulfing the antigen and displaying its parts to T cells
Explanation: Macrophages engulf the microbe and display parts of the antigen on their surface so that helper T cells recognize it and start the response.
Humoral immunity is more effective against microbes present in:
Correct answer: (A) Body fluids such as blood and lymph
Explanation: Antibodies act in body fluids such as blood and lymph, so humoral immunity resists microbes and toxins that are outside cells.
The secondary immune response is:
Correct answer: (D) Faster and stronger than the primary response
Explanation: The secondary response is faster and stronger because of the memory cells that formed during the primary response.
The antibody mechanism in which antibodies bind to the outer coats of viruses, preventing them from adhering to the host cell membranes and entering the cells, is called:
Correct answer: (A) Neutralization
Explanation: Neutralization: antibodies bind to the outer coats of viruses so the viruses cannot adhere to the host cell membranes, spread or pass inside them; if a virus has already attached, the antibodies keep its coat sealed so its nucleic acid cannot come out. Binding to toxins is a separate mechanism (antitoxins).
A person met antigen A on day 0. On day 30 he was exposed to antigen A again and, at the same time, to a new antigen B. Which describes the antibody levels in the following week?
Correct answer: (C) Anti-A antibodies rise faster and higher than anti-B antibodies
Explanation: Memory cells from the first exposure produce a fast, strong secondary response to antigen A. Antigen B meets no memory cells, so it causes only a slow, weak primary response.
Why do antibodies take time to appear in sufficient quantity when a new microbe first enters the body?
Correct answer: (A) Because B cells need time to recognize the antigen, multiply, and transform into plasma cells
Explanation: In the primary response there are no memory cells, so B cells need time to recognize the antigen, multiply, and transform into plasma cells, which is why it is slow.
A child is born without a thymus gland. Which immunity will be directly affected?
Correct answer: (B) Cell-mediated immunity, by T cells
Explanation: T cells mature in the thymus gland, so its absence affects the maturation of T cells and cell-mediated immunity.
The first 10 questions in every subject are free, each with an explanation.