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 33 questions on this lesson, each with an explanation.
An antiserum is usually taken in order to provide:
Correct answer: (B) Rapid treatment
Explanation: An antiserum contains ready-made antibodies that act quickly, so it is taken for rapid treatment, not for prevention.
The enzyme found in tears and saliva that kills bacteria is called:
Correct answer: (C) Lysozyme
Explanation: Lysozyme is an enzyme in tears and saliva that breaks down bacterial cell walls and kills them; it is part of the first line of defense.
The acid in the stomach that kills most of the microbes entering with food is:
Correct answer: (C) Hydrochloric acid
Explanation: Gastric juice contains hydrochloric acid, which kills most of the microbes that enter with food.
The protein secreted by virus-infected cells to protect neighboring cells is called:
Correct answer: (C) Interferon
Explanation: Interferon is a protein secreted by a virus-infected cell to alert neighboring cells and prevent the virus from multiplying in them.
The transfer of antibodies from the mother to the fetus through the placenta is an example of immunity that is:
Correct answer: (D) Natural passive
Explanation: The fetus receives ready-made antibodies from its mother through the placenta without producing them, so this is natural passive immunity.
The foreign substance that enters the body and stimulates it to form antibodies is called:
Correct answer: (A) The antigen
Explanation: An antigen is a foreign substance, often a protein on the surface of a microbe, that stimulates the immune system to form antibodies.
The main difference between a vaccine and an antiserum is that a vaccine:
Correct answer: (B) Makes the body produce its own antibodies
Explanation: A vaccine contains killed or weakened microbes that stimulate the body to make its own antibodies, whereas an antiserum contains ready-made antibodies.
Why does a vaccine contain killed or weakened microbes instead of the virulent microbe?
Correct answer: (B) To stimulate the body to build immunity without causing the disease
Explanation: The weakened or killed microbe stimulates the immune system to form antibodies and memory cells without causing the disease itself.
If the skin is wounded and bacteria enter the body, which line of defense confronts them next, right away?
Correct answer: (B) The second line of defense, through phagocytosis and inflammation
Explanation: When the skin, the first line of defense, is breached, the second line of defense confronts any microbe that entered, through phagocytosis and inflammation, and it is also non-specific.
Four people: (1) receives a tetanus toxoid vaccine; (2) is a breast-fed infant; (3) has recovered from mumps; (4) receives antivenom after a snake bite. Which of them formed memory cells against the antigen involved?
Correct answer: (A) Persons 1 and 3 only
Explanation: Memory cells form only in active immunity, when the person's own immune system meets the antigen: by vaccine (artificial active) or by infection (natural active). Antibodies from milk and from antivenom are ready-made, so they give passive immunity without memory cells.
The first 10 questions in every subject are free, each with an explanation.