This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “The Immune Response”.
1. What is not required in the innate immune responses?
b) strong immunity
d) previous contact
Explanation: In innate immune responses, prior encounter with the microbe is not required. The innate immune responses provide the body with first line of defense. The other type of immunity is acquired immunity.
2. Which of the following group of pathogens always reside intracellularly in the host?
Explanation: The viruses (both DNA and RNA) always reside inside the host cell and hence can be classified as intracellular pathogens. Others such as bacteria can be intracellular or extracellular.
3. The phagocytes can recognize pathogens by means of _____________________
a) necrosis factor
b) complement activation
c) pattern recognition receptors
d) adhesion molecules
Explanation: The pathogens make their initial contact with phagocytic cells (dendrites and macrophages) which possess pattern recognition receptors (PRRs). The PRRs can recognize the highly conserved macromolecules in bacteria and viruses.
4. Which of the following proteins in fruit fly play the major function of dorsoventral polarity of the fly embryo?
d) Linker DNA
Explanation: The protein Toll, present in the fruit fly, plays a dual role of promoting dorsoventral development of the embryo and providing the fly with immunity against pathogens.
5. Which of the following drug acts by stimulating toll-like receptors (TLRs)?
Explanation: Aldara was approved in 1997 and works by stimulating the toll-like receptors – transmembrane proteins present on membranes of different cells. The drug is prescribed for a number of skin infections.
6. Innate immune responses are accompanied by inflammation.
Explanation: Innate immune responses are usually accompanied by inflammation at the site of infection. At this site certain cells and plasma proteins leave the blood vessels and enter the affected tissues.
7. Which of the following is an antimicrobial peptide synthesized by lymphocytes?
Explanation: 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.
8. Which type of immune cells are responsible for eradicating intracellular pathogens?
a) natural killer cells
b) mast cells
d) specific lymphocytes
Explanation: Natural killer cells are components of innate immunity that act by killing the cells infected by intracellular pathogens. The natural killer (NK) cells induce the infected cells to undergo apoptosis.
9. Which type of interferons is associated with an antiviral innate response?
a) Type I
b) Type II
c) Type III
d) Type IV
Explanation: 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.
10. Adaptive immune responses are more specific that innate immune responses.
Explanation: 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.
11. Humoral immunity is mediated by ______________
a) mast cells
Explanation: Humoral immunity is the falls under the adaptive immune response and is mediated by the antibody-secreting B-lymphocytes. The antibodies are globular, blood-borne proteins of the immunoglobulin superfamily.
12. B and T lymphocytes arise from _____________
a) hematopoietic stem cells
b) germ cells
c) somatic cells
Explanation: B and T cells arise from the same precursor – hematopoietic stem cells that undergo different pathways of differentiation. B-lymphocytes target the extracellular pathogens whereas the T-lymphocytes attack intracellular pathogens.
13. A rare disease congenital agammaglobulinemia is caused due to abnormality in __________________
a) humoral antibody
b) cell-mediated immunity
c) acidic/alkaline pH
Explanation: Humoral antibody deficiency can lead to a rare a disease – congenital agammaglobulinemia wherein the cell-mediated immunity is normal. It is an immunodeficiency disease that is extremely rare.
Sanfoundry Global Education & Learning Series – Cell Biology.
To practice all areas of Cell Biology, here is complete set of 1000+ Multiple Choice Questions and Answers.