MCQ on Immunology with Detailed Explanation

Ans: (c) Immunology

Explanation: The study of the immune system and the cell-mediated and humeral aspects of the immunity and the immune responses are defined as immunology. It is a very important branch of the medical and biological sciences. Immunology charts, measures and contextualizes the physiological functioning of the immune system in state of both health and diseases.

Ans: (c) Immunity

Explanation: our body fights against harmful viruses and pathogens every day and help us to stay safe from diseases. Consequently, Immunity is defined as the ability of an organism to fight against diseases and infections with the help of the immune system. Immunity is further divided into two categories, innate immunity and adaptive immunity.

Ans: (b) Immune system

Explanation: The immune system functions as a physical barrier to prevent the entry of disease-causing pathogens such as bacteria, viruses, parasites as well as cancer cells, while protecting healthy tissue. The Immune system of our body is created with human’s body cells and proteins. The Immunity system retains the virus history with whom it fights so that if the same type of virus attacks, then the system can kill the virus.

Ans: (a) Acquired immunity

Explanation: Acquired immunity is immunity you develop over your lifetime. It is not present at birth, it is learned. Although you are born with all the cells of your immune system, it gets stronger throughout your life as you expose your body to more germs. It is called acquired or adaptive immunity. It can come from a vaccine, exposure to an infection or disease or another person’s antibodies.

Ans: (a) True

Explanation: All organisms possess some disease resistance ability that they have inherited from their parents or have gained naturally; this is known as innate immunity. It is the defense system with which you were born. It provides you with the first line of defense against all antigens.

However, it does not have any immunological memory, which means it cannot remember antigens. Therefore, it initiates the same level of response every time it encounters the same antigen and viruses.

Ans: (b) Antigen no-specific

Explanation: Adaptive immunity only provides immunity against a specific type of antigen, unlike innate immunity which is antigen non-specific and can protect against any antigen. The specificity of the adaptive immune system occurs because it synthesizes millions of different T cell populations, each expressing a TCR that differs in its variable domain.

Ans: (b) T cells

Explanation: Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages and NK-cells, the production of antigen-specific cytotoxic T-lymphocytes and the release of various cytokines in response to an antigen.

As shown in the figure, T helper (Th) cells recognize infected cells with the help of specialized antigen-presenting cells. After recognition, Th cells release cytokines and chemokines, and they orchestrate a series of reactions involving cytolytic T cells, macrophages and NK cells. These cells move to the site of infection and phagocytose infected cells and destroy them.

Ans: (a) Five

Explanation: An antibody, also known as immunoglobulin, is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. There are five types of antibodies and they are classified into IgG, IgM, IgA, IgD and IgE. They are distributed and function differently in the body.

Ans: (d) IgE

Explanation: IgE participates in hypersensitivity reactions and involves IgE mediated release of antibodies, but not present in tears. Tears are secretions of lacrimal gland and also known as lacrimal fluid consisting of Lysozyme, Lactoferin and IgA. Lysozyme fights against bacterial infection as a part of the immune system.

Ans: (b) IgM

Explanation: The first class of antibody which provides a primary immune response is IgM followed by IgG. The primary immune response is characterized by the appearance of neutralizing antibodies of the IgM class between days four and seven. When the same antigens attack again, the secondary immune response is generated which is provided by IgG.

Ans: (d) IgM is primarily restricted in the circulation

Explanation: IgM is the first immunoglobulin developed during human fetal development at 20 weeks. Unlike IgG (responsible for circulation) antibody which provides passive immunity to the fetus, IgM antibody is restricted from crossing the placenta due to its size. It is also the first antibody to respond during infection.

Ans: (d) Reproduce only by binary fission

Explanation: Antigens are molecules that trigger the production of antibodies by inducing an immune response. A good antigen is defined by its complexity and size, plus its foreignness and dosage. Complex molecules are usually good antigens. Large size and highly complex antigen are considered as good and more responsive.

Ans: (d) Recombinant vaccine

Explanation: Hepatitis B vaccine is a highly effective and safe vaccine which is produced by recombinant DNA technology. Hep-B is a noninfectious recombinant DNA vaccine containing highly purified hepatitis B surface antigen (HBsAg). It is produced from the fermentation of genetically engineered yeast, Saccharomyces cerevisiae. It is indicated for prevention of infection caused by all known subtypes of hepatitis B virus.

Ans: (a) Interferons

Explanation: monokines, lymphokines and interferons are cytokines which are of low molecular weight soluble protein or glycoprotein. Interferon is cytokines produced by cells in response to virus infections. Interferons are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus infected cell will release interferons causing nearby cells to heighten their antiviral defenses.

Ans: (a) Cytokine barriers

Explanation: cytokine inhibits viral replication. They form an innate immune system. A cytokine barrier includes interferon, a type of protein secreted b y virus-infected cells which protects the non-infected cells from further vital infections. Cytokine barriers are a form of innate immunity that plays an important role in preventing viral replication and responds to many types of antigens.

Ans: (b) Toll-like receptor

Explanation: Toll-like receptors are a class of proteins that play a key role in the innate immune system. It functions exclusively as a signaling receptor and is a pattern recognition molecule. It was identified as a protein involved in the formation of dorso-ventral polarity in developing fly embryos.

Ans: (d) Basophil

Explanation: Phagocytosis is a process wherein a cell binds to the item it wants to engulf on the cell surface and draws the item inward while engulfing around it. The process of phagocytosis often happens when the cell is trying to destroy something, like a virus or an infected cell.

Macrophages, neutrophils, monocytes, dendritic cells, osteoclasts and eosinophils are cells involved in phagocytosis. However, basophils that represent less than 0.5% of leukocytes in the peripheral blood of humans do not possess phagocytic activity. Basophils contain anticoagulant heparin, which prevents blood from clotting too quickly.

Ans: (c) Neutrophils

Explanation: Neutrophils are the first to arrive in large numbers at the site of infection, with monocytes and immature dendritic cells being recruited later because there are so many of them in circulation at any given time. Neutrophils are the second major type of phagocytic cell which is found in abundance in blood and has a short life span.

Ans: (c) Macrophage

Explanation: Monocytes are a type of leukocyte or white blood cell. Although they share some similar physiological capacities as neutrophils, monocytes retain a proliferative capacity and can differentiate into resident phagocytic cells, broadly termed macrophages. They are the largest type of leukocytes and can differentiate into macrophages and conventional dendritic cells. Macrophages are specialized cells involved in the detection, phagocytosis and destruction of bacteria and other harmful organisms.

Ans: (d) Kinins

Explanation: Kinins are proteins in the blood that cause inflammation and affect blood pressure (especially low blood pressure). They also increase blood flow throughout the body. Make it easier for fluids to pass through small blood vessels. Kinins are the principal mediator of inflammatory response which is present in blood plasma in an active form. It causes vasodilatation and increased permeability of capillaries.