Immune System MCQ Quiz - Objective Question with Answer for Immune System - Download Free PDF

The correct answer is Phytohemagglutinin

Explanation:

• Phytohemagglutinin (PHA) is a plant-derived lectin primarily extracted from beans, especially red kidney beans (Phaseolus vulgaris). It is known to stimulate lymphocytes, particularly T-lymphocytes, in laboratory settings, making it a potent mitogen for studying immune responses.
• PHA binds to carbohydrates on the surface of lymphocytes, triggering cell division (mitosis) and immune activation. This property is used extensively in immunological research and diagnostic applications.

Other Options:

• Complement: Complement refers to a group of proteins in the immune system that enhances (or "complements") the ability of antibodies and phagocytic cells to clear pathogens from the body. While the complement system is crucial for immune defense, it does not act as a potent antigen or mitogen for lymphocytes.
• Interleukin-1: Interleukin-1 (IL-1) is a cytokine produced by activated macrophages and is involved in the regulation of immune and inflammatory responses. Although IL-1 plays an essential role in modulating immune reactions, it does not directly act as a mitogen for lymphocytes.
• Endotoxin: Endotoxins are lipopolysaccharides derived from the outer membrane of Gram-negative bacteria. They trigger an immune response and can lead to inflammation, but they are not specific stimulators of lymphocyte mitosis or activation. Endotoxins act more broadly and are associated with systemic effects like fever and septic shock rather than direct lymphocyte activation.

The correct answer is A strategy of parasites to evade a host's immune response for their survival probability

Explanation:

• Immunological evasion refers to the ability of pathogens (including parasites, bacteria, viruses, and fungi) to avoid or suppress the host's immune system to ensure their survival and replication.
• The immune system is the body's defense mechanism designed to identify and eliminate foreign invaders, but some pathogens have evolved strategies to "evade" this defense.
• Parasites and other pathogens employ complex mechanisms to evade immune responses, ensuring their survival in the host. This process often contributes to prolonged infections, chronic diseases, or host damage.

Pathogens use various strategies, including:

• Antigenic variation: Pathogens frequently change the proteins on their surface (antigens) to avoid being recognized by the host's immune system.
• Immune suppression: Some pathogens produce molecules that suppress the immune response, reducing the ability of the host to fight back effectively.
• Camouflage: Some pathogens mimic host molecules to escape detection by the immune system.
• Intracellular hiding: Certain pathogens hide inside host cells to avoid immune detection.
• Examples:
  • Plasmodium (causative agent of malaria) uses antigenic variation to evade the immune system.
  • HIV suppresses immune cells, including T-helper cells, to avoid detection and destruction.

The correct answer is C, D, E only

Concept:

• Lymphoid organs are the organs where the origin and/or maturation and proliferation of lymphocytes occur.
• The primary lymphoid organs are bone marrow and thymus, where immature lymphocytes differentiate into antigen-sensitive lymphocytes.
• After maturation, the lymphocytes migrate to secondary lymphoid organs like the spleen, lymph nodes, tonsils, Peyer’s patches of small intestine, and appendix.
• The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells.

Explanation:

• Spleen (C): The spleen filters blood and is a site where lymphocytes interact with blood-borne antigens. It plays a crucial role in immune responses to pathogens circulating in the bloodstream.
• Lymph Nodes (D): Lymph nodes are distributed throughout the body and filter lymph. They trap antigens from lymphatic fluid and allow interaction between lymphocytes and antigens, activating adaptive immune responses.
• Peyer’s Patches (E): Peyer’s patches are specialized mucosa-associated lymphoid tissues in the small intestine. They monitor intestinal contents for antigens and are essential for immune responses in the gut-associated lymphoid tissue (GALT).

Incorrect Options:

• Thymus (A): The thymus is a primary lymphoid organ responsible for the maturation of T cells. 
• Bone Marrow (B): The bone marrow is another primary lymphoid organ responsible for the development and maturation of B cells.

The correct answer is All of the above.

Key Points

• Louis Pasteur created the first vaccines for Rabies, Cholera, and Anthrax.
• His work laid the foundation for the field of microbiology and immunology.
• The Rabies vaccine was developed in 1885 and was a major breakthrough in medical science.
• Pasteur's discoveries demonstrated the germ theory of disease and led to the development of techniques like pasteurization.

Important Points

• Rabies Vaccine: Louis Pasteur successfully treated a boy named Joseph Meister who had been bitten by a rabid dog, using the first rabies vaccine.
• Cholera Vaccine: Pasteur developed the first vaccine for chicken cholera, an important step in understanding vaccines for bacterial diseases.
• Anthrax Vaccine: He created a vaccine for anthrax to protect livestock, demonstrating the effectiveness of vaccination in preventing bacterial infections.
• These discoveries proved that diseases could be prevented through vaccination, saving millions of lives globally.

Additional Information

• Rabies: Rabies is a viral disease that causes inflammation of the brain in humans and animals. It is usually transmitted through the bite of an infected animal.
• Cholera: Cholera is an infectious disease caused by the bacterium Vibrio cholerae. It spreads through contaminated water and food, leading to severe diarrhea and dehydration.
• Anthrax: Anthrax is a bacterial infection caused by Bacillus anthracis. It affects both humans and animals and is often transmitted through spores from infected animals or animal products.
• Germ Theory of Disease: Louis Pasteur's germ theory postulated that microorganisms were the cause of many diseases. This theory revolutionized medicine and led to hygiene practices that reduced the spread of disease.
• Pasteurization: A process developed by Pasteur to kill harmful bacteria in food and drinks (like milk) through controlled heating, making them safe for consumption.

The correct answer is Only (i).

Key Points

• Covaxin is India's indigenous Covid-19 vaccine developed by Bharat Biotech.
• It is an inactivated vaccine developed using Whole-Virion Inactivated Vero Cell technology.
• Covaxin has been approved for emergency use in India and several other countries.
• It was developed in collaboration with the Indian Council of Medical Research (ICMR) and the National Institute of Virology (NIV).

Important Points

• Covaxin has shown efficacy against Covid-19 variants, including Delta, according to clinical studies.
• It requires two doses administered 28 days apart for full efficacy.
• Bharat Biotech has also worked on expanding production facilities to meet demand.

Additional Information

• Option (ii): Covaxin is not an intranasal vaccine. Intranasal vaccines are administered through the nose, and Bharat Biotech has developed a separate intranasal vaccine called iNCOVACC.
• Option (iii): Covaxin is not developed by Serum Institute of India. The Serum Institute is responsible for producing Covishield, another Covid-19 vaccine developed by AstraZeneca and Oxford University.
• Intranasal Vaccines: These types of vaccines are designed to be administered through the nasal route and are considered beneficial for their ease of administration and ability to induce mucosal immunity.
• Serum Institute of India: A leading vaccine manufacturer based in Pune, India, known for producing Covishield, which has been widely used for Covid-19 immunization globally.

The correct answer is Passive immunization.

• If a person is infected with some deadly microbes to which quick immune response is required, we need to directly inject the preformed antibodies. This type of immunization is known as Passive immunization.
• Passive immunity: When ready-made antibodies are directly given to protect the body against foreign agents, it is called passive immunity.
• Active immunity: When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called active immunity.

Active vs passive immunity

The correct answer is Proteins.

Key Points

•  Amino acids are biologically important organic compounds.
• A large proportion of our cells, muscles and tissue is made up of amino acids.
• Amino acids play central roles both as building blocks of proteins and as intermediates in metabolism.

​Carbohydrates:

• These are organic compounds of carbon, hydrogen, and oxygen. These are widely distributed in plants and food containing carbohydrates are called energy foods.
• Carbohydrates are broadly classified as :
  • Simple carbohydrates 
    • Monosaccharides
    • Disaccharides
  • Complex carbohydrates
    • Polysaccharides

Concept:

• Cytokines are low molecular proteinaceous chemical messengers that are secreted by the cells of the immunity system in response to stimuli.
• These are secreted by WBCs and various other cells of the body.
• They serve as messengers of the immune system.
• Cytokines bind to specific receptors on the target cells.
• Once bound they induce signal transduction that results in triggering gene expression in the target cell.
• Depending on the type of cell that secretes cytokines, they are of following types:
  1. Lymphokines: Secreted by lymphocytes. These are secreted specifically by T cells. (Functions similar to those mentioned above for cytokines).
  2. Monokines: Secreted by monocytes and macrophages.
  3. Interleukins: Secreted by some leukocytes and act on other leukocytes.
• Apart from this, chemokines are also a special type of cytokine that plays an important role in inflammation.

Important Points

• There are several kinds of lymphokines. 
• Some of these are interferons, granulocyte-macrophage colony-stimulating factors, migration inhibitory factors and lymphotoxin.
• Out of the options given in the question, the most common lymphokine is interferon.

Interferon - 

• Interferons (IFN) are produced in response to an infection caused by a virus.
• These are proteins that are known to interfere with viral replication.
• There are mainly three types of interferons - IFN-α, IFN-ß and IFN-γ.
• Interferons trigger the synthesis of host cell proteins that in turn inhibit viral regulation.
• It increases the expression of the Major Histocompatibility Complex (MHC).
• It also causes the activation of natural killer cells.

 ​

Hence, the correct answer is option 4 (Interferon).

Concept:

• The immunity system provides the body the ability to fight against the different pathogenic organisms or the toxins that damage the tissues and organs.
• The immunity system consists of several structurally and functionally different organs and tissues.
• The organs of the immune system are divided into two groups - Primary lymphoid organs (E.g.: Bone marrow) and Secondary lymphoid organs (E.g.: Tonsils).
• Lymphocytes are the white blood cells that play an important role in the immune system.

Important Points

CLONAL SELECTION:

• Lymphocytes are of two types - B cells and T cells.
• B cells produce antibodies.  Antibodies are the chemicals produced by the immune system in response to the antigenic stimulus. They fight against the antigens or the toxins and neutralize them.
• T cells on the other hand fight against invading pathogens.
• The B cells during differentiation in the bone marrow, is genetically programmed to produce antibodies.
• The antibodies have a unique antigen-binding site.
• These sites known as paratopes are present in the variable region of the heavy and light chains of the immunoglobulin.
• These regions are characterized by an amino acid sequence that varies from one immunoglobulin to other.
• The antigen-binding site is made through a series of gene translocations. These function as B cell receptors.
• During a pathogen attack, antigens come across the cells of the immune system.
• The epitope (site at which antibody binds) present on the antigen will react with only those B-cells that have receptors that fit more or less.
• This in turn activates the B-cells.
• This process is known as clonal selection.
• The B cells thus activated start proliferating rapidly under the influence of cytokines produced by the effector T cells.
• As a result, a large number of clones of the activated B cells are produced.
• All these are the clones of the activated B-cells that have the correct specificity to the antigen.
• This is known as clonal expansion.​
• Based on the above-given information, the only option that correctly explains the clonal selection, as well as the clonal expansion process is the proliferation and differentiation of lymphocytes that occur in response to a specific antigen.

So the correct answer is option 2.

Concept:

• The ability of the human body to fight against the different pathogenic organisms or the toxins that they release that damage the tissues and organs are called immunity.
• The system that provides this immunity to fight against pathogens is called the immunity system.
• Antigens -
  • These are the foreign substances (pathogenic organisms or toxins) that invade the body and are capable of eliciting an immune response.
• Antibodies -
  • These are the chemicals produced by the immune system in response to the antigenic stimulus in the body.
  • They are also called immunoglobulins (Ig).
  • They fight against the antigens or the toxins and neutralize them.

Explanation:

Option 1 - INCORRECT

• ​The region of an antibody that binds with an antigen is known as a paratope.
• It is present in the variable region of the heavy and light chains of the immunoglobulin.
• These regions are characterized by an amino acid sequence that varies from one immunoglobulin to other and is associated with antigen-binding sites.
• Most antibodies carry two antigen-binding sites.

Option 2 - CORRECT

• ​Antigens are foreign bodies that when introduced into the body of an organism elicits an immune response and stimulate the production of antibodies.
• Most antigens are proteinaceous in nature. Some antigens may also be made up of carbohydrates.
• Epitopes or antigenic determinants are present on an antigen.
• These are the sites on antigens that are recognized by antibodies and receptors present on T and B cells.

 ​

Option 3 - INCORRECT

• ​Each antibody molecule is made up of four polypeptide chains.
• There are two long chains called Heavy chains or 'H' chains.
• The other two are short chains known as Light chains or 'L' chains.
• Heavy chains of an Ig help the antibody to be expressed on the surface of B cells due to its transmembrane domain.
• The variable region of the heavy chain contains the antigen binding site - paratope.

Option 4 - INCORRECT

• The ​V-region of the light chain of an antibody refers to the variable region of an antibody.
• It is present on both the heavy and light chains of Ig.
• It is associated with antigen-binding sites called paratopes. 
• Paratopes are the sites where an antibody binds with an antigen during the formation of an antigen-antibody complex.

So the correct answer is option 2.

Concept:

• Certain drugs are commonly abused for recreational purposes.
• These drugs include opioids, cannabinoids and coca alkaloids.
• They might be obtained from flowering plants or even some fungi.
• Drugs like barbiturates, amphetamines, benzodiazepines and LSDs that have medicinal usage for some patients, are also sometimes abused for recreational purposes.

Explanation:

 Option (1): Latex of Papaver somniferum

• It is the source of opioids like heroin, also known as 'smack'.
• The dried latex of unripe flower pods of poppy plants are used for this purpose.
• Hence, this option is CORRECT.

Option (2): Leaves of Cannabis sativa

• It is the source of cannabinoids like marijuana and ganja which affects the cardiovascular system.
• These drugs are abused by oral ingestion or inhalation.
• Hence, this option is INCORRECT.

Option (3): Flowers of Datura

• It is the source of hallucinogens like atropine and scopolamine.
• Hence, this option is INCORRECT.

Option (4 ): Fruits of Erythroxylum coca

• It is the source of cocaine which causes hallucinations and euphoria.
• Cocaine is commonly also called as 'crack' or 'coke'.
• Hence, this option is INCORRECT.

Hence, the correct answer is option (1).

Additional Information

Other features of 'smack' - 

• Chemical Name - Diacetylmorphine or diamorphine.
• Pharmacological uses - It is used as an analgesic in extreme pain management for myocardial infarction, severe trauma, post-surgical pain and terminal illnesses like cancer.
• Action mechanism - It binds to the receptors in central nervous system (CNS) and the gastrointestinal tract.
• Physiological effects - It acts as a depressant and is known to slow down body processes, causing drowsiness, euphoria and sense of detachment.
• Mode of usage - It is abused by snorting or injections.

The correct answer is option 2

Key Points

• Live attenuated bacterial vaccines are vaccines that contain weakened or live bacteria that can cause disease.
• These vaccines are designed to stimulate the body's immune system to produce antibodies against the bacteria, without causing the actual disease.
• The typhoid vaccine is an example of a live attenuated bacterial vaccine. It is made from a weakened strain of Salmonella typhi, the bacterium that causes typhoid fever. The vaccine is given orally, and it is about 80% effective in preventing typhoid fever.Hence option 2 is correct.
• Anthrax is caused by Bacillus anthracis, which is a spore-forming bacteria.
  • Anthrax vaccines are made from killed bacteria or from the bacteria's toxins.
• Plague is caused by Yersinia pestis, which is a bacterium.
• Plague vaccines are made from killed bacteria.

The correct answer is Phytohemagglutinin

Explanation:

• Phytohemagglutinin (PHA) is a plant-derived lectin primarily extracted from beans, especially red kidney beans (Phaseolus vulgaris). It is known to stimulate lymphocytes, particularly T-lymphocytes, in laboratory settings, making it a potent mitogen for studying immune responses.
• PHA binds to carbohydrates on the surface of lymphocytes, triggering cell division (mitosis) and immune activation. This property is used extensively in immunological research and diagnostic applications.

Other Options:

• Complement: Complement refers to a group of proteins in the immune system that enhances (or "complements") the ability of antibodies and phagocytic cells to clear pathogens from the body. While the complement system is crucial for immune defense, it does not act as a potent antigen or mitogen for lymphocytes.
• Interleukin-1: Interleukin-1 (IL-1) is a cytokine produced by activated macrophages and is involved in the regulation of immune and inflammatory responses. Although IL-1 plays an essential role in modulating immune reactions, it does not directly act as a mitogen for lymphocytes.
• Endotoxin: Endotoxins are lipopolysaccharides derived from the outer membrane of Gram-negative bacteria. They trigger an immune response and can lead to inflammation, but they are not specific stimulators of lymphocyte mitosis or activation. Endotoxins act more broadly and are associated with systemic effects like fever and septic shock rather than direct lymphocyte activation.

The correct answer is A strategy of parasites to evade a host's immune response for their survival probability

Explanation:

• Immunological evasion refers to the ability of pathogens (including parasites, bacteria, viruses, and fungi) to avoid or suppress the host's immune system to ensure their survival and replication.
• The immune system is the body's defense mechanism designed to identify and eliminate foreign invaders, but some pathogens have evolved strategies to "evade" this defense.
• Parasites and other pathogens employ complex mechanisms to evade immune responses, ensuring their survival in the host. This process often contributes to prolonged infections, chronic diseases, or host damage.

Pathogens use various strategies, including:

• Antigenic variation: Pathogens frequently change the proteins on their surface (antigens) to avoid being recognized by the host's immune system.
• Immune suppression: Some pathogens produce molecules that suppress the immune response, reducing the ability of the host to fight back effectively.
• Camouflage: Some pathogens mimic host molecules to escape detection by the immune system.
• Intracellular hiding: Certain pathogens hide inside host cells to avoid immune detection.
• Examples:
  • Plasmodium (causative agent of malaria) uses antigenic variation to evade the immune system.
  • HIV suppresses immune cells, including T-helper cells, to avoid detection and destruction.

The correct answer is C, D, E only

Concept:

• Lymphoid organs are the organs where the origin and/or maturation and proliferation of lymphocytes occur.
• The primary lymphoid organs are bone marrow and thymus, where immature lymphocytes differentiate into antigen-sensitive lymphocytes.
• After maturation, the lymphocytes migrate to secondary lymphoid organs like the spleen, lymph nodes, tonsils, Peyer’s patches of small intestine, and appendix.
• The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells.

Explanation:

• Spleen (C): The spleen filters blood and is a site where lymphocytes interact with blood-borne antigens. It plays a crucial role in immune responses to pathogens circulating in the bloodstream.
• Lymph Nodes (D): Lymph nodes are distributed throughout the body and filter lymph. They trap antigens from lymphatic fluid and allow interaction between lymphocytes and antigens, activating adaptive immune responses.
• Peyer’s Patches (E): Peyer’s patches are specialized mucosa-associated lymphoid tissues in the small intestine. They monitor intestinal contents for antigens and are essential for immune responses in the gut-associated lymphoid tissue (GALT).

Incorrect Options:

• Thymus (A): The thymus is a primary lymphoid organ responsible for the maturation of T cells. 
• Bone Marrow (B): The bone marrow is another primary lymphoid organ responsible for the development and maturation of B cells.