Immunity MCQs with Answers
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
The ability of the body to resist damage from foreign substances like microorganisms and harmful chemicals is defined as:
Immunity is specifically defined as the ability to resist damage from foreign substances such as microorganisms and harmful chemicals.
The body's response to foreign molecules, characterized by the production of antibodies against a specific antigen, is known as:
An immune response is the body's reaction to foreign molecules, including the production of antibodies against a specific antigen.
The term "immune" is derived from:
Word immune is derived from The Latin word "immunis" that means "safe" or "free of burden."
Which Greek historian observed that individuals who recovered from a disease often became resistant to subsequent infections of the same disease?
Thucydides, a Greek historian, observed this phenomenon more than 2000 years ago.
The English country doctor who hypothesized that cowpox conferred protection against smallpox in 1796 was:
Edward Jenner hypothesized this protective effect of cowpox against smallpox in 1796.
Which of the following is considered the first line of defense against microbial attack in the human body?
The first line of defense consists of external barriers that prevent microbes from entering the body.
These two serve as the first line of defense:
The skin and the mucous membranes of the digestive and respiratory tracts are the two main external barriers.
The two primary layers that make up the human skin are:
The skin is composed of two layers: the dermis and the epidermis.
Which layer of the skin is described as dense, irregular connective tissue containing nerve endings, hair follicles, glands, and lymphatics?
The dermis is characterized by dense, irregular connective tissue with various embedded structures.
The most abundant cells in the epidermis, responsible for producing keratin, are called:
Keratinocytes are the primary cells of the epidermis and produce keratin.
Which cells in the epidermis contribute to skin color?
Melanocytes are responsible for skin pigmentation.
The sebaceous glands are located in:
The sebaceous glands, located in the dermis, produce an oily, white substance rich in lipids called sebum, which oils the hair and skin surface.
The secretions from sweat glands and sebaceous glands contribute to the skin's defense by containing:
These secretions, such as lactic acid, inhibit the growth of bacteria and fungi.
In the stomach, hydrochloric acid is secreted by which cells to kill microorganisms?
Oxyntic or parietal cells in the stomach are responsible for secreting hydrochloric acid.
What is the primary function of the hairs lining the vestibule of the nasal cavity?
Hairs in the nasal vestibule serve to trap large particles of dust from the inhaled air.
The mucous membrane lining the nasal cavity consists of pseudostratified ciliated columnar epithelium with what type of cells that secrete mucus?
Goblet cells in the nasal mucous membrane secrete mucus to trap debris.
How are trapped debris and mucus swept posteriorly from the nasal cavity to the pharynx for elimination?
Cilia on the surface of the mucous membrane sweep mucus and trapped debris towards the pharynx.
What is the approximate maximum diameter of particles that typically do NOT enter the lungs through the nose due to the nasal turbulence mechanism?
The nasal turbulence mechanism is highly effective, preventing particles larger than 6 micrometers from entering the lungs via the nose.
Particles between 1 and 5 micrometers in diameter that manage to bypass the nasal cavity often settle out in the small bronchioles due to:
Smaller particles settle in the bronchioles due to gravity.
What happens to particles smaller than 0.5 micrometers that remain suspended in alveolar air?
Very small particles are expelled from the lungs during exhalation.
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Which type of white blood cell is characterized by its large size and ability to leave the bloodstream to become macrophages in tissues?
Monocytes are granular leukocytes that develop into macrophages once they exit the bone marrow and enter tissues.
Monocytes originate in the:
Monocytes are formed in the bone marrow before circulating in the bloodstream.
Once in tissues, monocytes differentiate into:
Monocytes mature into macrophages when they migrate from the blood into various tissues.
Macrophages are essential for defense due to their ability to:
Macrophages are highly phagocytic cells, meaning they engulf and digest cellular debris, foreign substances, and microbes.
After engulfing particles, what do macrophages typically do with the residual products?
Macrophages are known to extrude the residual products from their cellular cytoplasm after digestion.
Macrophages secrete a protein that aids in the maturation of monocytes into macrophages and plays a role in the inflammatory response. This protein is:
Macrophages secrete Interleukin-1, which promotes monocyte maturation and contributes to inflammation and fever.
The lifespan of monocytes circulating in the blood is approximately:
Monocytes circulate in the blood for about 10-20 days before migrating into tissues.
Fixed macrophages are those that:
Macrophages can be either free-moving or fixed in tissues, where they perform their phagocytic functions.
Which of the following describes neutrophils?
Neutrophils are characterized as granular leukocytes with a multi-lobed nucleus.
What is the approximate lifespan of neutrophils in circulation?
Neutrophils typically have a short lifespan in circulation, often only a few days.
What is the primary function of neutrophils in the immune response?
Neutrophils are highly motile phagocytes that ingest bacteria and dead cells.
Neutrophils are particularly adept at:
Neutrophils are highly mobile and use pseudopodia to move and engulf targets.
Natural Killer (NK) cells are a type of lymphocyte that primarily targets:
NK cells are specialized to recognize and kill cells that have been infected by viruses or have become cancerous.
How do Natural Killer (NK) cells destroy their target cells?
NK cells secrete proteins that insert into the plasma membrane of the target cell, forming pores and leading to its destruction.
What is the primary advantage of Natural Killer (NK) cells over specific immune cells?
NK cells are part of the innate immune system and provide rapid, non-specific defense against infected or cancerous cells without requiring prior exposure to an antigen.
The complement system consists of a group of about 20 proteins found in:
Complement proteins are found in the plasma, which is the fluid component of blood.
The activation of the complement system leads to the formation of a protein complex that inserts into the cell membrane of microorganisms, causing them to burst. This complex is called:
The Membrane Attack Complex (MAC) is a key component of the complement system that creates holes in microbial membranes.
In addition to direct lysis, the complement system also amplifies the:
Activated complement proteins contribute to the inflammatory response by attracting phagocytes and promoting vasodilation.
Interferons are a group of small proteins that are secreted by cells infected with:
Interferons are produced and released by host cells in response to the presence of viruses.
What is the primary action of interferons in combating viral infections?
Interferons bind to uninfected cells, stimulating them to produce proteins that inhibit viral protein synthesis, thus preventing viral replication.
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Which type of interferon is known for enhancing the activity of Natural Killer (NK) cells?
Gamma interferon (Type II interferon) stimulates the activity of NK cells and macrophages.
Interferons are generally classified as a type of:
Interferons are a group of signaling proteins, specifically a type of cytokine, that mediate communication between cells.
Which of the following is a key mechanism by which interferons limit the spread of a virus?
Interferons warn neighboring healthy cells, making them resistant to viral infection by prompting the production of antiviral proteins.
The overall function of the complement system and interferons is to provide:
Both the complement system and interferons are components of the innate immune system, offering rapid and general defense mechanisms.
A key difference between the action of the complement system and interferons is that:
The complement system primarily causes direct destruction (lysis) of pathogens, whereas interferons act by preventing viral replication in host cells.
The inflammatory response is a localized tissue response to:
The inflammatory response is triggered by various forms of tissue injury or infection.
A systemic inflammatory response involves changes that occur throughout the body, such as:
A systemic inflammatory response can include widespread effects like an increase in white blood cell count (leukocytosis), particularly neutrophils.
During inflammation, which substance is released by basophils, causing vasodilation and increased vascular permeability?
Histamine is a key mediator released by basophils, leading to the characteristic signs of inflammation.
The increased blood flow and plasma leakage into the injured tissue during inflammation are responsible for which two cardinal signs of inflammation?
Increased blood flow causes redness and warmth, while increased vascular permeability leads to fluid leakage, causing swelling (edema).
One of the main purposes of the inflammatory response is to:
The inflammatory response brings immune cells and antimicrobial substances to the site of injury to eliminate pathogens and clear debris.
The accumulation of dead neutrophils, bacteria, and tissue debris at an infection site forms a thick, yellowish fluid called:
Pus is a common outcome of bacterial infections, consisting of dead immune cells, bacteria, and necrotic tissue.
A fever is an abnormally high body temperature that can be caused by:
Besides infections, brain abnormalities, like tumors, can also affect the thermoregulatory center and cause fever.
Substances that cause fever by acting on the hypothalamus to raise the body's temperature set-point are known as:
Pyrogens (e.g., bacterial lipopolysaccharide, toxins, or endogenous pyrogens like IL-1) reset the hypothalamic thermostat to a higher temperature.
Which medication is a common antipyretic that reduces fever by inhibiting prostaglandin synthesis in the hypothalamus?
Aspirin is a non-steroidal anti-inflammatory drug (NSAID) that acts as an antipyretic by blocking prostaglandin synthesis.
One way fever helps the body fight infection is by:
Fever makes iron less available to bacteria, which require it for growth, and also enhances interferon production, boosting antiviral defense.
The third line of defense, or adaptive immunity, is highly dependent on the cells of the:
The lymphatic system, including its cells (lymphocytes), is central to the specific (adaptive) immune response.
The effectiveness of the third line of defense relies on the ability of immune cells to:
Adaptive immunity is characterized by its specificity, where immune cells target particular antigens.
Foreign substances that elicit an immune response, such as the production of antibodies, are called:
Antigens are molecules, often foreign, that are recognized by the immune system and can trigger an immune response.
A small molecule that is not antigenic by itself but can become antigenic when bound to a larger carrier molecule is called a:
Haptens are small molecules that require conjugation to a carrier protein to become immunogenic.
The immune system primarily distinguishes between 'self' and 'non-self' based on:
The immune system identifies foreignness by recognizing specific antigenic determinants on molecules.
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Which of the following is an example of an exogenous antigen?
Exogenous antigens are those that enter the body from the outside, such as bacterial toxins.
The type of specific immunity that involves the production of antibodies by B cells is known as:
Humoral immunity relies on antibodies circulating in the body fluids (humors).
Which type of specific immunity primarily involves T lymphocytes directly attacking infected cells or regulating other immune cells?
Cell-mediated immunity involves T cells directly engaging with target cells or orchestrating immune responses.
Humoral immunity is most effective against:
Antibodies are effective at neutralizing pathogens and toxins circulating in body fluids before they can infect cells.
Cell-mediated immunity is crucial for combating:
Cell-mediated immunity, particularly cytotoxic T cells, is essential for identifying and eliminating cells that have become abnormal (e.g., infected or cancerous).
Which cells of the immune system are primarily responsible for producing antibodies?
B cells differentiate into plasma cells, which are the primary antibody-producing cells.
T lymphocytes mature in the:
T cells undergo maturation and selection in the thymus gland.
What is the primary role of Helper T cells in the adaptive immune response?
Helper T cells play a central role in orchestrating both humoral and cell-mediated immune responses by secreting cytokines that activate other immune cells.
Cytotoxic T cells primarily recognize and kill target cells that display:
Cytotoxic T cells recognize processed endogenous antigens presented on MHC class I molecules, typically found on all nucleated cells.
Memory cells are a crucial component of adaptive immunity because they:
Memory cells provide immunological memory, allowing for a more rapid and robust response upon re-exposure to the same pathogen.
Which type of lymphocyte is responsible for immunological surveillance against cancer cells?
Cytotoxic T cells recognize and eliminate tumor cells expressing abnormal antigens.
Which of the following cells presents antigens to Helper T cells?
Macrophages, dendritic cells, and B cells can function as Antigen-Presenting Cells (APCs) to activate Helper T cells by presenting antigens on MHC class II molecules.
Eosinophils are granulocytes primarily involved in defense against:
Eosinophils are associated with allergic responses and defense against helminthic (worm) infections.
Basophils play a key role in allergic reactions by releasing:
These cells degranulate and release histamine, which contributes to the symptoms of allergic reactions.
The human lymphatic system is composed of lymph vessels, lymphoid masses, lymph nodes, and:
The lymphatic system consists of vessels, lymphoid organs, nodes, and the fluid called lymph that flows within it.
In addition to the blood circulatory system, what other system is responsible for the transport of materials and returns substances from tissues to blood?
The lymphatic system works in parallel with the blood circulatory system to transport materials and maintain fluid balance.
The branches of lymph capillaries found in the villi of the small intestine, responsible for absorbing fatty acids and glycerol, are called:
Lacteals are specialized lymphatic capillaries in the intestinal villi that absorb digested fats.
Fatty acids and glycerol are absorbed into the epithelial cells of villi, where they form triglycerides, which are then coated with proteins to form:
Chylomicrons are lipoprotein particles formed in the enterocytes that transport dietary lipids to the body.
The lymphatic system begins with small vessels called lymph capillaries, which have blind endings in the:
Lymph capillaries originate as blind-ended tubules in the Extracellular fluid (interstitial fluid), collecting excess fluid from tissues.
Compared to blood capillaries, lymph capillaries are:
Lymph capillaries have highly permeable walls, allowing larger molecules and excess fluid to enter easily.
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
Get all MCQs & Detailed Explanations
When interstitial fluid enters lymph capillaries, it is then referred to as:
Once interstitial fluid enters the lymphatic capillaries, it becomes lymph.
Lymph capillaries join to form larger lymphatic vessels, which eventually converge to form two main lymph ducts: the right lymphatic duct and the:
The thoracic duct is the largest lymphatic vessel, draining lymph from most of the body.
The right lymphatic duct and the thoracic duct both open into:
These major lymphatic ducts return lymph to the bloodstream by emptying into the subclavian veins.
Which of the following mechanisms helps maintain the flow of lymph through the lymphatic vessels?
Lymph flow is largely facilitated by skeletal muscle contractions compressing the vessels and one-way valves preventing backflow.
One of the key functions of the lymphatic system is to return excess fluid and proteins from the interstitial spaces to the:
The lymphatic system collects excess interstitial fluid and plasma proteins that have leaked from capillaries and returns them to the circulation, maintaining blood volume and pressure.
The lymphatic system plays a crucial role in the body's defense by:
Lymph nodes filter lymph, and lymphoid organs produce lymphocytes, which are key immune cells.
Small, bean-shaped structures found along lymphatic vessels that filter lymph and contain lymphocytes and macrophages are called:
Lymph nodes are strategically located to filter lymph and initiate immune responses.
Lymph nodes are typically present in clusters in regions such as the neck, axilla (armpit), and:
Common locations for lymph node clusters include the neck, axilla, and groin.
What happens to lymph as it passes through a lymph node?
Lymph nodes act as filters, removing pathogens and debris from lymph and exposing them to immune cells.
Which of the following is considered one of the larger lymphoid masses in the body?
The spleen is a major lymphoid organ, alongside the thymus, tonsils, and adenoids.
The spleen is primarily responsible for:
The spleen functions to filter blood, remove old red blood cells, and store blood components.
Which lymphoid mass is crucial for the maturation of T lymphocytes?
The thymus is the primary lymphoid organ where T cells mature and differentiate.
Tonsils and adenoids are examples of lymphoid masses that primarily produce:
Tonsils and adenoids, like other lymphoid tissues, contain and produce lymphocytes, contributing to local immune defense.
The collection of lymph nodes, lymph vessels, and lymphoid masses constitutes the system primarily involved in:
The lymphatic system's main roles are to maintain fluid homeostasis and provide immune defense.
Rheumatoid arthritis is an autoimmune disorder characterized by the immune system attacking:
Rheumatoid arthritis is a chronic inflammatory disorder that primarily affects the lining of the joints.
In rheumatoid arthritis, the body produces autoantibodies that target:
A hallmark of rheumatoid arthritis is the presence of rheumatoid factor, which are autoantibodies against the Fc portion of IgG.
Which immune cells are found in the synovial fluid of affected joints in rheumatoid arthritis and contribute to the inflammation?
The synovial fluid in rheumatoid arthritis is infiltrated with various immune cells, including T cells, plasma cells (producing autoantibodies), and macrophages.
The inflammation and joint damage in rheumatoid arthritis are largely mediated by the release of:
Pro-inflammatory cytokines, such as TNF-alpha and IL-6, play a critical role in the pathogenesis of rheumatoid arthritis.
Rheumatoid arthritis is classified as an autoimmune disease because:
Autoimmune diseases occur when the immune system loses its ability to distinguish between self and non-self, leading to an attack on the body's own components.
Other Biology MCQs
Want to look through some MCQs for your Upcoming tests, take a look at the following Grammar tests: