Free Specific Defense Mechanism MCQs with Answers

• A. contains weakened pathogens
• B. contains ready made antibodies and gives only temporary protection
• C. produces lifelong immunity
• D. stimulates the formation of memory cells

Explanation: Antiserum lends antibodies for immediate, short lived defence, while a vaccine teaches the body to make its own, lasting protection.

• A. artificially active immunity
• B. artificially passive immunity
• C. naturally passive immunity
• D. innate immunity

Explanation: The body actively responds and makes memory, but the exposure is deliberate and medical rather than natural infection.

• A. carrying oxygen to the wound
• B. digesting food particles
• C. producing antigens
• D. forming pores in the bacterial membrane that cause lysis

Explanation: Complement proteins assemble into a membrane attack complex that punches holes in pathogen membranes, and also coat microbes for…

• A. creates antibodies from scratch
• B. converts T cells into B cells
• C. selects and stimulates the lymphocyte clone bearing the matching receptor
• D. suppresses every lymphocyte equally

Explanation: The body already holds millions of lymphocyte clones, each with one receptor; the antigen simply picks the matching one and drives its…

• A. first line of defence
• B. second line of defence
• C. third line of defence
• D. adaptive immune system

Explanation: These physical and chemical barriers stop most pathogens from entering at all, before any cellular response is needed.

• A. antibody production by plasma cells
• B. phagocytosis, inflammation and fever
• C. the action of memory cells
• D. vaccination

Explanation: These responses act rapidly and without targeting a specific antigen, attacking anything foreign.

• A. cross immunity
• B. passive immunity
• C. herd immunity
• D. autoimmunity

Explanation: Vaccinated people act as dead ends for transmission, shielding those too young or too ill to be vaccinated.

• A. memory cells are destroyed to reset the system
• B. the antigens multiply and cause the full disease
• C. the vaccine replaces the plasma proteins
• D. antigens stimulate lymphocytes, producing plasma cells and memory cells

Explanation: The weakened or dead antigens cannot cause disease but are presented to lymphocytes, which respond exactly as in infection, leaving memory…

• A. They act as receptors of pathogens
• B. They are long term energy reserves
• C. They act as antibodies
• D. They act as mechanical barrier for pathogens

Explanation: Antibodies are immunoglobulins, that is proteins, and they are the specific weapon of the humoral response, binding one antigen each.

• A. Humoral immunity involves B-Lymphocytes and cell mediated immunity involves T-Lymphocytes
• B. Humoral immunity destroys viruses and cell mediated immunity destroys bacteria
• C. Humoral immunity is specific and cell mediated immunity is nonspecific
• D. Humoral immunity uses antibodies and cell mediated immunity does not involve immune cells

Explanation: B cells give rise to plasma cells whose antibodies circulate in the body fluids, which is the humoral arm, while T cells act directly on…

• A. etiology
• B. serology
• C. ecology
• D. histology

Explanation: Serology is the study of blood serum, especially the antibodies and antigens found in it and their reactions.

• A. White Blood cells
• B. Red Blood Cells
• C. Platelets
• D. Plasma

Explanation: White blood cells defend a wound by recognizing, engulfing, or destroying invading bacteria and by coordinating immune responses.

• A. Smallpox
• B. Jaundice
• C. Diabetes
• D. None of these

Explanation: A person who recovers from smallpox develops specific immune memory against the smallpox virus, although vaccination is the safer way to…

• A. B-Lymphocytes
• B. T-lymphocytes
• C. Both B and T lymphocytes
• D. RBCs

Explanation: Organ rejection is primarily a cell-mediated immune response in which T lymphocytes recognize foreign major histocompatibility complex…

• A. RBCs
• B. Platelets
• C. White Blood Cells
• D. Hemoglobin

Explanation: Pus contains dead and living white blood cells, destroyed microbes and tissue debris accumulated during an inflammatory response.

• A. Leprosy
• B. Tuberculosis
• C. Cancer
• D. None of the above

Explanation: BCG is a vaccine used mainly to provide protection against tuberculosis, particularly severe forms of childhood TB.

• A. Acclimatization
• B. Agglutination
• C. Paralysis
• D. Phagocytosis

Explanation: Phagocytosis is the process in which cells such as neutrophils and macrophages engulf and digest bacteria or other particles.

• A. Artificially induced active immunity
• B. Naturally induced active immunity
• C. Artificially induced passive immunity
• D. Naturally induced passive immunity

Explanation: A vaccine is deliberately introduced into the body and stimulates the person's own lymphocytes to form antibodies and memory cells, so it…

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: A typical antibody has four polypeptide chains: two identical heavy chains and two identical light chains joined by disulfide bonds.

• A. Memory cells are produced in the plasma
• B. Lymphocytes are produced in the bone marrow
• C. T-lymphocytes are required to stimulate the immune system
• D. Antibodies are required to increase the production of B-lymphocytes

Explanation: Memory cells are specialized Lymphocytes that enable a faster response on re-exposure to same pathogen.