BIO 242 EXAM 3 TEST BANK 2026 FULLY
SOLVED QUESTIONS AND COMPLETE
SOLUTIONS
◎ how do physical barriers help with immunity? ANSWER: - inhibits pathogen growth and
blocks the pathogen from entry into the body
skin: tightly packed epithelial cells, keratin, low pH
mucous membranes: trap microbes, cilia move them out
mechanical removal: tears, saliva, earwax, urine; pushes pathogen out of the body
◎ how do chemical barriers help with immunity? ANSWER: - lysozyme (tears, saliva, sweat):
breaks down peptidoglycan in bacterial walls
sebum: oily secretions that inhibit microbes
acidic environments: stomach acid, vaginal pH; most pathogens not able to survive
◎ how does the body's microbiota help with immunity? ANSWER: - normal flora outcompete
pathogens for survival
◎ immune system second line of defense ANSWER: - nonspecific, internal
-cellular defenses: macrophages, natural killer cells
-inflammation, fever, complement system, interferons
◎ cellular defenses of the 2nd line of defense (phagocytes & NK cells) ANSWER: - phagocytes:
neutrophils- 1st responder; engulf bacteria
macrophages- long term clean up; phagocytize foreign pathogens & dead cells
dendritic cells- capture antigens & present to T cells; bridge to adaptive immunity
natural killer cells: lymphocyte; kills virus infected cells; use perforin & granulocytes to induce
apoptosis
◎ inflammation ANSWER: - redness, heat, swelling, pain, loss of function
-Increases blood flow, recruits immune cells to the infected area
◎ fever ANSWER: - systemic increase in body temperature, inhibits microbes and boosts
metabolism
, ◎ complement system ANSWER: - a group of plasma proteins that work together in a cascade
to fight infections
-classical, alternative, and lectin pathways; leads to end product (membrane attack complex or
MAC)
◎ classical pathway ANSWER: - triggered by antibodies binding to microbial invaders
◎ alternative pathway ANSWER: - begins when complement proteins bind to normal cell wall
and surface components of microorganisms
◎ lectin pathway ANSWER: - mannose-binding lectin binds to sugars on microbes
◎ Membrane Attack Complex (MAC) ANSWER: - end product of each pathway
forms pores in microbial membranes; results in lysing/bursting of bacteria
◎ interferons ANSWER: - -Produced by virus-infected cells.
-Warn neighboring cells to produce antiviral proteins.
-the infected cell is sacrificed
◎ immune system 3rd line of defense ANSWER: - adaptive and specific
- T cells, B cells, antibodies, antigen recognition
◎ what are the types of T cells ANSWER: - Cytotoxic T cells
Helper T cells
Memory T cells
◎ Cytotoxic T cells (CD8) ANSWER: - release perforin + granzyme → directly kill infected cells by
inducing apoptosis
recognize MHC Class 1 antigens
◎ Helper T cells (CD4) ANSWER: - secrete cytokines, which activates B cells & cytotoxic T cells.
recognize MHC Class 2 antigens
◎ Memory T cells ANSWER: - long lasting defense; Provides a faster and stronger response
upon re-exposure to a pathogen.
SOLVED QUESTIONS AND COMPLETE
SOLUTIONS
◎ how do physical barriers help with immunity? ANSWER: - inhibits pathogen growth and
blocks the pathogen from entry into the body
skin: tightly packed epithelial cells, keratin, low pH
mucous membranes: trap microbes, cilia move them out
mechanical removal: tears, saliva, earwax, urine; pushes pathogen out of the body
◎ how do chemical barriers help with immunity? ANSWER: - lysozyme (tears, saliva, sweat):
breaks down peptidoglycan in bacterial walls
sebum: oily secretions that inhibit microbes
acidic environments: stomach acid, vaginal pH; most pathogens not able to survive
◎ how does the body's microbiota help with immunity? ANSWER: - normal flora outcompete
pathogens for survival
◎ immune system second line of defense ANSWER: - nonspecific, internal
-cellular defenses: macrophages, natural killer cells
-inflammation, fever, complement system, interferons
◎ cellular defenses of the 2nd line of defense (phagocytes & NK cells) ANSWER: - phagocytes:
neutrophils- 1st responder; engulf bacteria
macrophages- long term clean up; phagocytize foreign pathogens & dead cells
dendritic cells- capture antigens & present to T cells; bridge to adaptive immunity
natural killer cells: lymphocyte; kills virus infected cells; use perforin & granulocytes to induce
apoptosis
◎ inflammation ANSWER: - redness, heat, swelling, pain, loss of function
-Increases blood flow, recruits immune cells to the infected area
◎ fever ANSWER: - systemic increase in body temperature, inhibits microbes and boosts
metabolism
, ◎ complement system ANSWER: - a group of plasma proteins that work together in a cascade
to fight infections
-classical, alternative, and lectin pathways; leads to end product (membrane attack complex or
MAC)
◎ classical pathway ANSWER: - triggered by antibodies binding to microbial invaders
◎ alternative pathway ANSWER: - begins when complement proteins bind to normal cell wall
and surface components of microorganisms
◎ lectin pathway ANSWER: - mannose-binding lectin binds to sugars on microbes
◎ Membrane Attack Complex (MAC) ANSWER: - end product of each pathway
forms pores in microbial membranes; results in lysing/bursting of bacteria
◎ interferons ANSWER: - -Produced by virus-infected cells.
-Warn neighboring cells to produce antiviral proteins.
-the infected cell is sacrificed
◎ immune system 3rd line of defense ANSWER: - adaptive and specific
- T cells, B cells, antibodies, antigen recognition
◎ what are the types of T cells ANSWER: - Cytotoxic T cells
Helper T cells
Memory T cells
◎ Cytotoxic T cells (CD8) ANSWER: - release perforin + granzyme → directly kill infected cells by
inducing apoptosis
recognize MHC Class 1 antigens
◎ Helper T cells (CD4) ANSWER: - secrete cytokines, which activates B cells & cytotoxic T cells.
recognize MHC Class 2 antigens
◎ Memory T cells ANSWER: - long lasting defense; Provides a faster and stronger response
upon re-exposure to a pathogen.
