1
BIOS242 EXAM 3 REVIEW Questions
and Answers (100% Correct
Answers) Already Graded A+
First Line Defense Ans: •Barriers that block invasion at the
portal of entry
© 2026 Assignment
•Does not involve recognition of foreign substances
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•General in action
Second Line Defense Ans: •Nonspecific
•Internalized system of protective cells and fluids
•Inflammation and phagocytosis
•Acts rapidly at the local and systemic levels
Third Line of Defense Ans: •Acquired on an individual basis
as each foreign substance is encountered by lymphocytes
•Produces unique protective substances and cells that can
come into play if the microbe is encountered again
•Provides long-term immunity
Neutrophils Ans: •Phagocytic
•Found in blood
, 2
•First to respond
•Increase during bacterial infections
Eosinophils Ans: •Active in protozoal, helminth reactions
•Usually found in low numbers
•Elevated in allergic reactions
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Basophils Ans: •Function in inflammatory events
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•Usually found in low numbers
Expert
Mast Cells Ans: •Found in the tissues
•Similar to basophils
•Contain histamine
Monocytes Ans: Blood phagocytes that rapidly leave the
circulation; mature into macrophages and dendritic cells.
Macrophages Ans: Large phagocytic cells; high capacity for
killing microbes and cleaning up dead cells; antigen-presenting
cells.
Dendritic cells Ans: Reside in tissues and MPS; process
foreign matter and present it to lymphocytes; antigen-
presenting cells.
T cell Ans: Cell-mediated immunity; assist B cells
, 3
B cell Ans: Differentiate into plasma cells and release
antibody; antigen-presenting cells
Natural killer (NK) cells Ans: Related to T cells but do not act
specifically
Chemotaxis Ans: Phagocytes must move to the site of injury.
They follow the trails of chemicals released by damaged
tissues.
© 2026 Assignment
Pathogen-associated molecular patterns (P A M P's) Ans:
Markers that many microbes have in common
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Pattern recognition receptors (PRRs) Ans: Used by host cells
to recognize PAMP's
Complement System Ans: It is a vital part of the immune
defense, working in concert with other components of the
immune system to protect the body from infections.
Classical Pathway Ans: This pathway is initiated when
antibodies bind to pathogens, leading to the activation of
complement proteins.
Lectin Pathway Ans: This pathway is activated by the binding
of lectin (a type of protein) to specific carbohydrates on the
surface of pathogens.
Alternative Pathway Ans: This pathway can be activated
directly by the presence of pathogens without the need for
antibodies.
cascade activation Ans: Once any of these pathways are
initiated, the complement proteins undergo a
BIOS242 EXAM 3 REVIEW Questions
and Answers (100% Correct
Answers) Already Graded A+
First Line Defense Ans: •Barriers that block invasion at the
portal of entry
© 2026 Assignment
•Does not involve recognition of foreign substances
Guru01 - Stuvia
Expert
•General in action
Second Line Defense Ans: •Nonspecific
•Internalized system of protective cells and fluids
•Inflammation and phagocytosis
•Acts rapidly at the local and systemic levels
Third Line of Defense Ans: •Acquired on an individual basis
as each foreign substance is encountered by lymphocytes
•Produces unique protective substances and cells that can
come into play if the microbe is encountered again
•Provides long-term immunity
Neutrophils Ans: •Phagocytic
•Found in blood
, 2
•First to respond
•Increase during bacterial infections
Eosinophils Ans: •Active in protozoal, helminth reactions
•Usually found in low numbers
•Elevated in allergic reactions
© 2026 Assignment
Basophils Ans: •Function in inflammatory events
Guru01 - Stuvia
•Usually found in low numbers
Expert
Mast Cells Ans: •Found in the tissues
•Similar to basophils
•Contain histamine
Monocytes Ans: Blood phagocytes that rapidly leave the
circulation; mature into macrophages and dendritic cells.
Macrophages Ans: Large phagocytic cells; high capacity for
killing microbes and cleaning up dead cells; antigen-presenting
cells.
Dendritic cells Ans: Reside in tissues and MPS; process
foreign matter and present it to lymphocytes; antigen-
presenting cells.
T cell Ans: Cell-mediated immunity; assist B cells
, 3
B cell Ans: Differentiate into plasma cells and release
antibody; antigen-presenting cells
Natural killer (NK) cells Ans: Related to T cells but do not act
specifically
Chemotaxis Ans: Phagocytes must move to the site of injury.
They follow the trails of chemicals released by damaged
tissues.
© 2026 Assignment
Pathogen-associated molecular patterns (P A M P's) Ans:
Markers that many microbes have in common
Guru01 - Stuvia
Expert
Pattern recognition receptors (PRRs) Ans: Used by host cells
to recognize PAMP's
Complement System Ans: It is a vital part of the immune
defense, working in concert with other components of the
immune system to protect the body from infections.
Classical Pathway Ans: This pathway is initiated when
antibodies bind to pathogens, leading to the activation of
complement proteins.
Lectin Pathway Ans: This pathway is activated by the binding
of lectin (a type of protein) to specific carbohydrates on the
surface of pathogens.
Alternative Pathway Ans: This pathway can be activated
directly by the presence of pathogens without the need for
antibodies.
cascade activation Ans: Once any of these pathways are
initiated, the complement proteins undergo a
