Bio 400 Exam Questions With All
Correct Answers <Verified Answers>
2025 Marking Scheme New Update
define the term antigen - CORRECT ANSWER-any substance recognized by the
immune system
identify the barriers that help prevent microbial invasion of the host - CORRECT
ANSWER-physical and chemical
explain how the physical and mechanical barriers function to prevent microbial
invasion of the host - CORRECT ANSWER-physical: skin, mucus membrane
(trap and destroy pathogens and have antimicrobial peptides), respiratory system,
stomach (low ph), intestines (have pancreatic enzymes and normal microbiota), GI
tract (flush system)
chemical: found in secretions
relate host anatomy and secretions to the success of innate resistance strategies -
CORRECT ANSWER-tears, mucus, breast milk
, differentiate between lysozyme, lactoferrin, and lactoperoxidase - CORRECT
ANSWER-- lysozyme: enzyme that cuts glycosidic bond between NAG-NAM
within petidoglycan (cell wall)
- lactoferrin: sequesters iron (iron grows bacteria)
- lactoperoxidase: catalyzes production of superoxide radicals toxic to microbes
define defensins and their function - CORRECT ANSWER-antimicrobial peptides
that destroy invaders of the cell membrane, are small and cationic
describe in general terms the activation of the host alternative complement system
and its three outcomes - CORRECT ANSWER-the cascade is activated in the
presence of a pathogen; 1) increase inflammation, 2) lyse pathogen, 3)increase
phagocytosis
identify the complement proteins involved in the process - CORRECT ANSWER-
- once C3 is cleaved LPS binds to C3b which binds to other components of the
cascade and forms C3 convertase
- C3 convertase cleaves C3 which increase production of C3b and C3a
- C3a is chemoattractant that floats away and attracts immune cells and C3b
cleaves C5
COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED
Correct Answers <Verified Answers>
2025 Marking Scheme New Update
define the term antigen - CORRECT ANSWER-any substance recognized by the
immune system
identify the barriers that help prevent microbial invasion of the host - CORRECT
ANSWER-physical and chemical
explain how the physical and mechanical barriers function to prevent microbial
invasion of the host - CORRECT ANSWER-physical: skin, mucus membrane
(trap and destroy pathogens and have antimicrobial peptides), respiratory system,
stomach (low ph), intestines (have pancreatic enzymes and normal microbiota), GI
tract (flush system)
chemical: found in secretions
relate host anatomy and secretions to the success of innate resistance strategies -
CORRECT ANSWER-tears, mucus, breast milk
, differentiate between lysozyme, lactoferrin, and lactoperoxidase - CORRECT
ANSWER-- lysozyme: enzyme that cuts glycosidic bond between NAG-NAM
within petidoglycan (cell wall)
- lactoferrin: sequesters iron (iron grows bacteria)
- lactoperoxidase: catalyzes production of superoxide radicals toxic to microbes
define defensins and their function - CORRECT ANSWER-antimicrobial peptides
that destroy invaders of the cell membrane, are small and cationic
describe in general terms the activation of the host alternative complement system
and its three outcomes - CORRECT ANSWER-the cascade is activated in the
presence of a pathogen; 1) increase inflammation, 2) lyse pathogen, 3)increase
phagocytosis
identify the complement proteins involved in the process - CORRECT ANSWER-
- once C3 is cleaved LPS binds to C3b which binds to other components of the
cascade and forms C3 convertase
- C3 convertase cleaves C3 which increase production of C3b and C3a
- C3a is chemoattractant that floats away and attracts immune cells and C3b
cleaves C5
COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED
