BIOD 171 Module 5 Exam Questions and Correct Answers Latest Update 2025
5 steps to infection - Answers 1. Entry - pathogens use portals of entry to access host tissues
2. Attachment - pathogen binds to tissues using adhesion factors
3. Invasion - pathogen invades deeper into host's tissues and secure nutrients for growth
4. Evasion - pathogen evades immune system defenses by hiding or avoiding phagocytosis or
suppressing immunity
5. Exit and transmission - portal of exit to leave host and transmit to new host (direct or indirect)
Streptococcus - Answers - Gram-positive
- round, chain-like structures
- catalase negative
- Using BAP is the quickest way to identify (hemolytic activity) because there are many subtypes
Hemolytic properties on BAP - Answers alpha-hemolysis: partial decomposition of hemoglobin; greenish-
brown color on plate (Streptococcus pneumonia)
beta-hemolysis: complete decomposition; zone of clearing (Streptococcus pyogenes and some staph
aureus)
gamma-hemolysis: no hemolytic activity; white/tan colonies on red plate (Enterococcus faecalis)
Lancefield grouping - Answers Classifies beta-hemolytic streptococcus
Catalase-negative, coagulase-negative
Groups based on carbohydrate composition of bacterial antigens in cell wall
Group A: Streptococcus pyogenes - causative agent behind 90% of strep infections
, Streptococcal Pharyngitis - Answers a group A disease characterized by fever, enlargement of lymph
nodes in the neck and a reddening within the lining of the throat surface tissue causing soreness and
discomfort
treatment: penicillin
Rheumatic Fever - Answers Streptococcus pyogenes (untreated)
beta-hemolysis
Joint inflammation, involuntary jerking movements, nodules beneath skin, can damage heart valves
treatment: penicillin
Streptococcal Septicemia - Answers Group B Streptococcus infection of the blood
fever, increased heart rate, arises from infections in lungs, abdomen, urinary tract
treatment: antibiotics, IV fluids, oxygen
can be caused by E. coli, pseudomonas, klebsiella, etc
Staphylococcus - Answers Gram-positive
Round shape, forms grape-like clusters with other bacteria
facultative anaerobe
can be found in 30% of human population asymptomatic
5 steps to infection - Answers 1. Entry - pathogens use portals of entry to access host tissues
2. Attachment - pathogen binds to tissues using adhesion factors
3. Invasion - pathogen invades deeper into host's tissues and secure nutrients for growth
4. Evasion - pathogen evades immune system defenses by hiding or avoiding phagocytosis or
suppressing immunity
5. Exit and transmission - portal of exit to leave host and transmit to new host (direct or indirect)
Streptococcus - Answers - Gram-positive
- round, chain-like structures
- catalase negative
- Using BAP is the quickest way to identify (hemolytic activity) because there are many subtypes
Hemolytic properties on BAP - Answers alpha-hemolysis: partial decomposition of hemoglobin; greenish-
brown color on plate (Streptococcus pneumonia)
beta-hemolysis: complete decomposition; zone of clearing (Streptococcus pyogenes and some staph
aureus)
gamma-hemolysis: no hemolytic activity; white/tan colonies on red plate (Enterococcus faecalis)
Lancefield grouping - Answers Classifies beta-hemolytic streptococcus
Catalase-negative, coagulase-negative
Groups based on carbohydrate composition of bacterial antigens in cell wall
Group A: Streptococcus pyogenes - causative agent behind 90% of strep infections
, Streptococcal Pharyngitis - Answers a group A disease characterized by fever, enlargement of lymph
nodes in the neck and a reddening within the lining of the throat surface tissue causing soreness and
discomfort
treatment: penicillin
Rheumatic Fever - Answers Streptococcus pyogenes (untreated)
beta-hemolysis
Joint inflammation, involuntary jerking movements, nodules beneath skin, can damage heart valves
treatment: penicillin
Streptococcal Septicemia - Answers Group B Streptococcus infection of the blood
fever, increased heart rate, arises from infections in lungs, abdomen, urinary tract
treatment: antibiotics, IV fluids, oxygen
can be caused by E. coli, pseudomonas, klebsiella, etc
Staphylococcus - Answers Gram-positive
Round shape, forms grape-like clusters with other bacteria
facultative anaerobe
can be found in 30% of human population asymptomatic
