1
Microbiology Lab 8 Questions with Correct
Answers | Updated (100% Correct Answers)
GI bacteria Answer: • the stomach and small intestine contain
relatively few bacteria
• the large intestine bacterial populations are significant
why does the stomach and small intestine contain relatively few
bacteria? Answer: • HCl produced by the stomach is unbearable for
most bacteria
• rapid movement of food through the small intestine prevents
attachement (peristalsis)
large intestine bacteria Answer: • primarily in the colon
• up to 10^11 bacteria per gram of feces
• most are commensals
commensal bacteria in feces Answer: • mutualistic relationship with
host
• make us vitamin K and folic acid
gastrointestinal diseases Answer: • most GI diseases result from the
ingestion of contaminated food or water
© 2025 All rights reserved
, 2
• prevented by good sanitation/hygiene practices
problem with GI diseases Answer: • separating and identifying the
normal inhabitants from the pathogens
• large intestine consists primarily of anaerobes
• most fecal contamination is associated with gram negative
facultative anaerobes
upper GI Answer: • stomach and duodenum
• biopsy
lower GI Answer: • small and large intestine
• stool
• rectal swab
• sometimes blood cultures
stool Answer: • requires selective and differential media
• Salmonella and Shigella spp. may require enrichment media
typhoid fever Answer: results from Salmonella infection
MAC agar Answer: • MacConkey Agar
© 2025 All rights reserved
Microbiology Lab 8 Questions with Correct
Answers | Updated (100% Correct Answers)
GI bacteria Answer: • the stomach and small intestine contain
relatively few bacteria
• the large intestine bacterial populations are significant
why does the stomach and small intestine contain relatively few
bacteria? Answer: • HCl produced by the stomach is unbearable for
most bacteria
• rapid movement of food through the small intestine prevents
attachement (peristalsis)
large intestine bacteria Answer: • primarily in the colon
• up to 10^11 bacteria per gram of feces
• most are commensals
commensal bacteria in feces Answer: • mutualistic relationship with
host
• make us vitamin K and folic acid
gastrointestinal diseases Answer: • most GI diseases result from the
ingestion of contaminated food or water
© 2025 All rights reserved
, 2
• prevented by good sanitation/hygiene practices
problem with GI diseases Answer: • separating and identifying the
normal inhabitants from the pathogens
• large intestine consists primarily of anaerobes
• most fecal contamination is associated with gram negative
facultative anaerobes
upper GI Answer: • stomach and duodenum
• biopsy
lower GI Answer: • small and large intestine
• stool
• rectal swab
• sometimes blood cultures
stool Answer: • requires selective and differential media
• Salmonella and Shigella spp. may require enrichment media
typhoid fever Answer: results from Salmonella infection
MAC agar Answer: • MacConkey Agar
© 2025 All rights reserved
