Question 1
Microbiology Quiz (Laboratory). What enzyme converts H2O2 into H2O without producing O2?
- catalase
- peroxidase
- oxidase
- coagulase
Question 2
A bacterium might be able to ferment sucrose, but be unable to ferment lactose because:
- it lacks the glucose needed for fermentation
- sucrose is a monosaccharide while lactose is a disaccharide
- it lacks an enzyme that can cleave lactose into monosaccharides
- lactose can only be fermented by an aerobe
Question 3
The phenol red in a fermentation tube is used because:
- it can detect the production of gas during fermentation
- it provides a source of nutrients for the bacteria
- it helps to keep the media anaerobic
- it can detect the production of organic acids during fermentation
Question 4
An organism that requires oxygen to grow and is very capable of detoxifying toxic oxygen derivatives is termed a(n):
- obligate aerobe
- obligate anaerobe
- facultative anaerobe
- microaerophile
- aerotolerant anaerobe
Question 6
Melted agar deeps must be boiled after being autoclaved but before being inoculated because:
- the heat will kill any contaminating bacteria
- it helps to mix the nutrients in the media
- boiling drives off the oxygen gas dissolved in the media
- it ensures the media will remain liquid during inoculation
Question 7
Which of the following possesses enzymes that detoxify oxygen compounds and can only grow in the presence of O2?
- facultative anaerobe
- obligate anaerobe
- aerotolerant anaerobe
- obligate aerobe
Question 8
The enzyme coagulase can cause which of the following to occur?
- clotting of blood
- hydrolysis of urea
- production of oxygen gas
- formation of indole
Question 9
To test for motility, one uses a(n) _______ to introduce bacteria into soft agar.
- inoculating loop
- inoculating needle
- pipette
- cotton swab
Question 10
A positive test for oxidase _______.
- forms clots
- produces bubbles trapped in a Durham tube
- turns the red media yellow
- produces a blue color
Question 11
What is the function of cytochrome c oxidase?
- it detoxifies hydrogen peroxide
- it hydrolyzes a covalent bond within lactose
- it is a component of the respiratory electron transport chain
- it propels the cell in a process termed chemiosmosis
- it reacts with plasma proteins to produce clots
Question 12
Which of the following cannot be detected by SIM media?
- reduction of cysteine
- formation of indole
- bacterial motility
- presence of flagella
- detoxification of peroxide anion
Question 13
What type of molecule is cysteine?
- amino acid
- sugar
- nucleic acid
- fatty acid
Question 14
What type of molecule is tryptophan?
- sugar
- amino acid
- nucleic acid
- fatty acid
Question 15
What is the purpose of the bromthymol blue in citrate media?
- carbon source
- pH indicator
- nitrogen source
- solidifying agent. Microbiology Quiz (Laboratory).
Question 16
What is generally NOT required by bacteria growing on citrate media? Microbiology Quiz (Laboratory).
- nitrogen
- source of carbon
- source of energy
- growth factors
- nutrients
- water
Question 17
Urease-positive bacteria turn urea agar:
- yellow
- blue
- pink
- black
Question 18
How does the enzyme urease benefit the bacterium Helicobacter pylori?
- it degrades the mucus coating the epithelial cells of the stomach
- it generates a proton gradient that can fuel the movement of its flagella
- it inhibits competing microbes by acidifying the environment
- it neutralizes the acidic environment of the stomach
- it produces ATP and reduced coenzymes by hydrolyzing urea
- it breaks down urea and other nitrogen-containing molecules so they can be absorbed in the small intestine
Question 19
Which of the following is a function of bile salts in humans?
- aid in digestion of fats
- assist immune system in recognizing pathogens
- enzymatically convert starch into simple sugars
- promote clotting of blood
- stimulate phagocytic action of leukocytes
- NONE of these are functions of bile salts
Question 20
Which of the following is both esculin positive Gram-positive?
- Enterococcus faecalis
- Escherichia coli
- Klebsiella pneumoniae
- Staphylococcus aureus
- ALL these are both Gram-positive and esculin positive
- NONE of these are both Gram-positive and esculin positive
Question 21
________________ are virulence factors that cause red blood cells to burst.
- Catalase and peroxidase
- Flagella
- Hemolysins
- Lactase and sucrase
- Oxidase enzymes
- Urease enzymes
Question 22
A colony on blood agar surrounded by an opaque greenish “halo” is displaying ________________.
- a lack of hemolysis
- alpha hemolysis
- beta hemolysis
- citrate catabolism
- gamma hemolysis
- urea hydrolysis
Question 23
What bacterial species is the cause of “strep throat?”
- Enterococcus faecalis
- Streptococcus agalactiae
- Streptococcus mutans
- Streptococcus pneumoniae
- Streptococcus pyogenes
- Streptococcus salivarius
