Microbiology Quiz (Laboratory)

Question 1

Microbiology Quiz (Laboratory). What enzyme converts H2​O2​ into H2​O without producing O2​?

• catalase
• peroxidase
• oxidase
• coagulase

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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

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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

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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

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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

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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

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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

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Question 9

To test for motility, one uses a(n) _______ to introduce bacteria into soft agar.

• inoculating loop
• inoculating needle
• pipette
• cotton swab

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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

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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

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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

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Question 13

What type of molecule is cysteine?

• amino acid
• sugar
• nucleic acid
• fatty acid

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Question 14

What type of molecule is tryptophan?

• sugar
• amino acid
• nucleic acid
• fatty acid

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Question 15

What is the purpose of the bromthymol blue in citrate media?

• carbon source
• pH indicator
• nitrogen source
• solidifying agent. Microbiology Quiz (Laboratory).

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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

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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