Microbiology Chapter 6 test bank
Micrococci are facultative halophiles. In Figure 6.1, which line best depicts the growth of M.
luteus in a nutrient medium containing 7.5% NaCl?
A) a
B) b
C) c - correct answer B
The addition of which of the following to a culture medium will neutralize acids?
A) Buffers
B) Sugars
C) pH
D) Heat
E) Carbon - correct answer Buffers
Salts and sugars work to preserve foods by creating a
A) Depletion of nutrients.
B) Hypotonic environment.
C) Lower osmotic pressure.
D) Hypertonic environment.
E) Lower pH. - correct answer Hypertonic environment
The term facultative anaerobe refers to an organism that
A) Doesnʹt use oxygen but tolerates it.
B) Is killed by oxygen.
C) Uses oxygen or grows without oxygen.
D) Requires less oxygen than is present in air.
E) Prefers to grow without oxygen. - correct answer Uses oxygen or grows without oxygen
,Microbiology Chapter 6 test bank
Which of the following is not a disadvantage of the standard plate count?
A) Cells may form aggregates.
B) Requires incubation time.
C) Determines viable cells.
D) Chemical and physical requirements are determined by media and incubation.
E) None of the above. - correct answer Determines viable cells
Which of the following is not a disadvantage of the direct microscopic count?
A) Some organisms are motile.
B) Enumerates dead cells.
C) No incubation time.
D) Sample volume is unknown.
E) Large number of cells is required. - correct answer Sample volume is unknown
Which of the following is not used to determine metabolic activity?
A) Acid production from fermentation.
B) CO 2 produced from the Krebs cycle.
C) NO2- produced from the electron transport chain.
D) Decreased dissolved oxygen.
E) Turbidity. - correct answer Turbidity
Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate
count. How many cells were in the original sample?
A) 4
B) 9
C) 18
D) 36
E) 72 - correct answer 72
, Microbiology Chapter 6 test bank
Most bacteria grow best at pH
A) 1.
B) 5.
C) 7.
D) 9.
E) 14. - correct answer 7
Figure 6.3 shows three containers of water connected by tubes. A selectively permeable
membrane divides each tube. Solutes are added to each container to give final concentrations
of 5% NaCl in a; 10% NaCl in b; and 5% sucrose in c. When the experiment is first set up, the
initial movement of water will be
A) a to b; b to c; c to a.
B) a to b; c to b; c to a.
C) a to c; b to c; c to a.
D) a to c; c to b; c to a.
E) b to a; b to c; c to a. - correct answer a to b; c to b; c to a
A culture medium on which only gram-positive organisms grow and a yellow halo surrounds
Staphylococcus aureus colonies is called a(n)
A) Selective medium.
B) Differential medium.
C) Enrichment culture.
D) A and B.
E) B and C. - correct answer A and B
A culture medium consisting of agar, human blood, and beef heart is a
A) Chemically defined medium.
Micrococci are facultative halophiles. In Figure 6.1, which line best depicts the growth of M.
luteus in a nutrient medium containing 7.5% NaCl?
A) a
B) b
C) c - correct answer B
The addition of which of the following to a culture medium will neutralize acids?
A) Buffers
B) Sugars
C) pH
D) Heat
E) Carbon - correct answer Buffers
Salts and sugars work to preserve foods by creating a
A) Depletion of nutrients.
B) Hypotonic environment.
C) Lower osmotic pressure.
D) Hypertonic environment.
E) Lower pH. - correct answer Hypertonic environment
The term facultative anaerobe refers to an organism that
A) Doesnʹt use oxygen but tolerates it.
B) Is killed by oxygen.
C) Uses oxygen or grows without oxygen.
D) Requires less oxygen than is present in air.
E) Prefers to grow without oxygen. - correct answer Uses oxygen or grows without oxygen
,Microbiology Chapter 6 test bank
Which of the following is not a disadvantage of the standard plate count?
A) Cells may form aggregates.
B) Requires incubation time.
C) Determines viable cells.
D) Chemical and physical requirements are determined by media and incubation.
E) None of the above. - correct answer Determines viable cells
Which of the following is not a disadvantage of the direct microscopic count?
A) Some organisms are motile.
B) Enumerates dead cells.
C) No incubation time.
D) Sample volume is unknown.
E) Large number of cells is required. - correct answer Sample volume is unknown
Which of the following is not used to determine metabolic activity?
A) Acid production from fermentation.
B) CO 2 produced from the Krebs cycle.
C) NO2- produced from the electron transport chain.
D) Decreased dissolved oxygen.
E) Turbidity. - correct answer Turbidity
Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate
count. How many cells were in the original sample?
A) 4
B) 9
C) 18
D) 36
E) 72 - correct answer 72
, Microbiology Chapter 6 test bank
Most bacteria grow best at pH
A) 1.
B) 5.
C) 7.
D) 9.
E) 14. - correct answer 7
Figure 6.3 shows three containers of water connected by tubes. A selectively permeable
membrane divides each tube. Solutes are added to each container to give final concentrations
of 5% NaCl in a; 10% NaCl in b; and 5% sucrose in c. When the experiment is first set up, the
initial movement of water will be
A) a to b; b to c; c to a.
B) a to b; c to b; c to a.
C) a to c; b to c; c to a.
D) a to c; c to b; c to a.
E) b to a; b to c; c to a. - correct answer a to b; c to b; c to a
A culture medium on which only gram-positive organisms grow and a yellow halo surrounds
Staphylococcus aureus colonies is called a(n)
A) Selective medium.
B) Differential medium.
C) Enrichment culture.
D) A and B.
E) B and C. - correct answer A and B
A culture medium consisting of agar, human blood, and beef heart is a
A) Chemically defined medium.
