Figure 6.1
1) In Figure 6.1, which line best depicts a facultative anaerobe in the absence of O2?
A) a
B) b
C) c
Answer: B
2) In Figure 6.1 ,which line best depicts an obligate anaerobe in the presence of O2?
A) a
B) b
C) c
Answer: C
3) In Figure 6.1, which line shows the growth of an obligate aerobe incubated anaerobically?
A) a
B) b
C) c
Answer: C
4) In Figure 6.1, which line best illustrates the growth of a facultative anaerobe incubated aerobically?
A) a
B) b
C) c
Answer: A
5) In Figure 6.1, which line best depicts a psychrotroph incubated at 0�C?
A) a
B) b
C) c
Answer: B
6) If cells are grown in media containing amino acids labeled with radioactive nitrogen (15N), most of radioactivity will be found in the cells'
A) DNA.
B) proteins.
C) phospholipids.
D) DNA and proteins.
E) DNA and phospholipids.
Answer: D
7) Which of the following elements is NOT correctly matched with its cellular function?
A) nitrogen � needed for amino acid synthesis
B) phosphorus � incorporated into nucleic acids
C) sulfur � used for synthesis of thiamin and biotin
D) magnesium and pot
Answer: E
8) Pathogenic bacteria isolated from the respiratory or intestinal tracts of humans are
A) strict aerobes that grow best in candle jars.
B) capnophiles that grow best in carbon dioxide incubators.
C) facultative anaerobes that require reducing media for g
Answer: B
9) The biosafety level (BSL) for most introductory microbiology laboratories is
A) BSL-1.
B) BSL-2.
C) BSL-3.
D) BSL-4.
Answer: A
10) The biosafety level (BSL) for a clinical microbiology laboratory working with potentially airborne pathogens, such as tuberculosis bacteria, is
A) BSL-1.
B) BSL-2.
C) BSL-3.
D) BSL-4.
Answer: C
11) A sample of milk is tested for its bacterial content in a plate count assay. A one-milliliter sample of the milk is diluted in a 1:10 dilution series. One milliliter of the third dilution tube is plated in a pour plate. After incubation, the plate has
Answer: D
12) The addition of which of the following to a culture medium will neutralize acids?
A) buffers
B) sugars
C) pH
D) heat
E) carbon
Answer: A
13) 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.
Answer: D
14) The term aerotolerant anaerobe refers to an organism that
A) does not 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) requires more oxygen than is present
Answer: A
15) Which of the following is an advantage of the standard plate count?
A) can readily count cells that form aggregates
B) determines the number of viable cells
C) can be performed on very dilute samples, such as lake water
D) provides immediate results
E
Answer: B
16) Which of the following is an advantage of the direct microscopic count?
A) can readily count organisms that are motile
B) can easily distinguish live from dead cells
C) requires no incubation time
D) sample volume is unknown
E) requires a large number
Answer: C
17) Most bacteria reproduce by
A) aerial hyphae.
B) fragmentation.
C) mitosis.
D) binary fission.
E) budding.
Answer: D
18) 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
Answer: D
Figure 6.2
19) Figure 6.2 shows a typical bacterial growth curve with the x-axis indicating the log of the number of bacteria and the y-axis indicating time in culture. In the figure, which section (or sections) shows a growth phase where the number of ce
Answer: C
20) Figure 6.2 shows a typical bacterial growth curve with the x-axis indicating the log of the number of bacteria and the y-axis indicating time in culture. In the figure, which sections of the graph illustrate a logarithmic change in cell numbers?
A) a
Answer: B
21) Most bacteria grow best at pH
A) 1.
B) 5.
C) 7.
D) 9.
E) 14.
Answer: C
22) Most fungi grow best at pH
A) 1.
B) 5.
C) 7.
D) 9.
E) 14.
Answer: B
23) 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) selective and differential medium.
E) differen
Answer: D
24) A culture medium consisting of agar, peptone, and beef heart is a
A) chemically defined medium.
B) complex medium.
C) selective medium.
D) differential medium.
E) reducing medium.
Answer: B
25) Which of the following pairs is mismatched?
A) psychrotroph � growth at 0�C
B) thermophile � growth at 37�C
C) mesophile � growth at 25�C
D) psychrophile � growth at 15�C
E) hyperthermophiles � growth at 85�C
Answer: B
26) During which growth phase will gram-positive bacteria be most susceptible to penicillin?
A) lag phase
B) log phase
C) death phase
D) stationary phase
E) The culture is equally susceptible during all phases.
Answer: B
27) Which of the following is the best definition of generation time?
A) the length of time needed for lag phase
B) the length of time needed for a cell to divide
C) the minimum rate of doubling
D) the duration of log phase
E) the time needed for nuclear
Answer: B
28) Which of the following is NOT a direct method to measure microbial growth?
A) direct microscopic count
B) standard plate count
C) filtration
D) metabolic activity
E) most probable number (MPN)
Answer: D
29) Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?
A) psychrophiles
B) facultative halophiles
C) anaerobes
D) thermophiles
E) hyperthermophiles
Answer: B
30) Which of the following is an organic growth factor?
A) glucose
B) vitamin B1
C) peptone
D) NH4H2PO4
E) H2O
Answer: B
31) Which of the following is an example of a metabolic activity that could be used to measure microbial growth?
A) standard plate count
B) glucose consumption
C) direct microscopic count
D) turbidity
E) MPN
Answer: B
32) An experiment began with 4 cells and ended with 128 cells. How many generations did the
cells go through?
A) 64
B) 32
C) 6
D) 5
E) 4
Answer: D
33) Three cells with generation times of 60 minutes are inoculated into a culture medium. How many cells are there after 5 hours?
A) 900
B) 180
C) 96
D) 32
E) 15
Answer: C
Figure 6.3
34) In Figure 6.3, which tube shows the expected growth pattern for a microaerophile?
A) a
B) b
C) c
D) d
E) e
Answer: E
35) In Figure 6.3, which tube shows the expected growth pattern for a facultative anaerobe?
A) a
B) b
C) c
D) d
E) e
Answer: B
36) In one hospital, Pseudomonas aeruginosa serotype 10 infected the biliary tract of 10 percent of 1300 patients who underwent gastrointestinal endoscopic procedures. After each use, endoscopes were washed with an automatic reprocessor that flushed deter
Answer: B
Table 6.1
Three different culture media are shown below.
Medium A Medium B Medium C
Na2HPO4 Tide detergent Glucose
KH2PO4 Na2HPO4 Peptone
MgSO4 KH2PO4 (NH4)2SO4
CaCl2 MgSO4 KH2PO2
NaHCO3 (NH4)2SO4 Na2HPO4
37) For the three types of media in Table 6.1, whi
Answer: A
38) In Table, 6.1, in which medium (or media) would an autotroph grow?
A) A
B) B
C) C
D) A and B
E) A and C
Answer: A
39) Assume you inoculated 100 cells into 100 ml of nutrient broth. You then inoculated 100 cells of the same species into 200 ml of nutrient broth. After incubation for 24 hours, you should have
A) more cells in the 100 ml.
B) more cells in the 200 ml.
C)
Answer: C
40) The source of nutrients in nutrient agar is
A) agar.
B) nutrient.
C) peptone and beef extract.
D) peptone and NaCl.
E) agar and NaCl.
Answer: C
41) Which enzyme catalyzes the reaction: O2- + O2- + 2H+ ? H2O2 + O2?
A) catalase
B) oxidase
C) peroxidase
D) superoxide dismutase
Answer: D
42) Which enzyme catalyzes the reaction: 2H2O2 ? 2H2O + O2?
A) catalase
B) oxidase
C) peroxidase
D) superoxide dismutase
Answer: A
43) Which enzyme catalyzes the reaction: H2O2 + 2H+ ? 2H2O?
A) catalase
B) oxidase
C) peroxidase
D) superoxide dismutase
Answer: C
Table 6.2
The following data show growth of two bacteria on different media.
44) The data in Table 6.2 indicate that S. aureus is a(n)
A) mesophile.
B) facultative anaerobe.
C) facultative halophile.
D) aerobe.
E) halophile.
Answer: C
45) Patients with indwelling catheters are susceptible to infections because
A) injected solutions are contaminated.
B) their immune systems are weakened.
C) infections can be transmitted from other people.
D) biofilms develop on catheters.
E) bacteria ca
Answer: D
1) An isolated colony on a streak plate contains millions or billions of identical cells.
Answer: TRUE
2) Bacterial growth refers to an increase in the numbers of cells in a bacterial culture.
Answer: TRUE
3) Pure cultures can easily be obtained on streak plates, even if the desired bacteria are present in very low concentrations.
Answer: FALSE
4) Agar is used as a solidifying agent in microbiological media since few bacteria can degrade it.
Answer: TRUE
5) Laboratory cultivation of obligate anaerobes requires reducing media or special growth chambers filled with inert gases.
Answer: TRUE
6) Most pathogenic bacteria are thermophiles.
Answer: FALSE
7) In performing a ten-fold dilutions series from a sample containing 10,000 bacteria per milliliter, the fourth tube in the dilution series will have 10 cells per milliliter.
Answer: FALSE
8) Turbidity is an indirect measurement of bacterial growth that can be measured using a spectrophotometer.
Answer: TRUE
9) Filtration methods are used to count bacteria present in very low concentrations, such as in lakes and streams.
Answer: TRUE
10) Nitrogen-fixing bacteria, such as cyanobacteria, can use atmospheric nitrogen (N2) for their nitrogen source.
Answer: TRUE