6 Microbiology

1) In Figure 6.1, which line best depicts a facultative anaerobe in the absence of O2? A) a B) b C) c

3) In Figure 6.1, which line best depicts an obligate anaerobe in the presence of O2? A) a B) b C) c

5) In Figure 6.1, which line shows the growth of an obligate aerobe incubated anaerobically? A) a B) b C) c

6) In Figure 6.1, which line best illustrates the growth of a facultative anaerobe incubated aerobically? A) a B) b C) c

9) In Figure 6.1, which line best depicts a psychrophile incubated at room temperature? A) a B) b C) c

10) In Figure 6.1, which line best depicts a psychrotroph incubated at 0°C? A) a B) b C) c

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

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.

14) The term facultative anaerobe refers to an organism that A) Doesn't 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.

15) Which of the following is an advantage of the standard plate count? A) Can readily count cells that form aggregates B) Requires incubation time C) Determines the number of viable cells D) Chemical and physical requirements are determined by media and incubation. E) Cannot be used to count bacteria in food

16) Which of the following is an advantage of the direct microscopic count? A) Can readily count organisms that are motile B) Enumerates dead cells C) Requires no incubation time D) Sample volume is unknown. E) Requires a large number of cells

17) Which of the following is NOT used to determine metabolic activity? A) Acid production from fermentation B) CO2 produced from the Krebs cycle C) NO2- produced from the electron transport chain D) Decreased dissolved oxygen E) Turbidity

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

19) In Figure 6.2, which section shows a growth phase where the number of cells dying equals the number of cells dividing? A) a B) b C) c D) d E) a and c

20) In Figure 6.2, which sections of the graph illustrate a logarithmic change in cell numbers? A) a and c B) b and d C) a and b D) c and d E) b only

21) Most bacteria grow best at pH A) 1. B) 5. C) 7. D) 9. E) 14.

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) A and B E) B and C

24) A culture medium consisting of agar, human blood, and beef heart is a A) Chemically defined medium. B) Complex medium. C) Selective medium. D) Differential medium. E) Reducing medium.

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 100°C

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.

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 division

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

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

34) In Figure 6.4, in which tube are microaerophiles growing? A) a B) b C) c D) d E) e

35) In Figure 6.4, in which tube are facultative anaerobes growing? A) a B) b C) c D) d E) e

MgSO4 KH2PO4 (NH4)2SO4 CaCl2 MgSO4 KH2PO2 NaHCO3 (NH4)2SO4 Na2HPO4 37) In Table 6.1, which medium (media) is (are) chemically defined? A) A B) B C) C D) A and B E) A and C

MgSO4 KH2PO4 (NH4)2SO4 CaCl2 MgSO4 KH2PO2 NaHCO3 (NH4)2SO4 Na2HPO4 38) In Table, 6.1, in which medium would an autotroph grow? A) A B) B C) C D) A and B E) A and C

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) The same number of cells in both.

40) The source of nutrients in nutrient agar is A) Agar. B) Nutrient. C) Peptone and beef extract. D) Peptone and NaCl. E) All of the above.

41) Which enzyme catalyzes the reaction: O2- + O2- + 2H+ → H2O2 + O2? A) Catalase B) Oxidase C) Peroxidase D) Superoxide dismutase

42) Which enzyme catalyzes the reaction: 2H2O2 → 2H2O + O2? A) Catalase B) Oxidase C) Peroxidase D) Superoxide dismutase

43) Which enzyme catalyzes the reaction: H2O2 + 2H+ → 2H2O? A) Catalase B) Oxidase C) Peroxidase D) Superoxide dismutase

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.

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 cause infections.