Test #3 Sample Test A

1. If a single bacterium replicated every 20 minutes, how many bacteria would be present in 2 hours?
a. 16
b. 32
c. 128
d. 4
e. 64
2. In which phase of the growth curve is the change in microbial population slowest or the least?
a. death phase
b. logarithmic decline phase
c. stationary phase
d. log phase
e. lag phase
3. During the lag phase:
a. cells are engaged in intense enzymatic activity
b. nutrients are depleted
c. cells are decreasing in number
d. changes in pH occur
e. cells are growing in number
4. The most likely means of reducing bacterial concentrations while NOT affecting the flavor of a pulpy fruit drink would be which of the following?
a. filtration
b. pasteurization
c. autoclaving
d. addition of benzoic acid
e. chlorination
5. Which of the following would be the fastest way to measure bacterial growth?
a. differential plate counts
b. turbidity
c. change in dry weight
d. assay of an enzyme in the media
e. most probable number
6. Trace elements are added to microbiological media to provide which of the following?
a. osmotic pressure
b. reducing agents
c. enzyme cofactors
d. energy
e. buffers
7. An unknown culture is assayed via the plate count method. After dilution of cells and incubation, no colonies are observed. Which of the following is not a possible explanation?
a. There were no cells in the culture
b. The media did not support the growth of the microbes
c. The wrong dilution was plated
d. The bacterial cells formed invisible colonies
e. The incubation conditions were incorrect
8. Which of the following is not a chemical requirement of ALL bacteria?
a. nitrogen
b. molecular oxygen (O2)
c. mineral elements
d. sulfur
e. carbon
9. Superoxide dismutase neutralizes which form of toxic oxygen?
a. hydrogen superoxide
b. peroxide anion
c. superoxide free radicals
d. superoxide anions
e. singlet oxygen
10. An organism that grows only in the presence of oxygen is called which of the following?
a. obligate aerobe
b. microaerophile
c. obligate anaerobe
d. aerotolerant anaerobe
e. facultative anaerobe
11. Bacteria require nitrogen for the synthesis of which of the following?
a. fatty acids
b. lipids
c. carbohydrates
d. sugars
e. proteins
12. Hydrogen peroxide is often a byproduct of biochemical reactions. Which enzyme "disposes" of hydrogen peroxide in cells thereby reducing its toxicity?
a. pyruvate kinase
b. ATP synthase
c. superoxide dismutase
d. catalase
e. lysozyme
13. A culture medium consisting of agar, peptone and beef heart extract would be considered which of the following?
a. a selective medium
b. a differential medium
c. an enrichment medium
d. a complex medium
e. a chemically defined medium
14. Which of the following is NOT a component of a defined media?
a. magnesium chloride
b. potassium nitrate
c. soy tryptone
d. ammonium sulfate
e. glucose
15. Which of the following would NOT be considered a toxic form of oygen?
a. hydrogen peroxide
b. peroxide anion
c. superoxide free radicals
d. molecular oxygen
e. singlet oxygen
16. Which of the following types of media is designed to suppress the growth of unwanted bacteria and encourage the growth of desired microbes?
a. enriched media
b. nutrient agar
c. differential media
d. selective media
e. defined media
17. Blood agar used to observe hemolysis or clearing around Streptococcus pyogenes colonies is an example of which of the following?
a. differential media
b. enrichment media
c. isolation media
d. selective media
e. reducing media
18. Sterilization is defined as which of the following?
a. same as sanitization
b. destruction of all forms of microbial life except endospores
c. destruction of all life forms
d. control of all microbial growth
e. effective removal of all microbes on a surface
19. The first disinfectant used by Lister was
a. iodine
b. chlorine
c. Listerine
d. Betadine
e. phenol
20. Which of the following is not an oxidizing agent?
a. ozone
b. bleach
c. iodine
d. phenol
e. hydrogen peroxide