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10 Cards in this Set
- Front
- Back
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The addition of which of the following to a culture medium will neutralize acids?
A) Buffers B) Sugars C) pH D) Heat E) Carbon |
A. Buffers
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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. |
D. Hypertonic environment
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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. |
C. Uses oxygen or grows without oxygen
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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 |
C. Determines the number of viable cells
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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 |
C. requires no incubation time
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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 |
E. Turbidity
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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 |
D. 36
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Most bacteria grow best at pH
A) 1. B) 5. C) 7. D) 9. E) 14. |
C. 7
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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 |
D. A and B
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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 |
B. complex medium
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