Question: d

Answer: 1. 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.

Question: c

Answer: 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.

Question: c

Answer: 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.

Question: e

Answer: 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.

Question: d

Answer: 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

Question: b

Answer: A culture medium consisting of agar, human blood, and beef heart is a: a. chemically defined mediumb. complex mediumc. selective medium d. differential medium e. reducing medium

Question: d

Answer: Which of the following pairs is mismatched? a. psychrotroph - growth at 0 degrees C b. thermophile - growth at 37 degrees Cc. mesophile - growth at 25 degrees C d. psychrophile - growth at 15 degrees C e. non of the above

Question: b

Answer: 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

Question: b

Answer: Which of the following is the best definition of generation time? a. The length of time it takes for lag phase. b. The length of time it takes for a cell to divide. c. The minimum rate of doubling. d. The duration of log phase. e. The time it takes for nuclear division.

Question: e

Answer: Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt? a. Psychrophiles b. Halophiles c. Anaerobes d. Thermophiles e. None of the above

Question: a

Answer: Which organism produces catalase and superoxide dismutase? a. Aerobe b. Aerotolerant anaerobe c. Obligate anaerobe d. None of the above

Question: c

Answer: Which organism is killed by atmospheric O2? a. Aerobe b. Aerotolerant anaerobe c. Obligate anaerobe

Question: a

Answer: Which of the following types of microbes can grow below refrigerator temperatures? a. Psychrophiles b. Psychrotrophs c. Mesophiles d. Thermophiles e. Hyperthermophiles

Question: b

Answer: You have found an organism that can live both with and without Oxygen. Which of the following categories does it belong in? a. Obligate aerobes b. Facultative anaerobes c. Obligate anaerobes d. Aerotolerant anaerobes e. Microaerophiles

Question: b

Answer: Which of the following recipes for bacterial media would be classified as Complex Media? a. Glucose 9.1g, Potassium 12.2g, Arginine 1.2g, Starch 9.1g, Biotin 0.5gb. Beef extract 3g, Yeast extract 2.5g, Sodium chloride 8g

Question: c

Answer: You have placed a streaked a bacteria on an unlabeled agar plate and found that the colonies were a blue color the next day (instead of their normal white color). What can you say about the agar plate? a. It was contaminated b. It was selective media c. It was differential media d. The media is fine, the bacteria are just angry and holding their breath