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| 1 | Enterococcus faecalis is a gram positive fecal enterococci. If it were present in the milk samples used in this exercise, which plate(s) would it grow on? |
 | A) | Both the nutrient agar and MacConkey plates |
| B) | Nutrient agar plates |
| C) | MacConkey agar plates |
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| 2 | FDA standards call for counting only plates with between ____ and ____ colonies per plate. |
| A) | 2 and 25 |
| B) | 25 and 250 |
| C) | 250 and 2500 |
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| 3 | What color will the colonies of lactose fermenting bacteria appear when grown on MacConkey agar? |
| A) | Red |
| B) | Pink |
| C) | White |
| D) | Colorless |
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| 4 | Raw milk and pasteurized milk were discussed in this exercise. Ultra pasteurized milk is heated to a higher temperature than regular pasteurized milk. If this same exercise were repeated using raw milk, pasteurized milk and ultra pasteurized milk, think about which type of milk you would predict would have the smallest number of organisms per ml and the largest number of organisms per ml? After diluting the milk samples 1:10, 1:100, and 1:000 and incubating them on nutrient agar plates, which type of milk would you predict to have the most TFTC plates? |
| A) | Raw milk |
| B) | Pasteurized milk |
| C) | Ultra pasteurized milk |
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| 5 | If a student was not being careful to pipette up and down several times between dilutions, (added the 1 mL of milk to the 1:10 sample, then withdrew 1 mL from the 1:10 sample and added it to the 1:100 dilution, then withdrew 1 mL from the 1:100 sample and added it to the 1:1000 dilution), what effect would that have on the dilutions being prepared? |
| A) | The number of organisms per dilution would be artificially high |
| B) | The number of organisms per dilution would be artificially low |