Lab Test 1

Question 1

Total magnification = ?

Answer 1

Objective lens magnification * ocular lens magnification

Question 2

Function of condenser lens

Answer 2

Focuses light on specimen

Question 3

Equation for colony-forming units per mL

Answer 3

viable colonies * reciprocal of dilution factor / inoculum amount

Question 4

PEA plate

Answer 4

Phenylethyl Alcohol Agar
Undefined
Selective- encourages gram-positive growth, inhibits gram-negative growth

Question 5

MSA plate

Answer 5

Mannitol Salt Agar
Selective- encourages staphylococcus growth
Differential- turns yellow with fermenters like S. aureus that turns media acidic

Question 6

MacConkey agar

Answer 6

Selective - gram-positive growth inhibited

Differential - turns red with fermentation, becoming acidic (usually enterobacteriacae)

Question 7

EMB plate

Answer 7

Eosin Methylene Blue Agar
Complex
Selective - gram-positive growth inhibited
Differential - E. coli produces a green sheen