Lab Quiz 4

Question 1

How do you calculate Original Cell Density?

Answer 1

Colony Forming Units / (Dilution X Volume of sample)

Question 2

What is Beta Hemolysis?

Answer 2

Complete lysis of blood cells

Question 3

What is Alpha Hemolysis?

Answer 3

Partial lysis of blood cells, turns the agar green

Question 4

What is Gamma Hemolysis?

Answer 4

Bacteria can grow on the plate, but can’t destroy any red blood cells

Question 5

When is Blood Agar used in real life?

Answer 5

Strep tests

Question 6

What is bacteriocidal?

Answer 6

Capable of killing bacteria

Question 7

What is bacteriostatic?

Answer 7

Capable of stopping bacterial growth

Question 8

Why doesn’t penicillin kill gram negative bacteria?

Answer 8

Gram negative bacteria have an outer membrane outside of the peptidoglycan that penicillin can not cross.

Question 9

What is a Fomite?

Answer 9

Any object or substance capable of carrying and transferring an infectious disease. Ex: Skin, hair, clothing

Question 10

What is a Vector?

Answer 10

Any agent or person capable of carrying and transferring an infectious disease. Ex: person, mosquito, animal, microorganism

Question 11

What is a Common Source Epidemic?

Answer 11

All victims acquire the infection from the same source like water or ventiliation

Question 12

What is an Index Case?

Answer 12

The first case. The first person to contract the disease.

Question 13

What is Propagated Transmission?

Answer 13

The disease is transferred person to person

Question 14

How do you calculate Incidence Rate?

Answer 14

new diseases in time period / size of at risk population

Question 15

How do you calculate Point Prevalence?

Answer 15

existing cases at a point in time / size of at risk population

Question 16

What is GYEA?

Answer 16

Glycerol Yeast Extract Agar

Question 17

What does GYEA grow?

Answer 17

Actinomycetes bacteria. Actinomycetes are soil decomposers

Question 18

What did the NA select for?

Answer 18

Broad range of bacteria but not fungi

Question 19

What was added to NA to inhibit fungal growth?

Answer 19

Cycloheximide. It blocks eukaryotic biosynthesis

Question 20

What is SDA?

Answer 20

Sobouraund Dextrose Agar

Question 21

What did SDA grow?

Answer 21

Fungi, no bacteria

Question 22

What was aded to SDA to inhibit bacterial growth?

Answer 22

Penicillin and streptomycin

Question 23

What are coliforms?

Answer 23

Lactose fermenting, rod shaped, gram negative bacteria

Question 24

How are coliforms detected on the membrane filter?

Answer 24

Metallic green color

Question 25

What is Endo Agar?

Answer 25

Encourages gram negative growth and inhibits gram positive growth.