Prince George Community College » Biology » Bio 2010 - Microbiology » Summer 2022

Question #1

Why do we wait 15 minutes after adding a virus to an E. coli sample before mixing it with warm agar and pouring on an agar plate?

A. To prevent excessive contamination when pouring warm agar on the plate.

B. To allow the 0.5% agar to solidify.

C. To allow the coliphage to come in contact with and infect E. coli cells.

D. To prevent the plates from being too watery.

Question #2

1 ml of a virus culture was added to 9 ml of sterile TSB. What is the final dilution of virus to broth in this tube?

A. 1:100

B. 1:10

C. 1/10,000

D. 1/1000

Question #3

The acronym PFU stands for

A. polyformyl uracil

B. colony-forming unit.

C. pre-formed units

D. plaque-forming unit.

Question #4

Which of the following is a catalase-negative coccus?

A. M. luteus

B. E. durans

C. N. sicca

D. S. epidermidis

Question #5

α hemolysis causes an olive green color that represents.

A. the complete breakdown of blood cells on BAP.

B. citrate utilization on Simmons citrate agar.

C. no breakdown of red blood cells on BAP.

D. the partial breakdown of blood cells on BAP.

Question #6

This compound converts fibrinogen into fibrin in blood plasma.

A. cellulose

B. fibrolysin

C. hemolysin

D. coagulase

Question #7

Which of the following is α hemolytic, sensitive to optochin, resistant to bacitracin and will not grow on bile esculin agar?

A. S. aureus

B. S. pneumoniae

C. E. durans

D. S. pyogenes