Quiz 3

Question 1

Why does microbial growth slow down at their minimum growth temperature?

Answer 1

Microbial growth slows at the minimum growth temperature because the cell’s metabolism slows as well as enzyme activity, transport, and all teh cell’s chemical reactions. The cell membrane becomes gel-like.

Question 2

You have completed a standard plate count and you recorded 152 CFUs on a plate with a 10^-6 dilution factor. 1mL of sample was used to make this Petri dish. What is the number of cells per mL in the initial sample?

Answer 2

1.52 X 10⁸ cells/mL

Question 3

Itis best to administer antibiotics when bacteria are in their _______ stage of growth. Please explain why.

Answer 3

Log phase

Antibiotics are best administered in the log phase because this is when the bacteria are reproducing and there is microbial growth. B-lactams such as penicillian work on growing peptidoglycan layers.

Question 4

You have completed a standard plate count and you recorded 217 CFUs on a plate with a 10^-4 dilution factor. 0.1mL of sample was used to make this petri dish. What is the number of cells per mL in this initial sample?

Answer 4

Question 5

Microbes which grow in cold temperatures are typically referred to as_________.

Answer 5

Psychrophiles

Question 6

Please determine the dilution factors for each container.

Answer 6