Question

in a standard plate count, what range of colonies is considered countable?
500 - 1000
30 - 300
1 - 10
any number of colonies
question 12 (1 point)
mannitol salt agar (msa) is selective for which bacterial genus?
proteus
pseudomonas
escherichia
streptococcus

Explanation:

In a standard plate count, plates with 30 - 300 colonies are considered countable as fewer than 30 may lead to statistically unreliable results and more than 300 are too difficult to count accurately. Mannitol Salt Agar (MSA) is selective for Staphylococcus bacteria due to its high salt concentration and mannitol - fermentation properties. Among the given options, Staphylococcus is not present but the closest in concept for MSA selectivity is related to the general idea of halotolerant bacteria which Staphylococcus is a part of.

Answer:

Question 11: B. 30 - 300
Question 12: None of the above (but conceptually related to Staphylococcus - like halotolerant bacteria)