Exam 6: Microbial Nutrition and Growth

The events of binary fission are I. the cell doubles in size II. the DNA is replicated III. the cell forms a septum IV. the cell separates from its offspring The CORRECT order of these events is

A cell that uses an organic carbon source and obtains energy from light would be called a

Ted heats some food just to boiling, and stores some of it immediately in a container which he places in the refrigerator. A week later he takes the food out and finds it has spoiled. The microbes responsible are probably

Genetic methods of detecting microorganisms reveal that the number of bacterial species in nature exceeds previous estimates by several orders of magnitude. In human mouths, for example, it is estimated that 500-700 microbial species are normally present. Explain why previous estimates were low.

An aquatic microbe that can grow only near the surface of the water is probably which of the following?

A(n) (autotroph/lithotroph/organotroph) uses inorganic molecules as electron donors.

Pure cultures are often obtained by isolating

The (maximum/optimum/selective) growth temperature is the temperature at which an organism exhibits the highest growth rate.

A 0.1 ml sample of a log phase culture contains 10,000 bacterial cells/ml. It is added to 9.9 ml of fresh culture medium broth. Assume a generation time of 30 minutes, and no limiting nutrients. How many bacteria will be present in the entire broth culture after five hours?

A microbiologist inoculates a flask of broth to a concentration of 100 bacterial cells per ml. The generation time of the species is 1 hour, and there is no lag phase. How long will it be before the culture contains more than 6,000 cells per ml?

Which of the following methods provides information about the number of living cells in a sample of bacterial culture?

An epidemiologist is investigating a new disease and observes what appear to be bacteria inside tissue cells in clinical samples from victims. The scientist wants to try to isolate the bacteria in the lab. What culture conditions are most likely to be successful?

Agar is a useful compound in the microbiology lab because it is an excellent nutrient for bacteria.

The only effective way to store bacterial cultures for short periods of time is to arrest their metabolism by freezing.

A fastidious organism might be grown on which of the following types of media?