hmwrk 9 exam review

Death phase

In which phase would you expect to observe the most endospores in a Bacillus cell culture?

Log phase

During which phase would penicillin, an antibiotic that inhibits cell-wall synthesis, be most effective?

Generation time

The length of time it takes for a population of cells to double.

Cell count after five generations

If a culture starts with 50 cells, how many cells will be present after five generations with no cell death? 1600.

Antimicrobial resistance in biofilms

Cells are metabolically inactive at the base of a biofilm.

Quorum sensing

Quorum sensing is used by bacterial cells to determine the density of the population.

Acidophiles

Bacteria that grow in mine drainage at pH 1-2 are probably acidophiles.

Alkaliphiles

Bacteria isolated from Lake Natron, where the water pH is close to 10, are alkaliphiles.

Psychrophile

Psychrophile : Deep ocean waters.

Hyperthermophile

Hyperthermophile : Hydrothermal vent.

Psychrotroph

Psychrotroph : Food spoiling in refrigerator.

Thermophile

Thermophile : Garden compost.

Mesophile

Mesophile : Human pathogen.

Foodborne illness organism

The organism is most likely an obligate or facultative anaerobe, since there should be no oxygen present in the sealed can or bottle.

Enrichment culture

An enrichment culture is used to increase the numbers of a specific organism. It provides conditions to promote its growth and to eventually isolate it.

Selective culture

Selective media inhibit the growth of one type of microorganism while favoring the growth of the microorganism of interest.