Medical Quiz

Microbial Growth Quiz


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The stage in population growth with the highest rate of cell division is the

A. stationary phase

B. lag phase

C. exponential phase

D. enlargement phase


Which group of organisms is most likely to infect humans

A. psychrophiles

B. mesophiles

C. thermophiles

D. hyperthermophiles


In which phase is the bacteria most metabolically active?

A. Lag Phase

B. Log Phase

C. Exponential Phase

D. Death phase


In which environment are you most likely to encounter an acidophile?

A. human blood at pH 7.2

B. a hot vent at pH 1.5

C. human intestine at pH 8.5

D. milk at pH 6.5


Which statement is correct?

A. Archea have internal membrane- bound

B. Most yeasts reproduce by budding

C. Fungi are photosynthetic microorganisms

D. Bacteria need lower moisture content to grow than molds


Extremely high temperatures can cause a decline in bacterial growth because

A. heat increases metabolic rate and creates more waste products.

B. heat slows down metabolic rate.

C. heat denatures enzymes/proteins, DNA, and causes leaky membranes.

D. heat prevents DNA from replicating.


Which of the following is the reason jams and dried meats often do not require refrigeration to prevent spoilage?

A. low pH

B. toxic alkaline chemicals

C. naturally occurring antibiotics

D. low water activity


The optimum temperature where most bacteria can survive

A. 31-40

B. 30-37

C. 31-41

D. 30-39


____ are able to grow at very low pH

A. Acidophiles

B. Alkaliphiles

C. Neutrophiles

D. Halophiles


A soup container was forgotten in the refrigerator and shows contamination. The contaminants are probably which of the following?

A. thermophiles

B. acidophiles

C. mesophiles

D. psychrotrophs


During the stationary phase, bacteria are

A. dying at a faster rate than reproduction.

B. doubling in number every generation.

C. reproducing at the same rate as they are dying.

D. making proteins, ribosomes, and obtaining nutrients.


Which term best describes a bacteria that cannot exist in the presence of oxygen?

A. Obligate aerobe

B. Facultative aerobe

C. Obligate anaerobe

D. Facultative anaerobe


pH requirement for molds and yeast?

A. 6.5-7.5

B. 5-6

C. 7-8

D. 3


Prokaryotes do not have

A. DNA

B. cell walls

C. membrane bound organelles

D. ribosomes


Which of the following is the best definition of generation time in a bacterium?

A. the length of time it takes to reach the log phase

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

C. the time it takes to reach stationary phase

D. the length of time of the exponential phase


Which is the following the main requirement(s) for the bacteria to grow ?

A. Nutrient requirement

B. Oxygen requirement

C. Oxygen and nutrient requirement

D. Physical and chemical requirement


These microorganisma can grow at a temperature range of 10 to 50 oC

A. psychrophiles

B. psychrotrophs

C. mesophiles

D. thermophiles


During the Lag Phase, bacteria are

A. doubling the number of cells every generation.

B. creating new cells at the same rate as cells are dying.

C. making proteins, ribosomes, obtaining nutrients.

D. dying at a faster rate than they are being produced.


E. coli undergoes binary fission approximately every 20 minutes. If a culture started with 1000 cells, how many cells would be there be after 3 hours? (Given Nt=Ni x 2n)

A. 1000 x 29

B. 1000 x 23

C. 20 x 21000

D. 20 x 23


What compound has the highest concentration in a cell?

A. CH4

B. CO2

C. H2O

D. glucose




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