Question 1

Which of the following best describes the process by which most bacteria reproduce?

Accepted Answer

Binary fission, where a cell divides into two identical daughter cells.

Question 2

A microbiologist is studying the generation time of a bacterial culture. If the initial cell count is $$N_0 = 1$$ 	imes $$10^3$$ and after 3 hours the cell count is $$N = 8 	imes 10^3$, what is the generation time (g$) in minutes? Use the formula n$$ = \frac{\log N - \log $$N_0$$}{\log 2}$$ and g$$ = \frac{t}{n}$$.

Accepted Answer

$$g = 45$$ minutes

Question 3

Which statement about biofilms is correct?

Accepted Answer

Biofilms are communities of microorganisms attached to a surface and embedded in a self-produced matrix.

Question 4

During which phase of the bacterial growth curve do cells adapt to new conditions but do not divide?

Accepted Answer

Lag phase

Question 5

An organism that requires oxygen for growth but can survive in low oxygen environments is called:

Accepted Answer

Facultative anaerobe

Question 6

Why is superoxide dismutase (SOD) important for aerobic bacteria?

Accepted Answer

It detoxifies superoxide radicals ($$O_2$$^-$$), protecting cells from oxidative damage.

Question 7

Which type of medium would you use to distinguish between two species of bacteria based on their metabolic properties?

Accepted Answer

Differential medium

Question 8

A student counts 50 colonies on a plate after plating 0.1 mL of a 1:10,000 dilution of a bacterial culture. What is the original cell concentration ($$CFU/mL$$)? Use the formula $$CFU/mL = \frac{	ext{Number of colonies}}{	ext{Volume plated} 	imes 	ext{Dilution factor}}.$$

Accepted Answer

$$5 	imes 10^6$ CFU/mL

Question 9

Which cellular macromolecule contains both nitrogen and phosphorus?

Accepted Answer

Nucleic acids

Question 10

Which enzyme is responsible for synthesizing the new DNA strand during bacterial DNA replication?

Accepted Answer

DNA polymerase

Question 11

A mutation that changes a single nucleotide but does not alter the amino acid sequence of a protein is called:

Accepted Answer

Silent mutation

Question 12

The Ames test is primarily used to:

Accepted Answer

Detect the mutagenic potential of chemical compounds.

Question 13

Which of the following is required for bacterial conjugation?

Accepted Answer

A pilus and an F plasmid

Question 14

Transposons are best described as:

Accepted Answer

Segments of DNA that can move from one location to another within a genome.

Question 15

Which statement correctly distinguishes between a repressible and an inducible operon?

Accepted Answer

A repressible operon is usually ON and can be turned OFF by a corepressor, while an inducible operon is usually OFF and can be turned ON by an inducer.

Question 16

Restriction enzymes are used in biotechnology because they:

Accepted Answer

Cut DNA at specific recognition sequences, allowing for precise manipulation of genetic material.

Question 17

Which of the following is NOT a requirement for an ideal cloning vector?

Accepted Answer

It must encode reverse transcriptase.

Question 18

PCR (Polymerase Chain Reaction) is used to:

Accepted Answer

Amplify specific DNA sequences exponentially.

Question 19

Which virus enzyme is responsible for synthesizing DNA from an RNA template, and which type of virus uses it?

Accepted Answer

Reverse transcriptase; retroviruses

Question 20

Lysogenic conversion is medically important because:

Accepted Answer

It can result in bacteria acquiring new virulence factors, such as toxin production.

Microbiology Study Guide: Bacterial Growth, Genetics, Biotechnology, and Viruses

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