Kral, Microbiology Exam #3 (Pearson Questions)

To be supplemented by the three previous exams provided by Dr. Kral.

What is the initial effect of ionizing radiation on a cell?

It causes the formation of highly reactive ions.

What are the methods by which genetic change can occur in bacteria?

Conjugation, transformation, transduction, and mutation.

What is transformation in the context of bacteria?

The transfer of DNA from a donor to a recipient cell as naked DNA in solution.

What does biotechnology involve?

The use of microorganisms to make desired products, the use of animal cells to make vaccines, and the development of disease-resistant crop plants.

What is an advantage of using E. coli to make a human gene product?

Its genes are well known.

What do restriction enzymes do?

They function as bacterial enzymes that destroy phage DNA.

What is the most accurate term for an agent used to reduce the number of bacteria on a toilet?

Disinfectant.

Which pair of terms is mismatched: bacteriostatic or kills vegetative bacterial cells?

Bacteriostatic – kills vegetative bacterial cells.

Which statement regarding antimicrobial control agents is FALSE?

Most chemical agents can achieve sterility.

How long can the most resistant bacterial endospores withstand boiling?

Up to 20 hours.

What can be used to sterilize nutrient agar at home without an autoclave?

Pressure cooker at 121°C for 15 minutes.

What method preserves beef jerky from microbial growth?

Desiccation.

Which of the following is NOT a method of food preservation?

Microwaves.

What can sterilize plastic Petri plates in a plastic wrapper?

Gamma radiation.

Which treatment controls microbial growth most effectively?

They are equivalent treatments.

How does freezing preserve food?

By slowing the metabolic processes of foodborne microbes.

What is a limitation of the autoclave?

It cannot be used with heat-labile materials.

Which method does NOT achieve sterilization?

Pasteurization.

What is the best method to sterilize heat-labile solutions?

Membrane filtration.

What is ethylene oxide?

A sterilizing agent.

What results in lethal damage to nucleic acids?

Heat, radiation, and some chemicals.

What concentration of ethanol is the most effective bactericide?

70 percent.

Which statement regarding Florey and Chain is mismatched?

Identification of Penicillium as the producer of penicillin.

What percentage of antibiotics are produced by bacteria?

More than half.

What are most available antimicrobial agents effective against?

Bacteria.

What happens to a cell in the presence of penicillin?

It undergoes lysis.

Which of the following does NOT affect eukaryotic cells?

Semisynthetic penicillins.

Which organism would MOST likely be sensitive to natural penicillin?

Streptococcus pyogenes.

What type of drug is griseofulvin?

A drug that inhibits mitosis and is more effective against fungi.

What causes drug resistance?

When antibiotics are used indiscriminately.

Which statement about drug resistance is FALSE?

It is found only in gram-negative bacteria.

What can result from washing regularly with antibacterial agents?

Increased susceptibility to disease due to removal of normal microbiota.

What is the major significance of Robert Koch's work?

Microorganisms cause disease.

An enzyme that copies DNA to make a molecule of RNA is:

RNA polymerase

In the figure, if base 4 is adenenine, what is base 11’? (remember complimentary configuration)

Adenine

In the figure, if base 4 is adenine, what is base 4’?

Thymine

What are the products of transcription? What is not?

Products: RNA, mRNA, tRNA, and rRNA.

Not a product: a new strand of DNA

DNA is constructed of:

two strands of nucleotides running in an antiparallel configuration.

A gene is defined as:

a sequence of nucleotides in DNA that codes for a functional product

When ultraviolet light strikes DNA, it can cause a specific type of damage, best described as:

Thymine bases on one strand, next to each other, are covalently linked together to form a thymine dimer. This dimer distorts the DNA structure, leading to replication errors.