Q: Which of the following is the correct sequence of steps in the Polymerase Chain Reaction (PCR)?

Denaturation $$\to$$ Annealing $$\to$$ Extension

Question 1

Which of the following best describes the outcome of Griffith’s experiment with Streptococcus pneumoniae in mice?

Accepted Answer

Live non-virulent bacteria transformed into virulent bacteria when mixed with heat-killed virulent bacteria, killing the mice.

Question 2

Which experiment provided the most direct evidence that DNA, and not protein, is the genetic material in bacteriophages?

Accepted Answer

Hershey and Chase’s experiment using radioactive isotopes

Question 3

Which of the following is NOT a chemical component of DNA?

Accepted Answer

Uracil base

Question 4

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

$$DNA 	o RNA 	o Protein$$

Question 5

During transcription in prokaryotes, what is the primary function of the sigma ($$\sigma) $$factor?

Accepted Answer

It recognizes and binds to the promoter region to initiate transcription.

Question 6

Which of the following statements about the wobble hypothesis is correct?

Accepted Answer

It allows a single tRNA to recognize multiple codons due to flexible base pairing at the third codon position.

Question 7

Which of the following best describes the difference between factor-independent and Rho-dependent termination of transcription in bacteria?

Accepted Answer

Factor-independent termination relies on a GC-rich hairpin loop followed by a poly-U sequence, while Rho-dependent termination requires the Rho protein to dissociate the RNA transcript.

Question 8

Which of the following is the correct sequence of steps in the Polymerase Chain Reaction (PCR)?

Accepted Answer

Denaturation $$	o$$ Annealing $$	o$$ Extension

Question 9

A scientist wants to verify the size of a PCR product. Which technique should they use?

Accepted Answer

Gel electrophoresis

Question 10

Which of the following is an example of mutualism?

Accepted Answer

Buchnera aphidicola providing essential amino acids to aphids, while receiving nutrients in return

Question 11

Which of the following best distinguishes commensalism from amensalism?

Accepted Answer

In commensalism, one organism benefits and the other is unaffected; in amensalism, one is harmed and the other is unaffected.

Question 12

Which of the following is a correct example of predation in microbial interactions?

Accepted Answer

Bdellovibrio bacteriovorus invading and consuming other bacteria

Question 13

Which of the following best describes the term 'holobiont'?

Accepted Answer

A host organism and all of its associated microorganisms considered as a single ecological unit

Question 14

Which of the following is NOT a route by which gut microbes communicate with the central nervous system (CNS)?

Accepted Answer

Direct electrical synapses between gut bacteria and neurons

Question 15

Which of the following best defines 'prevalence rate' in epidemiology?

Accepted Answer

The total number of cases (new and existing) of a disease in a population at a given time, divided by the total population

Question 16

Which of the following best describes 'herd immunity'?

Accepted Answer

Protection of susceptible individuals in a population when a sufficient proportion is immune, reducing disease spread

Question 17

Which of the following is a key reason for the increase in emerging and reemerging infectious diseases?

Accepted Answer

Antibiotic resistance due to overuse and misuse of antibiotics

Question 18

Which of the following best describes antigenic shift?

Accepted Answer

A sudden, major change in a virus’s genome due to reassortment of genetic material

Question 19

Which of the following is a correct example of a propagated epidemic?

Accepted Answer

A disease spreading person-to-person over several weeks in a community

Question 20

Which of the following best describes a probiotic?

Accepted Answer

A live microorganism that, when administered in adequate amounts, confers a health benefit to the host

Microbiology Exam 2 Study Guide: Bacterial Genome, Microbial Interactions, PCR, Microbiome, and Epidemiology

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