Question 1

Which experiment provided the first evidence that DNA, not protein, is the genetic material responsible for heredity in bacteria?

Accepted Answer

Hershey-Chase experiment using bacteriophages and radioactive labeling

Question 2

In the Hershey-Chase experiment, which radioactive label was found inside the bacterial cells after infection by bacteriophage?

Accepted Answer

Radioactive phosphorus ($$^{32}P)$$

Question 3

According to Chargaff’s rules, if a DNA sample contains 22% guanine, what percentage of adenine would you expect to find?

Accepted Answer

28%

Question 4

Which scientist(s) used X-ray diffraction to help reveal the double helix structure of DNA?

Accepted Answer

Franklin

Question 5

What is the significance of the antiparallel arrangement of DNA strands in the double helix?

Accepted Answer

It permits complementary base pairing

Question 6

During DNA replication, which enzyme relieves the strain caused by the unwinding of the double helix?

Accepted Answer

Topoisomerase

Question 7

Which of the following statements correctly describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

Question 8

What is the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments together on the lagging strand.

Question 9

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

Accepted Answer

DNA → RNA → Protein

Question 10

Which of the following processes is responsible for the synthesis of an RNA molecule from a DNA template?

Accepted Answer

Transcription

Question 11

Which type of RNA carries amino acids to the ribosome during translation?

Accepted Answer

tRNA

Question 12

What is the role of the sigma (σ) factor in prokaryotic transcription?

Accepted Answer

It allows RNA polymerase to recognize the promoter sequence.

Question 13

Which of the following is a characteristic of polycistronic mRNA?

Accepted Answer

It carries multiple genes on a single mRNA strand.

Question 14

Which of the following statements about the lac operon is TRUE?

Accepted Answer

It is an inducible operon that is normally turned off.

Question 15

How does glucose inhibit transcription of the lac operon in E. coli?

Accepted Answer

By reducing the levels of intracellular cAMP.

Question 16

Which of the following is a function of the CRISPR-Cas system in bacteria?

Accepted Answer

It acts as a bacterial defense mechanism against viral infections.

Question 17

Which of the following is NOT a type of horizontal gene transfer in bacteria?

Accepted Answer

Transamination

Question 18

What is the main difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction transfers any bacterial gene, while specialized transduction transfers only specific genes adjacent to the prophage.

Question 19

Which enzyme is responsible for catalyzing the insertion of a transposon into a new location in the genome?

Accepted Answer

Transposase

Question 20

Which DNA repair mechanism is most likely to fix a thymine dimer caused by UV light?

Accepted Answer

Nucleotide excision repair

Microbial Genetics: Foundations, Experiments, and Molecular Mechanisms

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