Question 1

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

Accepted Answer

DNA is transcribed into mRNA, which is then translated into protein, resulting in cellular function.

Question 2

A mutation that results in the insertion or deletion of a nucleotide pair in a gene is called a:

Accepted Answer

Frameshift mutation

Question 3

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 4

In the lac operon, what happens when lactose is present in the environment?

Accepted Answer

Allolactose binds to the repressor, inactivating it and allowing transcription of the operon.

Question 5

Which of the following statements about bacterial chromosomes is correct?

Accepted Answer

They are usually a single, circular DNA molecule associated with proteins.

Question 6

What is the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand.

Question 7

Which of the following best describes a repressible operon?

Accepted Answer

It is usually on but can be turned off by a corepressor binding to the repressor.

Question 8

A base substitution mutation that results in a stop codon is called a:

Accepted Answer

Nonsense mutation

Question 9

Which of the following is a function of plasmids in bacteria?

Accepted Answer

They may carry genes for antibiotic resistance and can be transferred between cells.

Question 10

During translation, what is the role of tRNA?

Accepted Answer

It brings amino acids to the ribosome and matches them to the mRNA codon via its anticodon.

Question 11

Which of the following best explains why bacterial DNA replication is considered bidirectional?

Accepted Answer

Replication proceeds in both directions from the origin, creating two replication forks.

Question 12

Which of the following is an example of horizontal gene transfer in bacteria?

Accepted Answer

A bacterium acquires an antibiotic resistance gene from another bacterium via conjugation.

Question 13

Which enzyme is responsible for synthesizing RNA primers during DNA replication?

Accepted Answer

Primase

Question 14

A scientist exposes bacteria to UV light, which causes thymine dimers to form. Which enzyme can repair this damage using visible light?

Accepted Answer

Photolyase

Question 15

Which of the following best describes the difference between genotype and phenotype?

Accepted Answer

Genotype is the genetic makeup; phenotype is the expression of those genes.

Question 16

Which of the following is a real-world consequence of bacterial gene alteration?

Accepted Answer

Development of antibiotic resistance in pathogenic bacteria.

Question 17

Which of the following statements about the genetic code is correct?

Accepted Answer

It is degenerate, meaning most amino acids are encoded by more than one codon.

Question 18

A patient is infected with a bacterial strain that can metabolize an unusual compound not found in most environments. Which genetic element is most likely responsible for this ability?

Accepted Answer

A dissimilation plasmid

Question 19

Which of the following best explains the role of natural selection in bacterial evolution?

Accepted Answer

It favors the survival of bacteria with genotypes best suited to the environment, which arise from mutation and recombination.

Question 20

A laboratory strain of E. coli is exposed to a mutagen that causes a base substitution in the gene encoding beta-galactosidase. The resulting protein is nonfunctional. Which type of mutation most likely occurred?

Accepted Answer

Missense mutation

Microbial Genetics: Structure, Function, and Regulation of Genetic Material

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