Question 1

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

Accepted Answer

Genotype is the genetic makeup of an organism, while phenotype is the expression of those genes as observable traits.

Question 2

During DNA replication in bacteria, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 3

A mutation changes the DNA sequence from $$	ext{TAC} to$$ $$	ext{TAA}. $$Using the genetic code, what type of mutation is this and what is its likely effect?

Accepted Answer

Nonsense mutation; introduces a premature stop codon

Question 4

Which of the following statements about the lac operon in E. coli is correct?

Accepted Answer

The lac operon is induced when lactose binds to the repressor, inactivating it and allowing transcription.

Question 5

Which process describes the transfer of genetic material from one bacterium to another via a bacteriophage?

Accepted Answer

Transduction

Question 6

A bacterial cell is exposed to UV radiation, resulting in the formation of thymine dimers. What is the most likely consequence?

Accepted Answer

Disruption of DNA replication and possible cell death

Question 7

Which of the following best explains why most amino acids are encoded by more than one codon?

Accepted Answer

To minimize the effects of mutations (redundancy in the genetic code)

Question 8

In the process of transcription, which of the following is true?

Accepted Answer

RNA polymerase synthesizes mRNA from a DNA template, starting at the promoter.

Question 9

Which of the following is a characteristic of a frameshift mutation?

Accepted Answer

It alters the reading frame, usually resulting in a nonfunctional protein.

Question 10

A scientist uses the Ames test to evaluate a new chemical. The test shows a high number of revertant colonies compared to the control. What does this indicate?

Accepted Answer

The chemical is likely mutagenic and potentially carcinogenic.

Question 11

Which of the following best describes the function of plasmids in bacteria?

Accepted Answer

They carry non-essential genes that may provide advantages such as antibiotic resistance.

Question 12

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

Accepted Answer

Primase

Question 13

A bacterium is described as an auxotroph. What does this mean?

Accepted Answer

It has a nutritional requirement absent in the parent strain.

Question 14

Which of the following is true about horizontal gene transfer in bacteria?

Accepted Answer

It involves the transfer of genes between cells of the same generation.

Question 15

Which of the following best describes the role of cAMP in the regulation of the lac operon?

Accepted Answer

cAMP binds to the CAP protein, which then enhances RNA polymerase binding to the promoter when glucose is scarce.

Question 16

Which of the following is a real-world example of a beneficial mutation in bacteria?

Accepted Answer

A mutation that allows the bacterium to utilize a new energy source.

Question 17

Which of the following statements about transposons is correct?

Accepted Answer

Transposons are segments of DNA that can move within and between DNA molecules.

Question 18

Which of the following best explains why bacterial gene expression can be regulated at the transcriptional level?

Accepted Answer

Because controlling transcription allows the cell to conserve energy and resources by only producing proteins when needed.

Question 19

A scientist observes that a bacterial cell can no longer synthesize tryptophan after exposure to a mutagen. Which type of operon is most likely affected?

Accepted Answer

Repressible operon

Genetics and Genetic Mechanisms in Microbiology

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