Question 1

Which of the following best describes the difference between genotype and phenotype in a bacterial cell?

Accepted Answer

Genotype is the genetic makeup encoded in DNA, while phenotype is the expressed properties determined by proteins.

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 a codon from $$	ext{GAA} to$$ $$	ext{GAG}$$, both of which code for glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 4

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

Accepted Answer

The lac operon is induced only when lactose is present and glucose is absent.

Question 5

Which process allows bacteria to take up naked DNA from their environment and incorporate it into their genome?

Accepted Answer

Transformation

Question 6

A scientist exposes bacteria to a chemical and observes an increased rate of histidine prototrophs in the Ames test. What does this suggest about the chemical?

Accepted Answer

It is likely a mutagen and possibly a carcinogen.

Question 7

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

Accepted Answer

To minimize the effects of some mutations.

Question 8

A bacterium acquires a plasmid that carries genes for antibiotic resistance. What is the most likely consequence?

Accepted Answer

The bacterium may survive in the presence of antibiotics that it was previously sensitive to.

Question 9

Which of the following is a key feature of semiconservative DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one parental and one new strand.

Question 10

A frameshift mutation is most likely to result from which of the following genetic changes?

Accepted Answer

An insertion of one nucleotide

Question 11

Which of the following best describes the function of tRNA during translation?

Accepted Answer

tRNA brings specific amino acids to the ribosome by matching its anticodon to the mRNA codon.

Question 12

Which of the following is NOT a function of plasmids in bacteria?

Accepted Answer

Carrying genes essential for normal bacterial survival

Question 13

In the context of gene regulation, what is the role of a repressor protein in the lac operon?

Accepted Answer

It binds to the operator to block RNA polymerase from transcribing the structural genes.

Question 14

Which of the following mechanisms of genetic recombination in bacteria involves a bacteriophage?

Accepted Answer

Transduction

Question 15

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

Accepted Answer

It has a nutritional requirement absent in the parent strain.

Question 16

Which of the following best explains why bacteria are useful for studying mutations?

Accepted Answer

They have only one copy of each gene, so mutations are easily observed.

Question 17

Which of the following statements about transposons is correct?

Accepted Answer

Transposons can move within or between DNA molecules and may carry antibiotic resistance genes.

Question 18

A researcher finds that a bacterial strain can metabolize a new sugar only after exposure to that sugar. This is most likely due to:

Accepted Answer

Gene induction

Question 19

Which of the following is a direct consequence of the complementary base pairing in DNA structure?

Accepted Answer

DNA can be precisely duplicated during cell division.

Question 20

In the absence of glucose, which molecule increases in E. coli to help activate the lac operon?

Accepted Answer

cAMP (cyclic AMP)

Microbial Genetics: Structure, Function, and Mechanisms

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