Question 1

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

Accepted Answer

Genotype is the entire genetic material of an organism, representing its potential properties, while phenotype is the actual expressed properties, such as the collection of proteins.

Question 2

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

Accepted Answer

DNA ligase

Question 3

A mutation that results in the substitution of one base for another, causing a change in a single amino acid in the protein product, is best described as:

Accepted Answer

Missense mutation

Question 4

Which of the following best explains why the genetic code is described as 'degenerate'?

Accepted Answer

Multiple codons can code for the same amino acid.

Question 5

In the lac operon, what is the role of allolactose?

Accepted Answer

It acts as an inducer by inactivating the repressor, allowing transcription.

Question 6

Which process allows bacteria to acquire new genetic material from the environment as 'naked' DNA?

Accepted Answer

Transformation

Question 7

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

Accepted Answer

Insertion or deletion of one or a few nucleotide pairs

Question 8

Which of the following is TRUE regarding plasmids?

Accepted Answer

Plasmids are self-replicating circular DNA molecules that often carry genes for antibiotic resistance.

Question 9

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

Accepted Answer

Helicase

Question 10

In the trp operon, what happens when tryptophan levels are high?

Accepted Answer

Tryptophan acts as a co-repressor, activating the repressor and shutting off transcription.

Question 11

Which of the following best describes the process of transduction in bacteria?

Accepted Answer

Transfer of DNA from a donor to a recipient by way of a bacteriophage

Question 12

Which of the following is a consequence of a nonsense mutation?

Accepted Answer

A stop codon is introduced prematurely, resulting in a truncated protein.

Question 13

Which of the following is a function of the enzyme DNA gyrase during DNA replication?

Accepted Answer

Relaxes supercoils ahead of the replication fork

Question 14

Which of the following statements about operons is correct?

Accepted Answer

An operon includes a promoter, operator, and structural genes.

Question 15

Which of the following best describes the role of the operator in an operon?

Accepted Answer

It is the site where a repressor can bind to regulate transcription.

Question 16

A bacterial cell is exposed to ultraviolet light, resulting in the formation of thymine dimers. Which repair mechanism uses visible light to separate the dimers?

Accepted Answer

Photolyase-mediated light repair

Question 17

Which of the following is TRUE about transposons?

Accepted Answer

Transposons are small segments of DNA that can move from one region of DNA to another.

Question 18

Which of the following equations correctly represents the semiconservative model of DNA replication?

Accepted Answer

$	ext{Parental DNA} ightarrow 	ext{1 Parental Strand} + 	ext{1 Newly Synthesized Strand}$

Question 19

Which of the following best explains why simultaneous transcription and translation can occur in prokaryotes but not in eukaryotes?

Accepted Answer

In prokaryotes, both processes occur in the cytoplasm, while in eukaryotes, transcription occurs in the nucleus and translation in the cytoplasm.

Microbial Genetics: Structure and Function of Genetic Material

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