Question 1

Which of the following best describes the structural difference between DNA and RNA?

Accepted Answer

DNA contains thymine, while RNA contains uracil.

Question 2

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 3

A mutation changes the codon CGA (arginine) to UGA. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; introduces a premature stop codon

Question 4

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

Accepted Answer

Helicase

Question 5

In eukaryotic cells, which post-transcriptional modification is responsible for removing non-coding regions from pre-mRNA?

Accepted Answer

Splicing by the spliceosome

Question 6

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 7

A bacterial cell acquires a gene for antibiotic resistance from another cell via a sex pilus. What is this process called?

Accepted Answer

Conjugation

Question 8

Which of the following is a function of DNA polymerase during DNA replication?

Accepted Answer

Synthesizing new DNA strands by adding nucleotides

Question 9

Which of the following best describes a plasmid?

Accepted Answer

A small, circular, extrachromosomal DNA molecule in bacteria

Question 10

Which of the following mechanisms allows bacteria to acquire new genetic material from their environment, as demonstrated by Griffith’s experiment?

Accepted Answer

Transformation

Question 11

Which of the following statements about operons is correct?

Accepted Answer

A repressible operon is ON by default and can be turned OFF.

Question 12

Which of the following is a real-life example of a repressible operon?

Accepted Answer

The arginine (arg) operon

Question 13

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

Accepted Answer

It delivers amino acids to the ribosome and matches them to the mRNA codon.

Question 14

Which of the following is a likely consequence of a frameshift mutation?

Accepted Answer

The reading frame is altered, potentially changing every amino acid downstream.

Question 15

Which of the following is a feature of eukaryotic DNA replication that distinguishes it from prokaryotic DNA replication?

Accepted Answer

It initiates at multiple origins of replication.

Question 16

Which of the following best describes the function of excision repair in cells?

Accepted Answer

It removes and replaces damaged or mismatched DNA segments.

Question 17

Which of the following is an example of a biological mutagen?

Accepted Answer

Transposons

Question 18

Which of the following statements about horizontal gene transfer is correct?

Accepted Answer

It allows bacteria to share genes within the same generation.

Question 19

Which of the following best explains why the phenotype of a bacterial cell can change without a change in genotype?

Accepted Answer

Gene expression is regulated in response to environmental conditions.

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

Study Guide - Practice Questions