Question 1

Which of the following best explains why DNA replication is considered 'semiconservative'?

Accepted Answer

Each new DNA molecule consists of one original strand and one newly synthesized strand.

Question 2

During DNA replication, which enzyme is primarily responsible for synthesizing the new DNA strand by adding nucleotides to the 3' end?

Accepted Answer

DNA polymerase

Question 3

A scientist is comparing the genomes of a prokaryote and a eukaryote. Which of the following statements is most accurate regarding the number of genes and genome size?

Accepted Answer

Eukaryotes generally have larger genomes and more genes than prokaryotes.

Question 4

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

Accepted Answer

It brings specific amino acids to the ribosome based on the codon sequence of mRNA.

Question 5

A mutation changes a codon from $	ext{UAC}$ (tyrosine) to $	ext{UAA}$ (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 6

Which of the following is a key difference between the cell walls of bacteria and archaea?

Accepted Answer

Bacterial cell walls contain peptidoglycan, while archaeal cell walls do not.

Question 7

Which of the following best describes horizontal gene transfer in bacteria?

Accepted Answer

The movement of genetic material between organisms other than by vertical transmission from parent to offspring.

Question 8

A researcher is studying a virus that can only replicate inside a living host cell. What term best describes this virus?

Accepted Answer

Obligate intracellular parasite

Question 9

Which of the following best explains the difference between the lytic and lysogenic cycles of a bacteriophage?

Accepted Answer

The lytic cycle results in immediate destruction of the host cell, while the lysogenic cycle integrates the phage genome into the host genome.

Question 10

Which of the following best describes the function of the promoter region in DNA transcription?

Accepted Answer

It is the site where RNA polymerase binds to initiate transcription.

Question 11

A patient is infected with a bacterium that can survive in extreme environments such as hot springs and high-salt lakes. Which group is this organism most likely to belong to?

Accepted Answer

Archaea

Question 12

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The two strands are held together by hydrogen bonds between complementary base pairs.

Question 13

Which of the following is a real-world example of horizontal gene transfer?

Accepted Answer

A bacterium acquiring antibiotic resistance genes from another bacterium via conjugation.

Question 14

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that results in a different amino acid being incorporated into the protein.

Question 15

Which of the following is a function of rRNA in the cell?

Accepted Answer

It forms the structural and catalytic core of the ribosome.

Question 16

A scientist is using 16S rRNA gene sequencing to classify a newly discovered microorganism. What is the main advantage of this method over classification by visual characteristics?

Accepted Answer

It provides more accurate phylogenetic relationships based on genetic information.

Question 17

Which of the following best describes the role of the start codon in translation?

Accepted Answer

It signals the ribosome where to begin translating the mRNA into protein.

Question 18

Which of the following is a key feature of the Griffith's experiment that demonstrated transformation in bacteria?

Accepted Answer

Non-virulent bacteria became virulent after exposure to heat-killed virulent bacteria.

Question 19

Which of the following best explains why viruses are considered obligate intracellular parasites?

Accepted Answer

They require a host cell's machinery to replicate their genetic material and produce new viruses.

Question 20

A mutation in a gene does not change the amino acid sequence of the resulting protein. What type of mutation is this?

Accepted Answer

Silent mutation

Microbiology Study Guide: DNA, Genetics, Phylogeny, and Viruses

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