Question 1

Which of the following best describes the function of DNA in all organisms?

Accepted Answer

DNA functions as the genetic material, carrying the genetic complement of all organisms and many viruses.

Question 2

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to a pre-existing primer?

Accepted Answer

DNA polymerase

Question 3

In prokaryotic cells, where does DNA replication begin?

Accepted Answer

At a specific site called the origin of replication

Question 4

Which of the following statements about the directionality of DNA synthesis is correct?

Accepted Answer

DNA synthesis occurs in the 5' to 3' direction on both the leading and lagging strands.

Question 5

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5' to 3' direction, so the lagging strand is synthesized discontinuously.

Question 6

A mutation occurs in a bacterial cell that disables the function of DNA ligase. What is the most likely consequence during DNA replication?

Accepted Answer

The cell will be unable to join Okazaki fragments on the lagging strand, resulting in incomplete DNA synthesis.

Question 7

Which of the following is NOT a difference between prokaryotic and eukaryotic genomes?

Accepted Answer

Prokaryotic genomes have multiple origins of replication, while eukaryotic genomes have only one.

Question 8

During transcription in prokaryotes, what is the role of the sigma factor?

Accepted Answer

It recognizes and binds to the promoter sequence, allowing RNA polymerase to initiate transcription.

Question 9

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is replicated, transcribed into RNA, and RNA is translated into protein.

Question 10

A scientist is studying a gene that is only expressed when a specific sugar is present in the environment. Which of the following best explains this phenomenon?

Accepted Answer

The gene is regulated and its expression results from the presence of the sugar, which acts as an inducer.

Question 11

Which of the following correctly matches the process with its main function?

Accepted Answer

Transcription: Copying DNA information into RNA

Question 12

Which of the following statements about the structure of nucleic acids is correct?

Accepted Answer

Nucleic acids are polymers of nucleotides linked by phosphodiester bonds between the 5' phosphate and 3' hydroxyl groups.

Question 13

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

Accepted Answer

tRNA carries amino acids to the ribosome and matches them to the codons in mRNA via its anticodon.

Question 14

A mutation changes a codon from UAU (tyrosine) to UAA. What is the most likely effect on the resulting protein?

Accepted Answer

The protein will be truncated because UAA is a stop codon, leading to premature termination of translation.

Question 15

Which of the following equations correctly represents the directionality of DNA synthesis?

Accepted Answer

$$5' \rightarrow 3'$$

Question 16

During the elongation phase of transcription, which of the following occurs?

Accepted Answer

RNA polymerase synthesizes a complementary RNA strand using the DNA template.

Question 17

Which of the following is a key difference between DNA replication and transcription?

Accepted Answer

Replication copies the entire genome, while transcription copies only specific genes.

Question 18

A bacterial cell is exposed to a chemical that inhibits primase. What is the most likely effect on DNA replication?

Accepted Answer

The cell will be unable to synthesize RNA primers, preventing DNA polymerase from initiating DNA synthesis.

Question 19

Which of the following best describes the role of the promoter in transcription?

Accepted Answer

It is the DNA sequence recognized by RNA polymerase to initiate transcription.

Question 20

Which of the following statements about the genetic code is correct?

Accepted Answer

The genetic code is redundant, meaning that most amino acids are specified by more than one codon.

Microbial Genetics: DNA Structure, Replication, Transcription, and Translation

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