Question 1

Which of the following best describes the Central Dogma of Molecular Biology?

Accepted Answer

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

Question 2

A DNA molecule contains 17% guanine. What percentage of adenine does it contain?

Accepted Answer

$$33\%$$

Question 3

Which enzyme is responsible for synthesizing short RNA primers during DNA replication?

Accepted Answer

Primase

Question 4

Why does the lagging strand require multiple primers during DNA replication?

Accepted Answer

Because the lagging strand is synthesized discontinuously in short fragments.

Question 5

Which of the following statements about prokaryotic and eukaryotic gene structure is correct?

Accepted Answer

Eukaryotic genes contain introns that must be removed from pre-mRNA.

Question 6

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

Accepted Answer

Eukaryotic mRNA must be exported from the nucleus before translation.

Question 7

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

Accepted Answer

Joins Okazaki fragments on the lagging strand.

Question 8

A mutation occurs during DNA replication. Which enzyme is primarily responsible for correcting mismatched bases?

Accepted Answer

DNA polymerase

Question 9

Which of the following best describes an inducible operon?

Accepted Answer

It is turned on when the substrate inactivates the repressor.

Question 10

In the presence of both glucose and lactose, what is the state of the lac operon in E. coli?

Accepted Answer

It is off because cAMP levels are low and CAP cannot activate transcription.

Question 11

Which of the following is true about the directionality of DNA synthesis?

Accepted Answer

DNA is synthesized in the 5' to 3' direction.

Question 12

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

Accepted Answer

tRNA brings amino acids to the ribosome and matches them to the mRNA codon.

Question 13

A gene is defined as:

Accepted Answer

A segment of DNA that codes for a functional product.

Question 14

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

Accepted Answer

The genetic code is redundant, meaning multiple codons can code for the same amino acid.

Question 15

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

Accepted Answer

RNA is usually single-stranded, while DNA is double-stranded.

Question 16

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

Accepted Answer

Helicase

Question 17

Which of the following best describes catabolite repression in the lac operon?

Accepted Answer

The absence of glucose increases cAMP, which activates CAP and promotes lac operon transcription.

Question 18

Which of the following is NOT a component of a DNA nucleotide?

Accepted Answer

Ribose sugar

Question 19

Which process removes introns from pre-mRNA in eukaryotes?

Accepted Answer

mRNA processing (splicing)

Question 20

Which of the following best explains why prokaryotes can replicate their chromosome in 40 minutes even though their generation time is 20 minutes?

Accepted Answer

They initiate new rounds of replication before the previous round is complete.

Molecular Biology: DNA, RNA, and Gene Regulation in Microbiology

Study Guide - Practice Questions