$$\text{Nucleotide}_1 + \text{Nucleotide}_2 \rightarrow \text{Dinucleotide} + H_2O$$

Question 1

Which of the following statements best describes the RNA world hypothesis?

Accepted Answer

RNA was the first molecule to store genetic information and catalyze its own replication.

Question 2

Which component is found in all nucleotides?

Accepted Answer

A phosphate group, a five-carbon sugar, and a nitrogenous base

Question 3

Which of the following best explains why DNA is more stable than RNA?

Accepted Answer

DNA contains deoxyribose, which lacks a hydroxyl group at the 2' carbon, making it less reactive.

Question 4

Which of the following is a purine found in both DNA and RNA?

Accepted Answer

Adenine

Question 5

What type of bond forms between the phosphate group of one nucleotide and the hydroxyl group on the sugar of another nucleotide?

Accepted Answer

Phosphodiester bond

Question 6

Which of the following best describes the directionality of a nucleic acid strand?

Accepted Answer

It has a 5' phosphate group at one end and a 3' hydroxyl group at the other.

Question 7

Which of the following equations correctly represents the condensation reaction that forms a phosphodiester bond?

Accepted Answer

$$	ext{Nucleotide}_1 + 	ext{Nucleotide}_2 ightarrow 	ext{Dinucleotide} + H_2O$$

Question 8

Which of the following is true about complementary base pairing in DNA?

Accepted Answer

Adenine pairs with thymine via two hydrogen bonds, and cytosine pairs with guanine via three hydrogen bonds.

Question 9

Which of the following best explains why DNA is an effective molecule for information storage?

Accepted Answer

Its sequence of four nitrogenous bases can encode vast amounts of information.

Question 10

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

Accepted Answer

DNA forms a double helix, while RNA often forms hairpin loops due to intramolecular base pairing.

Question 11

Which of the following best describes the role of ribozymes in the RNA world hypothesis?

Accepted Answer

They catalyzed reactions necessary for RNA replication and nucleotide synthesis.

Question 12

Which of the following is a plausible reason why DNA, rather than RNA, became the primary genetic material in modern cells?

Accepted Answer

DNA is more chemically stable due to the absence of a 2' hydroxyl group.

Question 13

Which of the following best describes the tertiary structure of DNA in eukaryotic cells?

Accepted Answer

DNA is wrapped around histone proteins and can form supercoils.

Question 14

Which of the following is a function of messenger RNA (mRNA) in modern cells?

Accepted Answer

It transmits genetic information from DNA to the protein synthesis machinery.

Question 15

Which of the following best explains why activated nucleotides are required for nucleic acid polymerization?

Accepted Answer

Activated nucleotides have higher potential energy, making the polymerization reaction spontaneous.

Question 16

Which of the following is a correct sequence of events during DNA replication?

Accepted Answer

Strands separate, complementary bases pair, phosphodiester bonds form.

Question 17

Which of the following best describes a real-world application of ribozymes?

Accepted Answer

Ribozymes are used in laboratory settings to catalyze the synthesis of RNA molecules.

Question 18

Which of the following is a key feature of the chemical evolution theory for the origin of life?

Accepted Answer

Life began as a naked self-replicator capable of both templating and polymerizing monomers.

Question 19

Which of the following best explains why complementary base pairing is essential for the accurate replication of DNA?

Accepted Answer

It ensures that each strand can serve as a template to produce an exact copy.

Question 20

Which of the following is a plausible scenario for the evolution of life according to the RNA world hypothesis?

Accepted Answer

RNA molecules capable of self-replication and catalysis gave rise to the first living systems.

Nucleic Acids and an RNA World: Structure, Function, and Evolution

Study Guide - Practice Questions