Question 1

Which of the following 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 both ribonucleotides and deoxyribonucleotides?

Accepted Answer

A five-carbon sugar

Question 3

What type of bond forms between the phosphate group on the 5' carbon of one nucleotide and the hydroxyl group on the 3' carbon of another nucleotide?

Accepted Answer

Phosphodiester bond

Question 4

Which of the following is a purine base found in nucleic acids?

Accepted Answer

Adenine

Question 5

During DNA replication, which step occurs first?

Accepted Answer

The two DNA strands are separated by breaking hydrogen bonds.

Question 6

Which of the following statements about DNA structure is correct?

Accepted Answer

The sugar–phosphate backbones are on the outside, and the nitrogenous bases are on the inside.

Question 7

Which equation best represents the condensation reaction that forms a phosphodiester bond?

Accepted Answer

$$N_1$$ + $$N_2$$ \rightarrow $$N_1$${-}P{-}O{-}$$N_2 + H_2O$

Question 8

Why is DNA more stable than RNA?

Accepted Answer

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

Question 9

Which of the following best explains why ATP is considered an 'activated nucleotide'?

Accepted Answer

ATP contains three phosphate groups, increasing its potential energy.

Question 10

A mutation causes a DNA molecule to have more supercoiling than normal. Which level of DNA structure is directly affected?

Accepted Answer

Tertiary structure

Question 11

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

Accepted Answer

Adenine pairs with thymine via two hydrogen bonds.

Question 12

Which feature of RNA allows it to act as a catalyst (ribozyme)?

Accepted Answer

Its ability to fold into complex three-dimensional shapes.

Question 13

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

Accepted Answer

DNA forms a double helix, while RNA often forms hairpin loops.

Question 14

Which of the following is a real-life application of complementary base pairing?

Accepted Answer

DNA fingerprinting in forensic science

Question 15

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

Accepted Answer

The 5' end has an unlinked phosphate group, and the 3' end has an unlinked hydroxyl group.

Question 16

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

Accepted Answer

Its sequence of four nitrogenous bases can encode complex information.

Question 17

Which of the following is a correct pairing of a nitrogenous base with the type of nucleic acid in which it is found?

Accepted Answer

Uracil in RNA

Question 18

Which of the following best describes the role of histones in DNA structure?

Accepted Answer

Histones help DNA wrap into compact structures within cells.

Question 19

Which of the following is a plausible consequence if DNA were less stable and more reactive, similar to RNA?

Accepted Answer

Genetic information would be more prone to degradation and mutation.

Question 20

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

Accepted Answer

It ensures that each new DNA molecule is an exact copy of the original.

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

Study Guide - Practice Questions