Question 1

Which of the following best describes the RNA world hypothesis?

Accepted Answer

It proposes a time in evolution when RNA both stored genetic information and catalyzed its own replication.

Question 2

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

Accepted Answer

Fatty acid tail

Question 3

What is the difference between the sugars in DNA and RNA nucleotides?

Accepted Answer

DNA contains deoxyribose with an H at the 2' carbon, while RNA contains ribose with an OH at the 2' carbon.

Question 4

Which of the following nitrogenous bases is found only in RNA and not in DNA?

Accepted Answer

Uracil

Question 5

A phosphodiester linkage in nucleic acids forms between which two groups?

Accepted Answer

The phosphate group on the 5' carbon of one nucleotide and the hydroxyl group on the 3' carbon of another

Question 6

Which equation correctly represents the condensation reaction that forms a phosphodiester bond between two nucleotides?

Accepted Answer

$$\mathrm{Nucleotide}_1 + \mathrm{Nucleotide}_2 \rightarrow \mathrm{Dinucleotide} + \mathrm{H}_2\mathrm{O}$$

Question 7

Why is DNA considered a highly stable molecule compared to RNA?

Accepted Answer

DNA lacks a 2' OH group, making it less reactive and more resistant to degradation.

Question 8

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

Accepted Answer

Adenine pairs with thymine, and guanine pairs with cytosine.

Question 9

What is the directionality of a nucleic acid strand, and how is it conventionally written?

Accepted Answer

It runs from the 5' end to the 3' end and is written as 5'-sequence-3'.

Question 10

Which of the following best explains why activated nucleotides are necessary for nucleic acid polymerization in cells?

Accepted Answer

Activated nucleotides contain two additional phosphate groups, raising their potential energy and making polymerization spontaneous.

Question 11

Which of the following is a real-world example of DNA tertiary structure in eukaryotic cells?

Accepted Answer

DNA wrapping around histone proteins to form nucleosomes

Question 12

During DNA replication, what is the role of complementary base pairing?

Accepted Answer

It allows each strand to be copied exactly, producing two identical daughter molecules.

Question 13

Which of the following features distinguishes RNA secondary structure from DNA secondary structure?

Accepted Answer

RNA secondary structure results from complementary base pairing within the same strand, forming hairpin loops.

Question 14

Which of the following statements about ribozymes is correct?

Accepted Answer

Ribozymes are RNA molecules with three-dimensional structures that enable them to catalyze chemical reactions.

Question 15

Which of the following is a plausible explanation for why RNA is considered to have preceded proteins in the evolution of life?

Accepted Answer

Modern ribozymes are required for protein production, and without them, proteins could not be made.

Question 16

Which of the following equations represents the hydrolysis of a phosphodiester bond in DNA?

Accepted Answer

$$\mathrm{DNA} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{Nucleotides}$$

Question 17

A scientist isolates a nucleic acid molecule that contains uracil, is single-stranded, and folds into complex three-dimensional shapes. What is the most likely identity of this molecule?

Accepted Answer

RNA

Question 18

Which of the following is a key requirement for the first self-replicating molecule according to the theory of chemical evolution?

Accepted Answer

It must provide a template that can be copied and polymerize monomers into a copy of that template.

Question 19

Which of the following best explains the importance of the major and minor grooves in the DNA double helix?

Accepted Answer

They provide sites for protein binding and regulation of gene expression.

Nucleic Acids: Structure, Function, and Evolution

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