Question 1

Which of the following is NOT a necessary property for a molecule to serve as the carrier of genetic information in living organisms?

Accepted Answer

It must be able to code for amino acids plus punctuation.

Question 2

Which of the following correctly describes the difference between a nucleotide and a nucleoside?

Accepted Answer

A nucleoside contains a sugar and a base, while a nucleotide contains a sugar, base, and phosphate.

Question 3

Which of the following is a pyrimidine found only in RNA and not in DNA?

Accepted Answer

Uracil

Question 4

A DNA strand has the sequence 5'-AGCTTCCC-3'. What is the sequence of the complementary strand, written 5' to 3'?

Accepted Answer

5'-CCCTTCGA-3'

Question 5

Which of the following best describes the type of bond that links nucleotides together in a single strand of DNA?

Accepted Answer

Phosphodiester bond

Question 6

What is the main reason that DNA is considered more stable than RNA?

Accepted Answer

DNA lacks the 2' hydroxyl group present in RNA.

Question 7

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

Accepted Answer

Adenine pairs with thymine via two hydrogen bonds.

Question 8

A scientist is analyzing a virus with a genome composed of single-stranded RNA. Which of the following viruses could it be?

Accepted Answer

Coronavirus

Question 9

Which of the following best explains why hydrogen bonds are important in the structure of double-stranded DNA?

Accepted Answer

They allow the two DNA strands to separate easily during replication.

Question 10

Which of the following is the correct chemical formula for a phosphodiester bond as found in DNA?

Accepted Answer

$\mathrm{O{-}P(O_2^-)O{-}C}$

Question 11

If a DNA molecule is described as 'antiparallel,' what does this mean?

Accepted Answer

The two strands run in opposite 5' to 3' directions.

Question 12

Which of the following best describes a dehydration synthesis (condensation) reaction in the context of DNA synthesis?

Accepted Answer

A water molecule is removed to form a phosphodiester bond between nucleotides.

Question 13

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

Accepted Answer

Adenine

Question 14

A mutation replaces a guanine with a thymine in a DNA sequence. Which type of base pairing is disrupted?

Accepted Answer

A purine-pyrimidine pair is replaced with a pyrimidine-pyrimidine pair.

Question 15

Which of the following best explains why DNA is called 'deoxyribonucleic acid'?

Accepted Answer

It contains a ribose sugar lacking an oxygen atom at the 2' position.

Question 16

Which of the following is true regarding the 5' and 3' ends of a DNA strand?

Accepted Answer

The 5' end has a free phosphate group, and the 3' end has a free hydroxyl group.

Question 17

Which of the following best describes the role of hydrogen bonds in the double helix structure of DNA?

Accepted Answer

They hold the two complementary strands together.

Question 18

Which of the following is a real-world example of a genome that consists of double-stranded RNA?

Accepted Answer

Rotavirus

Question 19

A researcher is synthesizing a new DNA strand. Which end of the growing DNA chain does the next nucleotide attach to?

Accepted Answer

The free 3' hydroxyl group

Question 20

Which of the following best explains why a purine always pairs with a pyrimidine in DNA?

Accepted Answer

To maintain a uniform width of the double helix.

DNA and RNA Structure: Foundations of Genetic Information

Study Guide - Practice Questions