Question 1

Which type of bond connects nucleotides together in the backbone of a DNA molecule?

Accepted Answer

Phosphodiester bond

Question 2

During DNA replication, which base pairs with cytosine?

Accepted Answer

Guanine

Question 3

Which of the following statements best describes complementary base pairing in DNA?

Accepted Answer

Adenine pairs with thymine, and guanine pairs with cytosine.

Question 4

What is the main structural difference between DNA and RNA as shown in the diagrams?

Accepted Answer

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

Question 5

If a DNA strand has the sequence 5'-ATCG-3', what is the complementary sequence on the opposite strand?

Accepted Answer

3'-TAGC-5'

Question 6

Which chemical group is found at the 3' end of a DNA strand?

Accepted Answer

Hydroxyl group

Question 7

Which base is present in RNA but not in DNA?

Accepted Answer

Uracil

Question 8

What type of bond holds the two strands of DNA together?

Accepted Answer

Hydrogen bonds

Question 9

Which of the following best explains why the sequence of one DNA strand determines the sequence of its complementary strand?

Accepted Answer

Base-pairing rules ensure that A pairs with T and G pairs with C.

Question 10

If a DNA molecule contains 30% adenine, what percentage of guanine does it contain?

Accepted Answer

$$20\%$$

Question 11

Which of the following is the correct chemical formula for a phosphodiester bond between two nucleotides?

Accepted Answer

$$\mathrm{C_5$'-O-PO_2$-O-C_3$'}$$

Question 12

Which of the following best describes the backbone of a DNA molecule?

Accepted Answer

Alternating sugar and phosphate groups

Question 13

During transcription, which base in RNA pairs with adenine in DNA?

Accepted Answer

Uracil

Question 14

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

Accepted Answer

Uracil base

Question 15

If a mutation changes a thymine to a cytosine in a DNA strand, what is the most direct effect on the complementary strand?

Accepted Answer

Guanine will pair with cytosine

Question 16

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

Accepted Answer

DNA is double-stranded and contains deoxyribose, making it less susceptible to hydrolysis.

Question 17

Which of the following is the correct directionality of a DNA strand?

Accepted Answer

5' to 3'

Question 18

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

Accepted Answer

They hold the two polynucleotide strands together by connecting complementary bases.

Question 19

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

Accepted Answer

Guanine forms three hydrogen bonds with cytosine.

Question 20

A scientist isolates a nucleic acid and finds it contains the base uracil. Which type of nucleic acid is it most likely to be?

Accepted Answer

RNA

Biological Molecules: The Carbon Compounds of Life (Chapter 3) – Nucleic Acids

Study Guide - Practice Questions