Question 1

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

Accepted Answer

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

Question 2

Which of the following statements about the structure of DNA is CORRECT according to the Watson and Crick model?

Accepted Answer

The two strands of DNA are antiparallel and form a right-handed double helix.

Question 3

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

Accepted Answer

Cytosine

Question 4

What type of bond links individual nucleotides together in a nucleic acid polymer?

Accepted Answer

Phosphodiester bond

Question 5

Which observation by Rosalind Franklin was critical in supporting the double helix model of DNA?

Accepted Answer

DNA is a helical molecule with bases stacked 3.4 Å apart.

Question 6

A DNA molecule is found to have 30% adenine. According to Chargaff's rule, what percentage of guanine would you expect?

Accepted Answer

$$20\%$$

Question 7

Which of the following best explains why nucleic acids are considered polyanions at physiological pH?

Accepted Answer

The sugar-phosphate backbone contains acidic phosphate groups that are deprotonated.

Question 8

Which of the following is TRUE regarding the directionality of nucleic acid synthesis?

Accepted Answer

Nucleic acids are synthesized from the 5' to 3' direction.

Question 9

Which of the following statements about RNA is CORRECT?

Accepted Answer

RNA contains uracil instead of thymine.

Question 10

A mutation replaces a cytosine with a thymine in a DNA strand. Which of the following base-pairing changes would occur as a result?

Accepted Answer

A guanine would pair with thymine instead of cytosine.

Question 11

Which of the following best describes the condensation reaction that forms the phosphodiester bond in nucleic acids?

Accepted Answer

A water molecule is removed to join the 3' hydroxyl of one nucleotide to the 5' phosphate of another.

Question 12

Which of the following is a real-world application of DNA manipulation?

Accepted Answer

Using DNA sequencing to diagnose genetic diseases.

Question 13

Which of the following is a feature of the major and minor grooves in the DNA double helix?

Accepted Answer

They are formed by the sugar-phosphate backbone and provide binding sites for proteins.

Question 14

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

Accepted Answer

DNA lacks a 2' hydroxyl group, making it less susceptible to hydrolysis.

Question 15

A scientist isolates a nucleic acid with the following composition: contains uracil, ribose sugar, and forms stem-loop structures. What is the most likely identity of this molecule?

Accepted Answer

Single-stranded RNA

Question 16

Which of the following is a correct pairing of nitrogenous bases in DNA?

Accepted Answer

Adenine pairs with thymine

Question 17

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

Accepted Answer

Histones are small, positively charged proteins that help condense and organize DNA within the cell nucleus.

Question 18

Which of the following statements about chromosomes is CORRECT?

Accepted Answer

Each chromosome contains a single, very long molecule of DNA that is tightly coiled and packaged with proteins.

Question 19

Which of the following is a consequence of the antiparallel nature of DNA strands?

Accepted Answer

One strand runs 5' to 3', while the other runs 3' to 5'.

Nucleotides, Nucleic Acids, and Genetic Information: Structure and Function

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