Question 1

Which of the following best describes the structure of a DNA nucleotide?

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base

Question 2

Which of the following statements about Chargaff’s rules is correct?

Accepted Answer

The ratio of adenine to thymine is 1:1, and the ratio of guanine to cytosine is 1:1 in DNA

Question 3

Which of the following bases are classified as purines?

Accepted Answer

Adenine and guanine

Question 4

What was the key contribution of Rosalind Franklin to the discovery of DNA structure?

Accepted Answer

She produced X-ray diffraction images that revealed the helical structure of DNA

Question 5

Which of the following best explains why the sugar-phosphate backbone of DNA is on the outside of the double helix?

Accepted Answer

The sugar-phosphate backbone is hydrophilic and interacts with the aqueous environment

Question 6

If a DNA sample contains 30% adenine, what percentage of guanine would you expect to find according to Chargaff’s rules?

Accepted Answer

$$20\%$$

Question 7

Which of the following statements about DNA replication is correct?

Accepted Answer

Each new DNA molecule consists of one parental strand and one new strand

Question 8

During DNA replication, which enzyme is responsible for unwinding the double helix?

Accepted Answer

Helicase

Question 9

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments called Okazaki fragments

Question 10

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

Accepted Answer

Amino acid

Question 11

What is the main function of DNA polymerase during DNA replication?

Accepted Answer

To add nucleotides to the growing DNA strand

Question 12

Which of the following best explains why DNA synthesis requires energy?

Accepted Answer

Energy is required to form phosphodiester bonds between nucleotides

Question 13

Which enzyme solves the end-replication problem in eukaryotic chromosomes?

Accepted Answer

Telomerase

Question 14

A scientist is using PCR to amplify a segment of DNA. Which of the following components is NOT required for the reaction?

Accepted Answer

Ribosomes

Question 15

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

Accepted Answer

Adenine pairs with thymine, cytosine pairs with guanine

Question 16

Which of the following is a correct statement about the orientation of the two DNA strands in the double helix?

Accepted Answer

The two strands run in opposite directions (antiparallel)

Question 17

Which of the following best explains why purines always pair with pyrimidines in DNA?

Accepted Answer

To ensure the DNA helix is of uniform width

Question 18

A mutation causes a DNA strand to have 35% cytosine. According to Chargaff’s rules, what percentage of thymine would you expect?

Accepted Answer

$$15\%$$

Question 19

Which of the following best describes the role of Okazaki fragments during DNA replication?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand

Question 20

Which of the following real-world applications relies on the principles of DNA replication?

Accepted Answer

Polymerase chain reaction (PCR) for forensic DNA analysis

DNA Structure and Replication: From Genes to Proteins

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