Question 1

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

Accepted Answer

A nucleotide consists of a phosphate group attached to the 5' carbon of deoxyribose, a nitrogenous base attached to the 1' carbon, and a deoxyribose sugar.

Question 2

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

Accepted Answer

Helicase

Question 3

Which of the following best explains why DNA strands are described as 'antiparallel'?

Accepted Answer

The two strands have complementary base sequences and run in opposite 5' to 3' directions.

Question 4

A scientist analyzes a DNA sample and finds that 30% of the bases are adenine. According to Chargaff’s rule, what percentage of the bases are cytosine?

Accepted Answer

$$20\%$$

Question 5

Which of the following is a structural difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar.

Question 6

Which of the following best describes the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand by forming phosphodiester bonds.

Question 7

In the Hershey and Chase experiment, what evidence demonstrated that DNA, and not protein, is the genetic material?

Accepted Answer

Radioactive phosphorus was found inside the bacterial cells, indicating DNA entered the cells.

Question 8

Which of the following statements about the leading and lagging strands during DNA replication is correct?

Accepted Answer

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

Question 9

A mutation occurs during DNA replication. Which mechanism is primarily responsible for correcting mismatched bases immediately after they are incorporated?

Accepted Answer

Proofreading by DNA polymerase

Question 10

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each new DNA molecule consists of one parental strand and one newly synthesized strand.

Question 11

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

Accepted Answer

Adenine

Question 12

What is the role of topoisomerase during DNA replication?

Accepted Answer

It relieves the tension ahead of the replication fork by cutting and rejoining DNA strands.

Question 13

Which of the following best explains why telomeres are important in eukaryotic DNA replication?

Accepted Answer

They prevent the loss of essential genes during DNA replication by providing a buffer region at chromosome ends.

Question 14

Which of the following statements about chromatin structure is correct?

Accepted Answer

Euchromatin is less condensed and is the region where DNA replication and transcription occur.

Question 15

Which of the following best describes the direction in which DNA polymerase synthesizes new DNA?

Accepted Answer

DNA polymerase synthesizes DNA in the 5' to 3' direction.

Question 16

A researcher is studying a eukaryotic cell in metaphase. Which of the following best describes the organization of its DNA at this stage?

Accepted Answer

DNA is highly condensed into metaphase chromosomes, with multiple levels of coiling and histone association.

Question 17

Which of the following is true regarding the difference between bacterial and eukaryotic DNA replication?

Accepted Answer

Eukaryotic DNA replication begins at multiple origins of replication, while bacterial DNA replication typically begins at a single origin.

Question 18

Which of the following best describes the process of nucleotide excision repair?

Accepted Answer

Damaged DNA is recognized, a segment containing the damage is removed, and the gap is filled by DNA polymerase and sealed by ligase.

Question 19

Which of the following statements about ATP is correct?

Accepted Answer

ATP is a nucleotide because it contains a nitrogenous base, a sugar, and three phosphate groups.

Question 20

A DNA strand has the following sequence: 5'-ATCGGTA-3'. What is the sequence of the complementary strand, and in which direction should it be written?

Accepted Answer

3'-TAGCCAT-5'

Chapter 13: The Molecular Basis of Inheritance – DNA Structure, Replication, and Chromatin Organization

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