Question 1

Which experiment provided the first strong evidence that DNA is the genetic material, rather than protein?

Accepted Answer

Avery, MacLeod, and McCarty's experiment showing DNA transforms bacteria

Question 2

Which of the following best describes the structure of DNA as proposed by Watson and Crick?

Accepted Answer

A double helix with antiparallel strands and complementary base pairing

Question 3

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to the 3' end?

Accepted Answer

DNA polymerase

Question 4

What is the function of the origin of replication in DNA replication?

Accepted Answer

It is the site where DNA replication begins, allowing the DNA to unwind and form replication forks.

Question 5

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

Accepted Answer

The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously as Okazaki fragments.

Question 6

A mutation occurs in a gene that codes for DNA ligase. What is the most likely consequence during DNA replication?

Accepted Answer

Okazaki fragments on the lagging strand will not be joined together, resulting in incomplete DNA molecules.

Question 7

Which enzyme is responsible for unwinding the DNA double helix at the replication fork?

Accepted Answer

DNA helicase

Question 8

If a cell's proofreading and repair mechanisms fail, what is the most likely outcome?

Accepted Answer

Permanent mutations may accumulate in the DNA, potentially leading to altered gene products.

Question 9

Which of the following equations correctly represents the complementary base pairing in DNA?

Accepted Answer

$$A = T, \ C = G$$

Question 10

A scientist discovers a new organism whose DNA contains 30% adenine. According to Chargaff's rules, what percentage of guanine would you expect to find?

Accepted Answer

20%

Question 11

Which of the following best describes the role of primase during DNA replication?

Accepted Answer

It synthesizes short RNA primers to provide a starting point for DNA polymerase.

Question 12

A patient is diagnosed with a genetic disorder caused by a point mutation in a DNA repair gene. Which process is most likely affected?

Accepted Answer

The correction of mismatched bases during DNA replication

Question 13

Which of the following statements about mutations is correct?

Accepted Answer

Mutations are permanent changes in the nucleotide sequence of DNA and can be heritable.

Question 14

During DNA replication, which direction does DNA polymerase synthesize the new strand?

Accepted Answer

$$5' \rightarrow 3'$$

Question 15

Which process is responsible for correcting errors that occur during DNA replication?

Accepted Answer

Proofreading by DNA polymerase and DNA repair enzymes

Question 16

A researcher exposes bacterial cells to UV radiation, causing thymine dimers in the DNA. Which repair mechanism is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair

Question 17

Which of the following is NOT a function of DNA polymerase during replication?

Accepted Answer

Joining Okazaki fragments

Question 18

In a cell, what would happen if the replication fork stalled and could not proceed?

Accepted Answer

DNA synthesis would halt, potentially leading to incomplete or damaged chromosomes.

Question 19

Which of the following best describes the semi-conservative model of DNA replication?

Accepted Answer

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

Question 20

A mutation changes a cytosine to a thymine in a gene. What type of mutation is this?

Accepted Answer

Substitution

DNA: The Molecular Basis of Inheritance, Replication, and Repair

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