Question 1

Which experiment provided the first strong evidence that DNA is the genetic material responsible for heredity?

Accepted Answer

Avery, McLeod, and McCarty's experiment using purified DNA from bacteria

Question 2

In Hershey and Chase's experiment, which radioactive isotope was used to label DNA, and what was the key finding?

Accepted Answer

Phosphorus-32 ($^{32}P$); DNA entered the bacterial cell, proving it was the genetic material

Question 3

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 4

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to a template strand?

Accepted Answer

DNA polymerase

Question 5

If a DNA molecule has 20% adenine, what percentage of guanine would you expect according to Chargaff's rules?

Accepted Answer

$30\%$

Question 6

Which statement about the semiconservative model of DNA replication is correct?

Accepted Answer

Each daughter DNA molecule consists of one parental strand and one newly synthesized strand

Question 7

What is the function of DNA ligase during DNA replication?

Accepted Answer

Joins Okazaki fragments on the lagging strand

Question 8

Which of the following best explains why telomeres are important for chromosome stability?

Accepted Answer

They prevent the loss of coding DNA during replication

Question 9

A mutation in the gene encoding DNA polymerase proofreading activity would most likely result in:

Accepted Answer

Higher frequency of mutations during DNA replication

Question 10

Which process is responsible for the separation of parental DNA strands during replication?

Accepted Answer

Helicase activity

Question 11

In the Meselson-Stahl experiment, what was the key evidence supporting the semiconservative model of DNA replication?

Accepted Answer

After one round of replication, DNA had intermediate density between heavy and light

Question 12

Which of the following is a real-world consequence of defective DNA repair mechanisms?

Accepted Answer

Increased risk of cancer due to accumulation of mutations

Question 13

Which base pairs with cytosine in DNA, and how many hydrogen bonds are formed between them?

Accepted Answer

Guanine; three hydrogen bonds

Question 14

During DNA replication, which strand is synthesized discontinuously and what are the resulting fragments called?

Accepted Answer

Lagging strand; Okazaki fragments

Question 15

Which enzyme synthesizes short RNA primers needed for DNA polymerase to begin synthesis?

Accepted Answer

Primase

Question 16

A patient is diagnosed with xeroderma pigmentosum, a disorder caused by defective repair of UV-induced DNA damage. Which repair mechanism is most likely affected?

Accepted Answer

Nucleotide excision repair

Question 17

Which of the following statements about telomerase is correct?

Accepted Answer

Telomerase extends the ends of chromosomes by adding repetitive DNA sequences

Question 18

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

Accepted Answer

Joining Okazaki fragments

Question 19

A scientist is studying a bacteriophage that injects only its DNA into a bacterial cell. What does this suggest about the genetic material of the phage?

Accepted Answer

DNA is the genetic material responsible for viral replication

Question 20

Which of the following best explains why DNA replication is considered 'semi-discontinuous'?

Accepted Answer

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

DNA as the Genetic Material and Mechanisms of DNA Replication

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