Question 1

Which experiment provided the first evidence that DNA, and not protein, is the genetic material, and what was the key finding?

Accepted Answer

Hershey and Chase's experiment; they demonstrated that only DNA from bacteriophages entered bacterial cells and directed viral replication.

Question 2

Which of the following best describes Chargaff’s rules?

Accepted Answer

The percentage of adenine equals thymine, and the percentage of guanine equals cytosine in DNA.

Question 3

Rosalind Franklin’s X-ray diffraction images were critical in determining which aspect of DNA structure?

Accepted Answer

The double helical structure and uniform diameter of DNA.

Question 4

Which enzyme is responsible for synthesizing short RNA primers during DNA replication?

Accepted Answer

Primase

Question 5

During DNA replication, which enzyme joins Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 6

Which of the following statements 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

A mutation occurs during DNA replication. Which enzyme is most directly responsible for correcting this error through proofreading?

Accepted Answer

DNA polymerase III

Question 8

Which of the following best explains why eukaryotic chromosomes have multiple origins of replication, while bacterial chromosomes typically have only one?

Accepted Answer

Eukaryotic chromosomes are linear and much larger, requiring multiple origins to replicate efficiently.

Question 9

Which of the following is a function of telomeres in eukaryotic chromosomes?

Accepted Answer

They protect chromosome ends from deterioration and prevent fusion with other chromosomes.

Question 10

A patient is exposed to UV radiation, which causes thymine dimers in their DNA. Which DNA repair mechanism is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair

Question 11

Which of the following best describes the difference between heterochromatin and euchromatin?

Accepted Answer

Heterochromatin is highly condensed and transcriptionally inactive; euchromatin is less condensed and transcriptionally active.

Question 12

Which of the following best describes antiparallel elongation during DNA replication?

Accepted Answer

One strand is synthesized continuously in the 5' to 3' direction, while the other is synthesized discontinuously in short fragments.

Question 13

Which of the following is NOT a difference between bacterial and eukaryotic chromosomes?

Accepted Answer

Bacterial chromosomes have multiple origins of replication; eukaryotic chromosomes have only one.

Question 14

Which enzyme relieves the strain caused by unwinding of the DNA double helix during replication?

Accepted Answer

Topoisomerase

Question 15

A scientist observes that after DNA replication, each daughter molecule contains one old strand and one new strand. Which model of replication does this observation support?

Accepted Answer

Semiconservative model

Question 16

Which of the following best describes Okazaki fragments?

Accepted Answer

Short DNA fragments synthesized on the lagging strand during DNA replication.

Question 17

Which of the following is a direct cause of DNA damage?

Accepted Answer

Exposure to ionizing radiation

Question 18

Which enzyme removes RNA primers and replaces them with DNA nucleotides during DNA replication in prokaryotes?

Accepted Answer

DNA polymerase I

Question 19

Which of the following statements about chromatin and chromosomes is correct?

Accepted Answer

Chromatin is the uncondensed form of DNA present during interphase; chromosomes are the condensed form visible during cell division.

Question 20

A mutation in the gene encoding DNA ligase would most directly affect which process during DNA replication?

Accepted Answer

Joining of Okazaki fragments on the lagging strand

Molecular Basis of Inheritance: Key Concepts and Study Guidance

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