Question 1

Which experiment provided the strongest evidence that DNA, and not protein, is the genetic material in cells?

Accepted Answer

Hershey and Chase’s bacteriophage labeling experiment using $$^{32}P$$ and $$^{35}S$$

Question 2

In the Hershey-Chase experiment, why was $$^{32}P$$ used to label DNA and $$^{35}S$$ used to label protein?

Accepted Answer

$$^{32}P is $$found in DNA but not in protein, and $$^{35}S is $$found in protein but not in DNA

Question 3

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 4

According to Chargaff’s rules, if a DNA sample contains 30% adenine, what percentage of guanine does it contain?

Accepted Answer

20%

Question 5

Which feature of DNA structure did Rosalind Franklin’s X-ray diffraction photograph reveal?

Accepted Answer

The helical shape and regular spacing of bases

Question 6

What is the significance of the antiparallel arrangement of DNA strands?

Accepted Answer

It enables complementary base pairing and proper replication

Question 7

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

Accepted Answer

Helicase

Question 8

Why is DNA replication described as 'semi-conservative'?

Accepted Answer

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

Question 9

Which enzyme joins Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

Ligase

Question 10

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

Accepted Answer

DNA polymerase

Question 11

What is the role of telomeres in eukaryotic chromosomes?

Accepted Answer

They postpone the erosion of genes near the ends of DNA molecules

Question 12

Which of the following best explains why prokaryotes do not face the same end-replication problem as eukaryotes?

Accepted Answer

Prokaryotes have circular chromosomes

Question 13

Which of the following is a direct consequence of mutations that escape DNA repair mechanisms?

Accepted Answer

Permanent changes in the DNA sequence that can be inherited

Question 14

Which of the following statements about chromatin is correct?

Accepted Answer

Euchromatin is loosely packed and accessible for gene expression

Question 15

A scientist isolates a DNA molecule and finds that 35% of its bases are cytosine. According to Chargaff’s rules, what percentage of the bases are adenine?

Accepted Answer

15%

Question 16

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

Accepted Answer

Primase

Question 17

What is the evolutionary significance of mutations that occur during DNA replication?

Accepted Answer

They are the source of genetic variation for natural selection

Question 18

Which of the following best describes the function of histones in eukaryotic cells?

Accepted Answer

They package and organize DNA into nucleosomes

Question 19

A patient is exposed to X-rays, which cause DNA damage. Which DNA repair mechanism is most likely to remove and replace the damaged DNA segment?

Accepted Answer

Nucleotide excision repair

Question 20

Which of the following statements about the directionality of DNA synthesis is correct?

Accepted Answer

DNA synthesis occurs in the 5' to 3' direction

The Molecular Basis of Inheritance: Structure and Replication of DNA

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