Question 1

Which of the following experiments provided the first direct experimental proof that DNA is the biomolecule responsible for heredity?

Accepted Answer

Avery, MacLeod, and McCarty's experiment using enzymatic digestion

Question 2

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

Accepted Answer

DNA contains phosphorus but not sulfur, and protein contains sulfur but not phosphorus

Question 3

If a DNA sample from an organism contains 15% thymine, what percentage of the sample should be cytosine?

Accepted Answer

35%

Question 4

Which property of DNA allows it to serve as a template for its own replication?

Accepted Answer

Complementarity of the two strands due to specific base pairing

Question 5

Which of the following best describes the antiparallel nature of DNA?

Accepted Answer

The two strands run in opposite 5' to 3' directions

Question 6

A scientist treats heat-killed virulent bacteria with RNase and DNase, then mixes with live avirulent bacteria. Transformation occurs. What conclusion can be drawn?

Accepted Answer

Protein is not the genetic material

Question 7

Which of the following is NOT a requirement for a molecule to serve as genetic material?

Accepted Answer

Ability to catalyze metabolic reactions

Question 8

Which alternative form of DNA is left-handed and found in synthetic DNA oligonucleotides containing only G-C pairs?

Accepted Answer

Z-DNA

Question 9

What is the significance of Chargaff's rules in understanding DNA structure?

Accepted Answer

They demonstrated that the amount of purines equals the amount of pyrimidines

Question 10

Which of the following bonds links adjacent nucleotides in a single strand of DNA?

Accepted Answer

Phosphodiester bonds

Question 11

A mutation causes a mismatch in base pairing, such as A-G. What is the most likely consequence for the DNA double helix?

Accepted Answer

The diameter of the helix will be distorted

Question 12

Which of the following best explains why proteins were initially favored as the genetic material over DNA?

Accepted Answer

Proteins have greater chemical diversity due to 20 amino acids

Question 13

Which of the following is a correct statement about the structure of B-DNA?

Accepted Answer

It is a right-handed helix with 10 base pairs per turn

Question 14

Which of the following best describes the role of hydrogen bonds in the DNA double helix?

Accepted Answer

They provide specificity and stability by connecting complementary bases on opposite strands

Question 15

A DNA molecule is subjected to X-ray diffraction. What information can be obtained from the resulting pattern?

Accepted Answer

The helical nature and regularities of the molecule

Question 16

Which of the following is a function of nucleoside triphosphates (such as ATP and GTP) in the cell?

Accepted Answer

They are precursors for nucleic acid synthesis and play a role in cell bioenergetics

Question 17

Which of the following statements about the central dogma of molecular genetics is correct?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein

Question 18

Which of the following would NOT be a likely outcome if Griffith had mixed heat-killed IIIS bacteria and heat-killed IIR bacteria and injected them into a mouse?

Accepted Answer

The mouse would contract pneumonia and die

Question 19

Why can't the Hershey-Chase experiment distinguish between DNA and RNA as the genetic material?

Accepted Answer

Both DNA and RNA contain phosphorus but not sulfur

Question 20

Which of the following is a real-world application of understanding the chemical structure of DNA?

Accepted Answer

Developing forensic DNA fingerprinting techniques

DNA Structure and the Evidence for DNA as Genetic Material

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