Question 1

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

Accepted Answer

Hershey-Chase experiment

Question 2

What is the chemical difference between the sugars found in DNA and RNA?

Accepted Answer

DNA contains deoxyribose, RNA contains ribose

Question 3

According to Chargaff's rules, which of the following equations correctly represents the relationship between base pairs in double-stranded DNA?

Accepted Answer

$$[A] = [T]$$ and $$[C] = [G]$$

Question 4

Which of the following best describes a nucleotide?

Accepted Answer

A pentose sugar, a nitrogenous base, and a phosphate group

Question 5

In the Hershey-Chase experiment, which isotope was used to label DNA?

Accepted Answer

$$^{32}P$$

Question 6

What type of bond connects the sugar and phosphate groups in the backbone of DNA?

Accepted Answer

Phosphodiester bond

Question 7

Which DNA conformation is most commonly found in living cells and is characterized by a right-handed double helix?

Accepted Answer

B-DNA

Question 8

If a DNA molecule has 30% adenine, what percentage of guanine would you expect according to Chargaff's rules?

Accepted Answer

20%

Question 9

Which scientist's work with X-ray crystallography was critical in revealing the helical structure of DNA?

Accepted Answer

Rosalind Franklin

Question 10

What is the melting temperature ($$T_m) of a $$DNA molecule with 40% G-C content, using the formula $$T_m = 2(A+T) + 4(G+C)$$?

Accepted Answer

Question 11

Which of the following statements about hydrogen bonding in DNA is correct?

Accepted Answer

Adenine forms two hydrogen bonds with thymine

Question 12

What is the main structural difference between B-DNA and Z-DNA?

Accepted Answer

B-DNA has a uniform major groove, Z-DNA has a zigzag backbone

Question 13

Which of the following best explains why single-stranded DNA (ssDNA) absorbs more ultraviolet light at 260 nm than double-stranded DNA (dsDNA)?

Accepted Answer

Base stacking in dsDNA reduces absorbance

Question 14

Which scientist demonstrated that the nucleus is the cellular agent of heredity using Acetabularia?

Accepted Answer

Joachim Hammerling

Question 15

A DNA sample is found to have 18% cytosine. What is the expected percentage of thymine?

Accepted Answer

32%

Question 16

Which of the following is NOT a feature of the B-form DNA double helix?

Accepted Answer

Left-handed helix

Question 17

Which of the following best describes the role of phosphodiester linkages in nucleic acids?

Accepted Answer

They connect adjacent nucleotides via the 3' and 5' carbons of the sugar

Question 18

Which of the following historical discoveries first suggested that chromosomes carry hereditary information?

Accepted Answer

Sturtevant's chromosome mapping

Question 19

Which of the following is a purine base found in DNA?

Accepted Answer

Adenine

Question 20

Which of the following statements about the directionality of nucleic acid strands is correct?

Accepted Answer

DNA strands are antiparallel, with one running 5' to 3' and the other 3' to 5'

DNA Structure, Function, and the Molecular Basis of Heredity

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