Question 1

Which experiment first demonstrated that a 'transforming principle' could transfer genetic information from dead, virulent bacteria to live, non-virulent bacteria, resulting in the death of mice?

Accepted Answer

Griffith experiment (1928)

Question 2

In the Hershey-Chase experiment, which radioactive label was found inside the bacteria, demonstrating that DNA is the genetic material?

Accepted Answer

$^{32}P$ (phosphorus)

Question 3

Which of the following best describes the chemical composition of a DNA nucleotide?

Accepted Answer

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

Question 4

According to Chargaff's rules, which of the following equations is always true for double-stranded DNA?

Accepted Answer

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

Question 5

Which scientist(s) used X-ray diffraction to determine that DNA was helical in structure?

Accepted Answer

Franklin and Wilkins

Question 6

What is the significance of the antiparallel arrangement of the two DNA strands in the double helix?

Accepted Answer

It allows complementary base pairing and proper hydrogen bond formation

Question 7

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

Accepted Answer

Adenine pairs with thymine via two hydrogen bonds; guanine pairs with cytosine via three hydrogen bonds

Question 8

A scientist isolates a nucleic acid from the nucleus of a cell and finds it contains high amounts of nitrogen and phosphorus, is acidic, and is associated with the nucleus. Who made similar observations and named the molecule 'nucleic acid'?

Accepted Answer

Miescher

Question 9

Which of the following best explains why the Hershey-Chase experiment was a critical step in identifying DNA as the genetic material?

Accepted Answer

It demonstrated that DNA, not protein, was transferred into bacteria by phages

Question 10

Which of the following is a pyrimidine found in DNA?

Accepted Answer

Thymine

Question 11

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

Accepted Answer

20%

Question 12

Which of the following best describes the backbone of a DNA molecule?

Accepted Answer

Alternating deoxyribose and phosphate groups

Question 13

A mutation changes a cytosine in DNA to a thymine. Which type of hydrogen bonding will be disrupted?

Accepted Answer

Three hydrogen bonds between guanine and cytosine

Question 14

Which of the following statements about the addition of new nucleotides during DNA synthesis is correct?

Accepted Answer

New nucleotides are added to the 3' end of the growing DNA strand

Question 15

Which of the following best explains why the sum of hydrogen bonds in a DNA molecule makes it stable, even though each individual hydrogen bond is weak?

Accepted Answer

The large number of hydrogen bonds collectively provides significant stability

Question 16

Which of the following is NOT a component of a DNA nucleotide?

Accepted Answer

Fatty acid

Question 17

Watson and Crick's DNA model explained Chargaff's rules by showing that:

Accepted Answer

Each purine pairs with a pyrimidine via hydrogen bonds

Question 18

Which of the following best describes the orientation of the two DNA strands in the double helix?

Accepted Answer

The strands run antiparallel: one 5' to 3', the other 3' to 5'

Question 19

Which of the following historical experiments provided evidence that DNA, and not protein, was the hereditary material by using enzymes to degrade specific macromolecules?

Accepted Answer

Avery, MacLeod, and McCarty's experiment

Question 20

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

Accepted Answer

Adenine

DNA Structure and Packaging: Key Experiments and Molecular Details

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