Question 1

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

Accepted Answer

Ability to catalyze metabolic reactions

Question 2

In Griffith's transformation experiment, which combination of bacterial strains resulted in the death of mice, demonstrating the 'transforming principle'?

Accepted Answer

Live R strain and heat-killed S strain

Question 3

What was the main conclusion of the Hershey-Chase experiment using T2 bacteriophage?

Accepted Answer

DNA, not protein, is the genetic material

Question 4

Which isotope was used to label DNA in the Hershey-Chase experiment?

Accepted Answer

$$^{32}\mathrm{P}$$

Question 5

Avery, MacLeod, and McCarty demonstrated that the transforming principle was DNA by showing that transformation did NOT occur when the extract was treated with which enzyme?

Accepted Answer

DNase

Question 6

Which of the following best describes the structure of DNA as proposed by Watson and Crick?

Accepted Answer

A double helix with antiparallel strands

Question 7

Which base pairs with cytosine in DNA?

Accepted Answer

Guanine

Question 8

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

Accepted Answer

30%

Question 9

Which experiment first suggested that a 'transforming principle' could transfer genetic information between bacteria?

Accepted Answer

Griffith's experiment

Question 10

Which of the following statements about the S (smooth) and R (rough) strains of Streptococcus pneumoniae is correct?

Accepted Answer

The S strain is virulent due to its polysaccharide capsule

Question 11

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

Accepted Answer

Proteins are more chemically diverse and abundant than DNA

Question 12

A scientist treats a mixture of DNA and RNA with RNase, then adds the mixture to R strain bacteria. What is the expected result?

Accepted Answer

S transformants are produced

Question 13

Which of the following is a direct result of the ability of DNA to replicate accurately?

Accepted Answer

Genetic information is reliably passed from one generation to the next

Question 14

In the Hershey-Chase experiment, what was the significance of finding $$^{32}\mathrm{P} in $$the bacterial pellet after centrifugation?

Accepted Answer

It demonstrated that DNA entered the bacteria and directed viral replication

Question 15

Which of the following best describes the role of X-ray crystallography in the discovery of DNA structure?

Accepted Answer

It provided evidence for the helical structure of DNA

Question 16

Which of the following is a correct pairing of a DNA component and its function?

Accepted Answer

Phosphate group: forms the backbone of DNA

Question 17

A mutation prevents the formation of the polysaccharide capsule in Streptococcus pneumoniae. What is the most likely effect on the bacterium's virulence?

Accepted Answer

The bacterium becomes nonvirulent

Question 18

Which of the following experiments directly disproved the hypothesis that proteins are the genetic material?

Accepted Answer

Hershey-Chase experiment

Question 19

Which of the following best explains why $$^{35}\mathrm{S}$$ was used to label protein in the Hershey-Chase experiment?

Accepted Answer

Sulfur is present in proteins but not in DNA

Question 20

Which of the following is a real-world application of understanding that DNA is the genetic material?

Accepted Answer

Forensic identification using DNA fingerprinting

The Chemical and Physical Structure of the Genetic Material: Key Experiments and Concepts

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