Question

question completion status: question 1 griffiths experiment with pneumococcus demonstrated that a. dna, not protein, is the genetic molecule. b. materials from dead organisms can affect and change living organisms. c. smooth bacteria can survive heating. d. none of the above question 2 chargaffs rule states that a. dna must be replicated before a cell can divide. b. only nucleic acids enter the cell during infection. c. viruses enter cells without their protein coat. d. the amount of purines equals the amount of pyrimidines. question 3 information sources used by watson and crick to determine the structure of dna included a. light micrographs of individual bacterial chromosomes. b. nuclear magnetic resonance analysis of dna. c. electron micrographs of individual dna molecules. d. x - ray crystallography of double - stranded dna.

Explanation:

• Question 1: Griffith's experiment showed that materials from dead (heat - killed smooth) organisms can transform living (rough) organisms. It was Avery - MacLeod - McCarty who later showed DNA was the genetic molecule, and smooth bacteria do not survive heating (they were heat - killed in the experiment).
• Question 2: Chargaff's rule is about base - pairing. In DNA, the amount of purines (adenine and guanine) equals the amount of pyrimidines (cytosine and thymine). DNA replication before cell division is related to the cell cycle, only nucleic acids entering the cell during infection is related to the Hershey - Chase experiment, and viruses entering cells without their protein coat is also related to the Hershey - Chase experiment.
• Question 3: Watson and Crick used Rosalind Franklin's X - ray crystallography data of double - stranded DNA. Light micrographs of bacterial chromosomes do not show the fine structure of DNA, nuclear magnetic resonance analysis was not a main source for them, and electron micrographs of individual DNA molecules were not used in their determination of the double - helix structure.

Answer:

• Question 1: B. materials from dead organisms can affect and change living organisms.
• Question 2: D. the amount of purines equals the amount of pyrimidines.
• Question 3: D. X - ray crystallography of double - stranded DNA.