AP BIOLOGY

Detailed explanation-1: -The experiment done by Meselson and Stahl demonstrated that DNA replicated semi-conservatively, meaning that each strand in a DNA molecule serves as a template for synthesis of a new, complementary strand.

Detailed explanation-2: -Meselson & Stahl reasoned that these experiments showed that DNA replication was semi-conservative: the DNA strands separate and each makes a copy of itself, so that each daughter molecule comprises one “old” and one “new” strand.

Detailed explanation-3: -The semiconservative nature of replication of DNA was proved by Mathew Meselson and Franklin Stahl in 1985. They performed their experiment in the bacterium Escherichia coli. So, the correct answer is option D.

Detailed explanation-4: -Meselson and Stahl Experiment was an experimental proof for semiconservative DNA replication. In 1958, Matthew Meselson and Franklin Stahl conducted an experiment on E. coli which divides in 20 minutes, to study the replication of DNA.

Detailed explanation-5: -It was found that the daughter cells produced bands of DNA which was located at intermediate position between N14 and N15 which lead to the conclusion that the resultant daughter DNA contained two strands, one of N14 and the other is of N15, which act as an evidence for the semi-conservative nature of DNA replication.