NEET BIOLOGY

Detailed explanation-1: -Watson and Crick outlined a model for DNA replication, later called semi-conservative replication. According to Watson and Crick, in preparation for DNA replication, the two strands of DNA first unwound and separated.

Detailed explanation-2: -The semiconservative mode of DNA replication was originally documented through the classic density labeling experiments of Matthew Meselson and Franklin W. Stahl, as communicated to PNAS by Max Delbrück in May 1958.

Detailed explanation-3: -Watson and Crick observed that the two strands of DNA are anti-parallel and complementary to each other with respect to their base sequences. This type of arrangement in DNA molecule led to the hypothesis that DNA replication is semi-conservative.

Detailed explanation-4: -Answer: Watson and Crick defined DNA as a double helix with two long helical strands twisted together in their paper titled A Structure of Deoxyribose Nucleic Acid. According to them, each DNA strand has discrete units known as bases.