DNA replication is said to be semiconservative because it results in the synthesis of two new DNA molecules, each consisting of one original (“conservative”) strand and one newly synthesized (“semi”) strand.

During DNA replication, the two strands of the double helix unwind and separate, and each strand serves as a template for the synthesis of a new complementary strand. The result is the production of two DNA molecules, each containing one original strand and one newly synthesized strand.

This semiconservative mode of replication was first proposed by James Watson and Francis Crick, who were awarded the Nobel Prize in Physiology or Medicine in 1962 for their discovery of the structure of DNA. Their hypothesis was later confirmed through experiments conducted by Matthew Meselson and Franklin Stahl in the 1950s.

The semiconservative mode of replication is important because it ensures that each daughter cell receives a complete set of genetic instructions and is able to function properly. It also helps to maintain the accuracy of genetic information, as errors that occur during DNA replication can have a variety of effects on an organism.