Answer:
DNA replication is considered a semi-conservative process because each new DNA molecule formed after replication consists of one strand that is newly synthesized (newly formed) and one strand that is conserved (original).
When DNA replication occurs, the DNA molecule unwinds, and each original strand serves as a template for the synthesis of a new complementary strand. This process results in two identical DNA molecules, each containing one original (conserved) strand and one newly synthesized strand.
The term "semi-conservative" reflects this partial conservation of the original genetic material in each new DNA molecule. It was first proposed by James Watson and Francis Crick in 1953 and was later confirmed by experiments conducted by Matthew Meselson and Franklin Stahl in 1958.
In summary, DNA replication is considered semi-conservative because it involves the synthesis of new DNA strands complementary to the original strands, resulting in two daughter molecules, each with one conserved strand and one newly synthesized strand.