What is the first division of animals based upon? A) if they have backbones or not
B) if they have brains or not
C) if they walk or fly
D) if they have feathers or fur

Answer is explained below.

Explanation:

The DNA (deooyrtonucleic acid) molecule undergoes replication in conservative manner

The two strands separate, a new strand is synthesized by the incorporation of nucleotides   followed by ligation.

Thus, in the daughter double helix,  one of the strand is newly synthesized So. whet replication  occurs in vitro ,  with the help of radioactive phosphate, me newly synthesized strand can be traced  .A detailed diagram of the DNA replication in a medium contain radioactive phosphate is shown  in attached image.

The blue dotted ones are the sequence of nucleotides incorporated. The parent template with

non-radioactive phosphate (solid line) is copied in the daughter cells. This is consistent with the

Messelsion and Stahl experiments. In the next cycle, the hybrid strands separate and act as

template, in which a hybrid strands and a non-hybrid strands with radiophosphates on either

strands is formed.

With the cycles of replication, the strand with radioactive isotopes increase compared to the

mother strand with non-radioactive phosphates.