Synthesis of $DNA$ takes place by

In Meselson and Stahl's experiments,heavy $DNA$ was distinguished from normal $DNA$ by centrifugation in

$DNA$ polymerase is required for:

New $DNA$ synthesis occurs in the $P$ direction,and the $DNA$ polymerase enzyme reads the template in the $Q$ direction.
$\quad \quad \quad \quad P \quad \quad \quad \quad \quad Q$

Define the following terms:
$1.$ Template strand
$2.$ Semi-conservative replication

On which organism did Taylor perform experiments to prove the semi-conservative mode of chromosome replication?