Genetic variation<span> occurs </span>mainly<span> through DNA mutation, gene flow (movement of genes from one population to another) and sexual reproduction</span>
Population is the answer !
We all have the same genetic makeup. DNA
The specialization of cell in its broad sense,growth also include the phase of cell development
This one would be amplitude. The reason is because amplitude is the distance from the center of the wave to the farthest point on the wave. So, if the amplitude of a wave is, say, 5m, the distance between the center of the wave and the top (or bottom) would be 5 meters. And to find the total height, just double the amplitude.