The answers lysosomes, they digest enzymes that break down waste material and the priests in the cell.
Genetic variation is a prerequisite for evolution because natural selection relies upon lessening the frequency of alleles in a population therefore there must be variance in the gene pool
Plant life, especially the trees in the Rain forest absorb the carbon dioxide and produce oxygen so without them, there would be much more carbon dioxide.
In fact we believe that the oxygen in our atmosphere has origin in plant life! Specifically ocean plants. <span />
