For giving you understanding ; we need Free O2 but Oxygen is also available in H20 right why dont we use it !!
As the early atmosphere was reducing as there was no free oxygen but it was later produced by chemoautotrophic bacteria !! Living thing release O2 in atmosphere thus making it oxidising in nature and then life evolves !!
Plankton is part of an aquatic ecosystem
True ..In animals, the female mitotic sequence produces only one ovum; the other three haploid cells become "polar bodies".
It is an explosive cell that is used for protection from predators or prey hunting by the species of the phylum Cnidaria
Answer:
a large boulder I guess , please double check
