Many kinds of prokaryotes and eukaryotes contain a structure outside the cell membrane called the cell wall. With only a few exceptions, all prokaryotes have thick, rigid cell walls that give them their shape. Among the eukaryotes, some protists, and all fungi and plants, have cell walls.
About 8.7 Million Species
A singularity did.
A singularity is an infinitely small and infinitely dense point of matter from which the universe came. The big bang theory suggests that the big bang was like a balloon inflating from that infinitely tiny point into the universe we know today. There is plenty of evidence about this.
<span>What MUST occur before mitosis and meiosis can occur is B) DNA replication. DNA replication is a process of copying DNA into an identical copy. Before mitosis, the genetic material of the mother cell must duplicate so that each daughter cell have the same amount as the mother cell. On the other hand, meiosis is a reductive division. But meiosis II is similar to mitosis, so DNA replication is also necessary.</span>
