The difference between bacteria and viruses that show bacteria are living and not viruses is that viruses, unlike bacteria, lack what is considered a living organism. For Example, viruses cannot reproduce without the help of a host, and don't use the normal way of cell-division for replication. Unlike bacteria, which can reproduce without the aid of a host.
So basically viruses don't have what it need to be a living organism, like reproducing without and host and aren't in the norm for cell-division for replication.
1. an atom
2. compound
3. both
4. atom
Seafloor spreading occurs at divergent plate boundaries. As tectonic plates slowly move away from each other, heat from the mantle's convection currents makes the crust more plastic and less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor.
A dichotomous key is two paired sentences that have contrasting characteristics. That's all i know