The man responsible for developing the modern scientific classification system, that scientists still use and follow today is Carolus Linnaeus.
It mutates because you are immune, but yes it mutates and gets a new trait to trick your body into letting it in.
A control group is kept the same to determine whether or not what you did for an experiment on the experimental group was actually caused by the experiment performed, and not other environmental changes. By keeping the same climate, environments, nourishment, etc. on a control group and experimental group, but only performing the experiment on the experimental group, you can prove your experiment actually works.
The smallest level of organizations in livings are cells.
