In order to understand the totality of the interactions among the organisms in the biosphere, we need to at least understand <span>how the all genes function within organisms and </span>interact<span> with others organism and environment around it.
If we try to make this effort in a world where organisms will keep evolving and environment will keep changing like us, that tasks is impossible to finish.</span>
Globalized evolution...... but I might be wrong
Well yes, but a dichotomous key can be used to classify just about anything you want.
Hope that helped