Single-celled organisms do not undergo Apoptosis or necrosis. Is that clearer?
Well yes, js1138 — thank you for the clarification!
A couple thoughts. It seems to me that apoptosis and necrosis must be quantified by different information measures, since — while both lead to death — one is an "orderly" or "controlled" process, and the other a "random" process. The distinction between the two seems to be a purely "informational" one.
Another thing, "biological immortality" is, as you know, a technical term currently in favor in some circles of biology. It describes the situation where a sustained, cumulative increase in the rate of mortality as a function of chronological age is absent. Biological entities so characterized are said to be exempt from the Hayflick limit, which is essentially a description of the situation in which cells no longer divide.
But to extend "biological immortality" beyond the range of this narrow, technical understanding would be absurd.
For there is no logical sense whatever in claiming that a being incapable of death was ever actually alive in the first place. Or so it seems to me, FWIW.