[Alamo-Girl]

Viruses do mutate and are themselves amenable to evolutionary descriptions.

I was not implying that viruses are not living. To the contrary, I would characterize them as alive by reason of their information.

Non-living matter can have biological effects.

But non-living matter is not alive.

So being presented with one cell which is dead and one which is alive, how would you describe the difference?

[Doctor Stochastic]

So being presented with one cell which is dead and one which is alive, how would you describe the difference?

One is dead. The other is alive. But that isn't the interesting case (although it may be rather difficult to tell whether a cell is dead or alive.)

Living creatures can have dead cells (hair, nails, skin) and dead creatures can have living cells (all cells do not die at the same time when a mammal dies; some may even be kept "alive" indefinitely in a nutrient broth.)

The requirement of restricted environment shouldn't disqualify something from being called living.

[js1138]

So being presented with one cell which is dead and one which is alive, how would you describe the difference?

I have asked that question on these threads a number of times. What would you say about a snipet of DNA that is excised from one cell and inserted into a viable, reproducing line of creatures, possibly of another order?