What is Life?

Sure I've mentioned this before but back to reexamine obvious points about life...

We take a cell from the body of multicellular organism and keep it in a petri-dish. Is this cell alive?

It seems to be accepted that "Life" involves the following 7 things: respire, feed, excrete, grow, move, sensitivity, reproduce.

Well unless it is an extremely specialised cell then it probably still has the capability to do these 7 things.

But if each cell is "alive" then is the organism living that is made from them? i.e. a repeating point in this blog: is the organism anything other than the cells that comprise it?

The note I made to myself when a student inspired this was: is life within the cells or between the cells?

They do not classify viruses as living because they don't fulfill the characteristics: that is viruses taken separate from the machinary of a cell. But in association with a cell they become involved with these essential characteristics albeit temporarily. So what of commensal organisms that co-exist like lichens or interdependent organisms like predator and prey or parasitoids? By themselves they perform the characteristics only in so far as they have items upon which to feed. A propensity to feed is nothing without food. So to fulfill feeding organisms depend upon environment and community. Can a "living thing" be isolated on the petri dish and the "Life" studied as somehow being "contained" within its cell walls or epithelium. Can any of these characteristics arise within the membrane? Or is it between the membrane and the environment that it occurs?

This is a perennial problem in thought being applied to "Life".