I would say life is anything that can reproduce itself and move without an outside force being applied.
Therefore biology would be the studying of anything that fits under the criteria of life.
The time period between conception and death. It probably doesn’t do to place too many conditions on the whole experience, like self awareness, learning, growth, otherwise we discount chavs and they are at least in theory alive. Plus I don’t think there really is a definition that could not be condensed into a 67 volume set let alone a paragraph or two.
Nothing neither of them are really living.
Biologically respiration, in a real sense nothing, that’s why we tend to pull the switch.
I think life is the highest essence given us by some unknown forces - to live our lives, to build a community, to raise kids for continuing our klan. This is life and please don’t try getting deeper into it - you will simply complicate the things.
Truly I think it takes a neutral and unbiased observer to say what is alive and what isn’t.
A rock could claim its alive simply so it could pretend to be more important to others but no one would believe it.