Questions tagged with life should be about life in general, not about its mechanics. For example, a question about lifestyle on a particular planet would be a good use of this tag. A question about how a particular planet would affect the cells of a living organism would not fit this tag, the biology tag should be used instead.
I would suggest that, in order to alleviate confusion, this tag should be renamed lifestyle. Doing this would make the tagging system a whole lot more intuitive for people who ask
mechanics of life questions.