Alive is more than what the scientific definition says. It's so much more. A computer isn't flesh and blood, but it can still be alive. Some of them, anyway.

A plant could have a soul, if it had something that made it distinctly itself and not just another plant. You can't distinguish one blade of grass from another, not really, but beings with souls have their own thoughts, sometimes their own feelings. You're not a blade of grass or you wouldn't be asking to begin with.

Maybe having a soul is just being able to ask if you have one?