Most textbooks describe it as meeting 5 main criteria…
1. ability to adapt to its environment
2. ability to reproduce on its own
3. grows and develops
4. made of cells
5. uses resources/a source of nutrients.
I’ve always contemplated a 6th tenet, which would be “uses a genetic code ie. DNA, RNA” and have always thought the 2nd tenet as bogus.
Viruses cannot reproduce on its own and must use a host cell to reproduce. There is some grey area as to whether a virus is considered living or not. However, mules cannot reproduce (because they have an odd number of chromosomes) and thus they would also be considered not living.
What do the other scientists of the world think?