The answers are nutrition and procreation.
every living being has two objectives during his life:
* Feeding to ensure its own growth: Bacteria, parasites, fungi, Animals, and plants are living beings. They need water and food to live.
* To procreate oneself in order to ensure its progeny during the next generations: One of the most fundamental abilities of a living being is to reproduce, that is what differentiates the inert from the living. The smallest living unit able to reproduce is the cell which, by dividing, autonomously generates two daughter cells. In an indisputable way, we can speak of being alive from the cell: bacteria are cells, fungi are unicellular or multicellular, plants and animals are multicellular.
