The simplest grouping of more than one kind of organism in a biosphere is a community.

Here's why:

* Biosphere: The entire region on Earth where life exists, including all living organisms and their environments.

* Ecosystem: A community of interacting organisms and their physical environment.

* Community: A group of different populations of species living and interacting in the same area.

* Population: A group of individuals of the same species living in the same area.

So, a community is the smallest grouping that includes multiple species interacting with each other.