Consider the illustration below:

The biosphere is all living components of the earth (humans, plants, animals, bacteria, fungi, protists, and all microscopic organisms on land, in the air, and in the oceans). It also includes all organic matter that has not yet decomposed. This living part is hugely dependent on the other three spheres.

The hydrosphere provides moisture or water to plants and animals, the geosphere provides the solid surface on which animals and plants grow and also provides heat from beneath the earth.

The atmosphere provides the gasses (nitrogen, oxygen, and carbon dioxide) needed by living things. The atmosphere also provides the screen from the sun’s UV radiation and helps us receive just enough of the sun’s heat.

It is believed that the biosphere is exclusive to earth alone. Scientists believe there are traces of water, rock, and gases on other planets, but no life has been found yet. Humans are exploring other planets to see if this idea is correct.

The interaction of the biosphere with other spheres can be explained better by a theory known as Ecosystems.