biosphere – all regions on earth where life exists

(Pronounced buy-oh-sfeer)

To remember the meaning of biosphere, use the following mnemonic:

I'd like to buy a sphere (biosphere) with a region of life in it. 

The biosphere refers to the regions on earth where all living organisms exist and interact with each other and their environment. It includes all life on land, in water, and in the air, extending from the deepest ocean trenches to several kilometres up in the atmosphere where some microorganisms can survive. The biosphere encompasses all ecosystems on earth, from tropical rainforests and coral reefs to deserts and polar regions, and represents the global sum of all living things and their habitats. Within the biosphere, organisms are constantly cycling carbon, nitrogen and water, creating the survivable environment required for life on earth. 

Maybe an easy way to remember biosphere is to think of what isn't a biosphere on earth, what isn't a place for organisms. This includes:

• Volcanic areas.

• The deep crust and mantle of the earth.

• The extreme cold of the polar regions. 

• The highest mountain peaks. 

• The deepest ocean trenches. 

These areas lack the necessary conditions for life.