Earth’s components

The Hydrosphere – includes all the water found on Earth (Lakes, ponds, oceans ice caps and even water vapour in the air. All organisms depend on water for their metabolism; most chemical reactions take place in water. (Remember Hydro means water in Greek.)

The Atmosphere – the envelope of air that surrounds the Earth. It is often subdivided into four zones (called from lowest altitude to highest: the troposphere, stratosphere, mesosphere and thermosphere) (Remember atmos means air or vapour in Greek.)


The Lithosphere – the outermost solid layer of Earth, its crust and upper mantle. It is made of the large mobile plates we studied in geology both land masses and under the ocean floor. In this topic we will be most interested in the rock and soil types. (Remember litho means rock in Greek.)


These entire three systems link together to form a Biosphere, a region that supports living things (or biota.) It is common to subdivide the Biosphere into regions characterised by their main plant types.

These regions called Biomes include deserts, tundra, tropical rainforest, savannah, and alpine areas.

The Ecosystem describes the way organisms are found together in a physical place. Both physical (abiotic) and biological (biotic) factors describe an ecosystem. Examples of abiotic factors may be: wind speed, humidity, rainfall, soil type, air temperature etc. While biotic factors may include the presence of producers, parasites, competitors, pathogens and decomposers in the community