Conditions for life on Earth.

The position, size, structure, rotation and location of the Earth combined, has allowed life to develop around 4 billion years ago.

Water has many functions, such as:

• It is a Physiological Solvent, where chemical reactions take place in water.
• It is used for Transport, transporting oxygen, carbon dioxide, sugars, amino acids, waste products and mineral nutrients.
• And it is also used for Temperature Control, the evaporation of water from the skin to cool the body when it is too hot!
• Also provides Aquatic habitats, such as rivers, lakes and oceans.

Earth, also has an Appropiate Temperature Range, as most areas of Earth have temperatures above 0 degrees celcius, allowing liquid water to be present.

As well as water, and temperature, it has suitable Ambient Gases, which includes; carbon dioxide, oxygen and nitrogen, and are used for photosynthesis and protein synthesis.

The distance from the sun, controls light levels.

The rotation of the Earth, produces the day and night cycles.

The tilt of the Earth's axis produces seasonal changes.

The molten layers beneath the crust, produces the Earth's magnetic field, reflecting the sun's harmful radiation.

The first oxygen came about, by the Photolysis of water ( Splitting of molecules by light, includes splitting the water molecules in the atmosphere to produce oxygen ).

After that, Photosynthetic bacteria started to produce the oxygen and up to the present day Photosynthetic plants produce larger amounts of oxygen.

This oxygen in the atmosphere absorbed UV light, which split the oxygen molecules, producing monatomic oxygen, which reacted with diatomic oxygen, providing with out Ozone we have today, protecting us from the harmful UV radiation.

Before the Ozone layer was developed abundant life was not possible on land, due to the UV rays, so the first signs of life started in the oceans.

Without any carbon dioxide, the Earth would be too cold for life to exist as it traps heat, however, too much carbon dioxide would cause temperatures to rise too high for life to remain.

Living organisms have helped keep the atmospheric temperatures suitable, by removing Carbon Dioxide from the atmosphere and storing the carbon in fossil fuels and carbonate rocks, such as limestone and chalk.

All the Individual features of the Earth and their inter-conntections can be very complex. However, you may find it easier to focus on one aspect at a time; The Lithosphere, Biosphere and Hydrosphere.