The Living Environment Summary

The living environment: part 1

Conditions needed for life on Earth

Many abiotic factors make it possible for life to survive. When Earth formed 4 billion years ago, many of its physical features made the appropriate conditions to support life. Its position in the solar system; size; structure; composition and rotation combined to create the conditions following its birth. These are some of Earth's physical features which make it possible for life to survive:

• The gravational forces between Earth and the moon creates tides and causes the Earth's orbit to be almost upright in relation to the sun.
• The mass of Earth is big enough to control gravity which is large enough to retain an atmosphere.
• The tilted orbit of Earth around the sun creates seasonal fluctuations in climatic conditions.
• Earth's distance from the sun controls inoculation which allows water to exist in its liquid and solid state.
• Earth's magentic field deflects harmful radiation which is emitted from the sun.
• The speed of rotation prevents excessive temperature variations.

One of the abiotic factors which is essential for all life on Earth is water because of water's role in the physiological processes of organisms and for the way it changes the wider environment. Below are explainations of why water is a condition needed for life on Earth:

• Water acts as a physiological solvent. Many of the molecules involved in chemical reactions in cells are dissolved in water.
• Water is used as a solvent in blood and plant sap and is needed to transport molecules around the organism for example protein, amino acids, mineral nutrients, sugars, carbon dioxide, oxygen and waste products.
• Water is used to regulate heat loss for example water can be evapourated off the skin which causes heat loss. Heat can also be transported to other parts of the body for example heat is transported from the core of the body to the extremities to lose heat.

Here are some explainations as to how water can change the wider environment and how this is important to sustain life on Earth:

• An unusual feature of water is that upon freezing, water expands. This means that because ice floats, ice can trap very cold air above it and prevent it reaching and cooling the water beneath. This means that lakes do not freeze over in winter in cold places so that life in aquatic systems is able to survive during winter.
• Water has a high specific heat capacity so that it warms and cools slowly. This means that the size and rate of temperature changes can be controlled which allows water to exist in its liquid and solid state.
• Water provides aquatic ecosystems for organisms such as ponds and lakes.

There is a suitable temperature range at which life can exist. Life usually exists in places which have a temperature higher than 0℃ but lower than 40℃.

Life usually exists in places higher than freezing point because below 0℃, water can only exist in its solid form. However life usually…