What is required for life to be possible? The birth and existence of life requires:

• water in liquid form
• elements that render life possible, such as carbon, hydrogen, nitrogen, oxygen and phosphorous
• a source of energy, such as the Sun.

There can be no life without energy. Energy is used to construct complex chemical compounds, to move, and to make different things happen. All life on planet Earth receives most of its energy from the Sun. 

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Plants need water and sunlight, among other things. Animals require water as well as energy produced by plants.

Plants, algae and some bacteria are capable of photosynthesis. This means that they can make use of light energy from the Sun to produce chemical energy and store this energy in chemical compounds. All other organisms are dependent on the chemical energy produced by plants. 

The solar energy bound by green plants and other producers moves through the food chain and is used by consumers, such as herbivores and predators.

All life on planet Earth is organic. This means that it is based on different carbon compounds. Carbon is an element that can form a variety of molecular structures, such as chains and wheels. 

The molecules that are significant for living organisms, such as carbohydrates, fats, and proteins, are comprised of carbon chains that have joined together with elements such as hydrogen, nitrogen and oxygen. To thrive, life also requires other elements, such as phosphorous, potassium, calcium, magnesium and iron. 


Solar energy is bound into chemical energy by plants. This chemical energy is used by herbivores and other consumers.