Photosynthesis is the process.
The five main external factors that must be present or provided t sustain life are:
1. Water
2. Oxygen
3. Food
4. Atmospheric temperature
5. Atmospheric pressure
<span>The human body needs water, food and oxygen in order the body functions to work properly.
</span>Not every temperature is temperature at which the human can live. For example: we can not stay alive long period of time at temperature of 60 degrees Celsius.
