The Sun as a Source of Energy (Cambridge O Level Biology)

Transfer of Energy

• The Sun is the principal source of energy input to biological systems
  
• All energy transfers on Earth can be traced back to the Sun
• Solar energy powers photosynthesis
  • So all life depends, directly or indirectly, on photosynthesis

Flow of Energy from the Sun to Earth Diagram

Around half of the Sun's energy that enters the atmosphere reaches the surface. Some of this energy powers photosynthesis which all life depends upon.

• Energy flows through living organisms
  • Including light energy from the Sun and chemical energy in organisms
  • Energy is eventually transferred to the environment eg. as heat