Biology lesson 05-Energy flow in ecosystems - Energy Flow in Ecosystems 1 The Sun Source of all life All life on earth ultimately depends on the sun The

Biology lesson 05-Energy flow in ecosystems - Energy Flow...

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Energy Flow in Ecosystems : 1. The Sun: Source of all life All life on earth ultimately depends on the sun. The sun provides the light energy which powers photosynthesis, the source of energy used by plants. Photosynthesis: The process by which green plants use sunlight, water, and carbon dioxide to produce glucose and oxygen: CO 2 + H 2 O + energy ——> C 6 H 12 O 6 + O 2 Of all the energy from the sun that reaches earth, only a tiny fraction – 0.023% – is actually used by plants for photosynthesis. The rest is either reflected into space, used to warm the air or water, or generate wind. Albedo: The degree to which light is reflected by a surface. The higher the albedo, the more light is reflected. Example: Snow has an albedo of 0.80–meaning 80% of sunlight is reflected. A typical forest has an albedo of 0.03 to 0.05, meaning only 3 to 5% of light is reflected–the rest is absorbed by the plants. Anything that increases the albedo of an area DECREASES the amount of light the plants can use. Clouds reflect light, as does snow, and anything that causes water vapour to form, or that adds dust to the air, also increases albedo.
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