Energy Flow, The Power Behind Life

 

What is Energy Flow?

Energy flow is the movement of energy through an ecosystem, starting from the Sun and moving through different organisms. All living things depend on energy to survive, grow, and reproduce.

• Key Idea: Energy flows in one direction and cannot be recycled!

 

The Sun: The Ultimate Energy Source 

• The Sun is the main energy source for almost all life on Earth.
• Plants and algae use sunlight during photosynthesis to convert light energy into chemical energy (stored in glucose).
• This energy is passed through food chains and food webs.

 

How Does Energy Flow?

Energy moves through ecosystems in this order:

1. Producers (Plants):

   • Plants capture sunlight and turn it into food (glucose) through photosynthesis.
   • Example: A sunflower captures sunlight to make its food.

2. Consumers:

   • Herbivores eat plants to get energy.
   • Carnivores eat herbivores to get energy.
   • Omnivores eat both plants and animals for energy.
   • Example: A rabbit eats grass; a fox eats the rabbit.

3. Decomposers:

   • Fungi and bacteria break down dead organisms, releasing nutrients back into the soil and energy into the environment as heat.
   • Example: Mushrooms breaking down a fallen tree.

 

Energy Transfer in Ecosystems

• At every stage of the food chain, some energy is lost:
  1. Used for Life Processes: Energy is used for movement, growth, and reproduction.
  2. Lost as Heat: Energy is also lost to the environment as heat.

 

Efficiency of Energy Flow

Only 10% of energy is transferred from one level of the food chain to the next. The rest is lost as heat or used up.

• Example Calculation:
  • A plant stores 10,000 J of energy from sunlight.
  • A rabbit eats the plant and gets 1,000 J of energy.
  • A fox eats the rabbit and gets only 100 J.

 

Energy Flow Diagram

Stage	Energy Source	Example
Sun	Light energy	Sunlight
Producer	Converts sunlight to glucose	Grass or trees
Primary Consumer	Eats producers	Rabbit
Secondary Consumer	Eats primary consumer	Fox
Decomposers	Break down dead matter	Fungi or bacteria