|CA GR.9-12 6.f.|
For the ecosystem to function energy must be available and it must be transferred. Why? Because of the First and Second Laws of Thermodynamics. The First Law states that energy can neither be created nor destroyed, but can be converted from one form to another. The Second Law states that everything is running downhill or, more formally, everything in the universe is going from a more organized state to a less organized one.
To illustrate these laws, let's consider a car with a full tank of gasoline. The gasoline is burnt, the car goes, and the gasoline is broken down into gases and heat, but, following the First Law, the total amount of energy is constant although now it is in a different form, namely heat. Heat is a very disorganized form of energy. However, what of the Second Law? It, too, has been operating.
Life exists because it has found a way to reverse the Second Law of
Thermodynamics, if only temporarily, but, to do this, living things need
constantly to invest energy. There is, however, only one energy source
available to earth’s organisms and that is the sun. Photosynthesis is the
only means available to use this source energy. Autotrophs are organisms
that produce their own food through photosynthesis.
Any ecosystem can be viewed as consisting of producers (the autotrophs) and consumers (heterotrophs). These concepts are the bases of the ECOSYSTEM PYRAMID OF ENERGY.
autotrophs form the basis of the pyramid and are the primary
producers. The next level is heterotrophs that consume the autotrophs and
are the primary consumers. Generally, 10% of the energy is based from one
level to the next.
Decomposers that break down the remains of plants and animals also
figure into pyramid of energy. Detritus food chains transform litter back
FOOD WEBS illustrate the complex interaction of organisms in the various pyramids. The movement of energy from one trophic level to the next or through the food web is shown in the ENERGY-FLOW DIAGRAM.
Photosynthesis limits productivity of the ecosystem. The net primary production is the gross production minus the energy and carbon compounds lost by plant respiration. The factors that limit primary productivity are temperature and water, mineral nutrients, light and carbon dioxide.
Here are 12 ecology-related experiments for you to try:
Build a small ecosystem and make a mold terrarium, watch tiny blue, green
and white plants grow on leftover food.
Create this your own food chain and energy pyramids