Chapter: Energy Flow
Sun as the principle source of energy
Sun is the principle source of energy for all the living organisms. There are two main types of energy from the sun, the light energy and the heat energy. The light energy from the sun is trapped by photosynthetic plants and some of the bacteria and converted into chemical energy.
Non-cyclical nature of energy flow
All the organisms obtain their energy directly or indirectly from the sun. This energy is passed on from one organism to the other organism through food chain. But unlike water and elements such as carbon and nitrogen energy does not return in a cycle. Energy that is produced out by the organisms is transferred to the environment. Feeding is the most common interaction between different organisms in an eco-system. During feeding, one organism is obtaining energy and raw materials from the other organism. Usually one organism feeds on the other but later it may itself be the food for a third species. The flow of energy between different organisms in an ecosystem can be shown in a food chain.
Energy transfer is inefficient
The amount of energy passed on in a food chain is reduced at every step. Since energy can neither be created nor destroyed it is not lost, but is converted into some or the other form. During respiration, some energy transferred to the environment as heat.
Let us look into the flow of energy
- Sunlight provides the light energy to drive the food chain.
- The light energy is utilized by producers, mostly green plants. The green plants convert light energy into chemical energy in food compounds.
- Consumers are the organisms that obtain food from other organisms. Primary consumers which are usually herbivores obtain their energy by feeding on green plants.
- Secondary consumers which are usually carnivores feed on primary consumers for their food.
- Secondary consumers may be eaten by eaten by tertiary consumers which are usually the top carnivores.
- Decomposers, like fungi and bacteria obtain their energy and raw materials from the animal wastes and remains of the other organisms (dead bodies).