Ecology Notes (NEET)

Definitions

Population - A group of organisms from the same species who are living together at the same time in the same place that if reproducing sexually can interbreed.

Community - All the populations of different species living together in one area at the same time.

Habitat - The place where a organism species, population or community is living.

Ecosystem - All the communities as well as non-living parts of an area together make up an ecosystem.

Biosphere - All of earth’s ecosystems together make one large ecosystem known as the biosphere.

Producers - Plants and some photosynthetic bacteria who transfer energy from the sunlight into organic compounds which in most cases take the form of carbohydrates.

Consumers - All organisms who consume the energy created by the producers either directly or indirectly.

Productivity - The amount of energy in each organism in each trophic level over a set period of time.

Energy flow:

(1) The transfer of energy from one trophic level to another trophic level is called energy flow.

(2) The flow of energy in an ecosystem is unidirectional. That is, it flows from the producer level to the consumer level and never in the reverse direction. Hence energy can be used only once in the ecosystem.

(3) But the minerals circulate and recirculate many times in the ecosystem.

(4) A large amount of energy is lost at each trophic level.

(5) It is estimated that 90% of the energy is lost when it is transferred from one trophic level to another.

(6) Only about 10% of the biomass is transferred from one trophic level to the next one is a food chain. And only about 10% of chemical energy is retained at each trophic level. This is called 10% law of Lindeman (1942).