organisms and populations

It is the total number of individuals of a species per unit area or volume at a given time. (Such as number of animals per square kilometre or number of trees per area etc.) Population density reflects the success of a species in any given area. Population density (P.D) can be ..

Nitrogen Fixing Organisms - Some bacteria are known to fix the atmospheric nitrogen for their own biological activity. This natural phenomena is commercially utilized to increase the nutrient supply to crops. There are two types of nitrogen fixing bacteria. They are a) Symbiotic N 2 fixin..

Summary - Organic evolution refers to the slow and gradual process by which living organisms have changed from the simplest unicellular form to the most complex multi-cellular forms that are existing today. Organic evolution primarily involves modifications in the exis..

Summary - Smallest unit of ecological hierarchy is the organism, while smallest and basic unit of taxonomic hierarchy is species. A group of individuals, having similar structural and functional characters, capable of potential interbreeding is termed as species. In nature all apecies exh..

The sum of all the populations of same kind of organisms all over the world is called species. Generally, a species is often defined as a group of organisms similar in structure, function and behaviour..

Variation could arise through a process of hybridisation, sometimes even in interspecific hybrids. Genetic variability is necessary for a species to increase its chances of survival. The environment is constantly undergoing changes due to geological and biological processes. Hence, it is necessary..

Where members of two different populations are mutually and actively inhibitory to each other. In such a case competition benefits the organism, which is more suitably adapted while the other is at a disadvantage. The size of population of the latter decreases, finall..

'The amount of organic matter or biomass produced by an individual organism, population, community or ecosystem during a given period of time is called productivity'. Primary production refers to all or any part of the energy fixed by plants possessing chlorophyll. The..

It is the modern theory on organic evolution. It is a synthesis of the ideas from the theory of natural selection and the mutation theory. The theory is the outcome of the thinking of recent biologists such as Huxley, Haldane and Dobzhansky. Neo-darwinism is based on three principles nam..

Structure and function in living systems Reproduction and heredity Regulation and behavior Populations and ecosystems Diversity and adaptations of organisms..