Levels of Organization
Organisms –> populations (species) –> Communities –> ecosystem –> Biome –> Biosphere
Fig : Ecological hierarchy
(i) Organism : An organism is a living unit in nature which performs all the life processes in its body.
(ii) Population : This is a group of organisms of the same species growing in a given area at a particular time.
(iii) Species : Species is formed by all the populations of same kind of organisms. (breeds of dogs are species of dogs)
(iv) Community : Collection of populations of different species that live in a particular area is called community. (various populations of different species in one place)
(v) Ecosystem : It is the sum total of interacting biotic & abiotic factors that are capable of independent existence. (Like a forest)
(vi) Biome : Biome represents large sized ecosystem delimited by specific climate having flora and fauna.
(vii) Biosphere : Any part of earth, where living beings live is called biosphere. The latter involves atmosphere, hydrosphere and lithosphere.
Genetics term was given by W.Bateson. (1905) (Father of Modern Genetics).
Genetics = Branch of biology which deals with the study of heredity and variation
Heredity – Transmission of genetic characters from generation to generation.
Variation – Individuals of same species have some difference, these are called variation.
INHERITANCE : HEREDITY AND VARIATIONS
Heredity : It is the transmission of genetic characters from parents to the offsprings. It deals with the phenomenon of ‘‘like begets like’’ e.g., human babies are like human beings in overall characteristics.
Variations are common in sexually reproducing organisms. Variations are of following two types :
Somatogenic : These are acquired variations and are non-inheritable in nature. The ability of an organism to alter its phenotype in response to environment is called phenotypic plasticity.