The organism and the physical environment of the habitat form an ecological complex called :

Among the following which is a nitrogen fixing bacteria ?

Which is an essential element required by organisms to synthesize proteins and nucleic acids ?

The energy trapped by green plants is relayed through a series of heterotrophic organisms, this process is called :

Among the following which one is a biotic component ?

One gallon is equivalent to :

All organic compounds contain :

Name the organism which is involved in denitrification ?

Water vapour formed by transpiration and respiration form :

The life sustaining zone of earth, where lithosphere, hydrosphere and atmosphere interact is called :