A dynamic complex of plant, animal and microorganism communities and their non-living environment all interacting as a functional unit.
An organ or cell that acts in response to a stimulus
Rate of flow of electric charge .
(of a species) seriously at risk of extinction
A species which is at risk of becoming extinct because it is either few in number, or threatened by changing environmental or predation parameters
Data which has been shown to be valid.
The act of ending the existence of a plant or animal