Gas exchange is the process by which oxygen and carbon dioxide (the respiratory gases) move in opposite directions across an organism's respiratory membranes, between the air or water of the external environment and the body fluids of the internal environment.
niche. The function or position of a species within an ecological community. A species's niche includes the physical environment to which it has become adapted as well as its role as producer and consumer of food resources.
Fundamental: Realized niche: Laymenâs definition: Is a scenario where a species is able to survive at optimum level: Is realized scenario where an organism is able to survive with factor relating to predation,competition or human factor: Definition: Range of conditions in the environment in which a species survives