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.
The ecological niche concept expresses the relationship of an individual or a population to all aspects of its environment. Studies on the relationship between human population and environmental resources have employed niche concept. Ecological niche comprehends all conditions necessary for an organism to exist. Keywords: Niche, Ecology, Environment, Organism . What is ecological niche? 1. The position or function of an organism or a population within a biological and physical environment. 2. The area within a habitat occupied by an organism. The ecological niche is an organism