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.
DEFINITION of 'Hard Skills'. Specific, teachable abilities that can be defined and measured. By contrast, soft skills are less tangible and harder to quantify. Examples of hard skills include job skills like typing, writing, math, reading and the ability to use software programs; soft skills are personality-driven skills like etiquette, getting along with others, listening and engaging in small talk.