The niche that an organism occupies is the opening in the environment that the organism fills to make a living. A species' niche is its place in an ecosystem relative to the other organisms present. More »

A niche is the role an organism fills within its environment. What and where an animal eats are considered part of its niche. For instance, some birds, such as woodpeckers, eat insects in trees. This limits the bug popul... More »

In biology, "form follows function" means that, within an organism, structures are formed in direct correlation to what they are meant to do. For example, a cat's paw and a human hand have similar bones, but each are des... More »

In biology, a vector is any organism that facilitates the spread of a disease. Vectors do not inherently cause diseases but are mere vehicles of the germs that cause disease. Vectors may include small insects or larger a... More »

A multicelled, or multicellular, organism is any living being comprised of more than one cell. Typically, multicellular life differentiates cells into specialized tasks, which in larger organisms can form tissues and org... More »

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A physiological change is a change in the normal function of a living organism. An example of a physiological change is the everyday shedding of dead skin cells in humans. More »

Nonpathogens are usually harmless microbes that inhabit a living organism, such as Staphylococcus aureus and candida. Some nonpathogen microbes are bacteria that can be beneficiary for the human organism, such as lactic ... More »