Biological Species Concept. The biological species concept defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance.Although appearance is helpful in identifying species, it does not define species.Appearance isnt everything.1  Organisms may appear to be alike and be different species. 2  For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each otherthus, they are separate species according to this definition.ppearance isnt everything. 1  Organisms may appear to be alike and be different species. 2  For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each otherthus, they are separate species according to this definition.
Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is an intrinsic property that quantifies how strongly a given material opposes the flow of electric current. A low resistivity indicates a material that readily allows the flow of electric current.
The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor.The inverse quantity is electrical conductance, the ease with which an electric current passes.esistivity and conductivity are reciprocals : . Resistivity is a measure of the material's ability to oppose electric current. This formula is not exact, as it assumes the current density is totally uniform in the conductor, which is not always true in practical situations.