Answers (1) Jewels Vern. Energy is sometimes defined as capacity to do work. But work is defined as disordering energy. So energy is capacity to do disordering energy. That is a circular definition. Energy is not a physical unit. It is a philosophical concept and an accounting technique used to analyze mechanical and chemical exchanges. In nuclear physics it is defined as a wavelength of light, in biology it is a synonym for metabolism, and in public utilities they say energy when they mean connectivity. Anybody who uses the word in any other context does not know what he is talking about.
A species is often defined as the largest group of organisms where two hybrids are capable of reproducing fertile offspring, typically using sexual reproduction. While in many cases this definition is adequate, the difficulty of defining species is known as the species problem.his definition can be extended to say that a species is a group of organisms that could potentially interbreedâfish could still be classed as the same species even if they live in different lakes, as long as they could still interbreed were they ever to come into contact with each other.
A species is a category within the classification system. Living things of the same type belong to the same species. For example, humans are one species and dogs are another species.