Animals consume the food synthesized by plants.
Plants provide food and shelter for animals, and as they photosynthesize, regulate the levels of oxygen and carbon dioxide in the atmosphere.
Animals inhabit almost every part of the biosphere with their amazing diversity of habitat, form, and function. An exhaustive knowledge of the structure of an animal imparts a lot of information about the various functions it is capable of performing.
Discerning knowledge of animal structure and physiology is obtained by observing the activities of the organ systems, organs, tissues, and cells of animals. Usually animals are extensively used for experiments in scientific laboratories to determine how altered conditions affect its physiological conditions and the results are compared with the human physiological conditions. In addition, the activities of healthy organs are often compared with those of diseased ones.
Much knowledge of human physiology has been obtained by studying animals, as animals form the models for studying human beings. Thus, most aspects of human physiology are closely analogous to corresponding aspects of animal physiology, and animal experimentation has provided much of the foundation of physiological knowledge.
In animal biotechnology, advanced techniques are being used to improve genetics and for pharmaceutical or industrial applications of animals. Molecular biology techniques can help drive breeding programs by directing selection of superior animals. Animal cloning has been the subject of scientific experiments for many years, but didn't prove to be true until the birth of the first cloned mammal in 1997 - a sheep named Dolly. Since Dolly, several scientists have cloned other animals, including cows and mice.
Thus, using recombinant DNA technology, it can be possible to alter the genetic makeup of an organism (including animals) for selected purposes, producing therapeutic proteins in cows and goats, producing transgenic animals and improving the animal variety.