theories of heredity

Pre-Mendelian Theories on Heredity - There have been several explanations on the possible mechanism of inheritance of traits from the parent to the offspring, put forth from time to time by different biologists. All these early theories presume that the characteristics..

There have been several explanations on the possible mechanism of inheritance of traits from the parent to the offspring, put forth from time to time by different biologists. All these early theories presume that the characteristics of the two parents somehow mix during inheritance...

Summary - The mechanism of transmission of characters from the parental generation to the offspring is called heredity. The differences seen among members of a species and their offspring are described as variations. Genetics is the study of heredity, variations and the environm..

The Greek philosopher and mathematician of 6 t h century BC, Pythagoras proposed the idea that each organ in the body of an animal released some kind of vapour, and that the new individual is formed by the combination of vapours from different organs. Fig. 18.1 Pythago..

Aristotle, the famous Greek philosopher was of the opinion that menstrual fluid produced by women is the impure female semen. These fluids combine at the time of mating. He also held that the female semen just provides the inert substance while the vital ingredient required for the formation of an ..

The earlier belief on heredity was that characteristics of the two parents mix and express in the offspring. These ideas came to be known as the blending theory of inheritanc..

Heredity depends upon the protoplasmic continuity between the parent and the offspring. It is the gametes that establish the continuity between parent and offspring and hence, the mechanism of inheritance operates across this exceedingly slender protoplasmic bridge. The machinery of inher..

All these evidences point to the fact that evolution occurs. The exact mechanism of evolution, however, is not yet conclusively proven. But constant study and research in the above fields is continuing for answers. Asexual reproduction results in identical offspring whereas sexual reproduction..

The modified form of cell theory is called cell principle. It applies almost completely and universally to living organisms. The cell principle is also called cell doctrine. Following are the statements of cell principle. Life exists only in cells. Living organisms may be composed of a si..

Evolution and Classification - In spite of many evidences, studies and theories, we are still not aware of how the evolution actually occurs. If we go backwards at some point in the history of the earth it would have consisted of only the basic elements, the non-living materials like the ..