Question

If we cut the tail of a mouse, will the tail occur in the next generation of that mouse? Give a reason to support your answer.

Answer 1

Hint: Environmental factors influence genes of the organisms and the acquired changes get transmitted to the next generation. But, the condition is that changes should occur in genes of gametes so it can be passed onto the next generation.

Complete step by step answer: The phenotypic characters of any organism depends on the expression of genes. Expression of a gene is influenced by epigenetic factors. As Lamarck said, acquired characters are passed on to the next generation which was disproved by A. Weismann.

A. Weismann performed an experiment on mice. He cut the tail of newborn mice for many generations i.e. near about 22 generations. But in every generation, the tail disappeared. He could not get tailless mice nor do the mice develop shorter tails. From this experiment, he concluded that the necessity of any organs is not responsible for its development, i.e. the somatic factors are not responsible for the development or growth of any organ. The gametic factors are responsible for the development of any organ. So, changes in the germplasm can only affect the characteristics of future generations.

Additional information: Darwin proposed the ‘theory of pangenesis’. According to his theory, every organ of the body produces minute hereditary particles. Darwin called those particles as pangenesis or gemmules. According to him, gemmules are carried through the blood into the gametes.

Note: Darwin's ‘theory of pangenesis’ was rejected by Weismann’s theory of germplasm. Lamarck’s theory of inheritance of acquired characters or theory of use and disuse of organs was also contradicted by Weismann's theory of germplasm.