Question

Study the following statements (A - D). Identify the correct statements related to Neo-Lamarckism.

A. It believed that all the acquired characters are passed onto the next generation.
B. It gives importance for use and disuse of organs.
C. As per the theory, germinal variations are transmitted to next generation.
D. There is a direct effect of a changed environment in organisms.

Answer 1

Lamarckism is proposed by Jean Baptiste Lamarck. According to him, suitable changes in characters originating in organisms in response to the environment will be transmitted to the offspring. Modified form of Lamarckism is called Neo-Lamarckism.

Lamarckism believed in the transmission of all acquired characters, that means changes in germ cells and somatic cells will be transmitted to offspring. It gave importance to the use and disuse of organs, meaning the organs which are used more by the organism in the lifetime will develop more. So, statements A and B support Lamarckism.

Neo-Lamarckism believes that those variations that affect germ cells are transmitted to offspring, not the somatic variations (changes in the body cells). Because germ cells are involved in reproduction. Neo-Lamarckism also believes in the direct effect of a changed environment in organisms. For example - white mice reared at high temperature (20-30°C) develop a longer body, long tail and longer hind limbs. At the same time, Neo-Lamarckism discards the theory of use and disuse. So, statements C and D support Neo-Lamarckism.