CBSE Class 10 Science 2017 · Paper 31/2 · Question 11

Examples: (1) A person who learns to swim, dance or speak a new language acquires the skill by practice; their children are not born with it and have to learn it themselves. (2) A person who builds strong muscles by regular exercise does not have children born with strong muscles; similarly, a person who loses a finger in an accident has children with normal fingers. Reason: these experiences and traits change only the non-reproductive (body) tissues — the brain, the muscles, the skin — and not the DNA of the germ cells. The next generation develops from a zygote formed by the fusion of gametes, so it receives only the DNA of the germ cells, and changes in body tissues cannot be passed on to it. Such traits are acquired traits and are not inherited. Such traits can be passed on only when the change occurs in the DNA (the genes) of the germ cells, that is, in the reproductive tissue.