(a) The law of dominance states that the allele expressed in the heterozygous condition is termed as dominant and the allele which cannot express itself in the heterozygous condition is called as recessive. Recessive traits are expressed only in homozygous recessive conditions. Let us take an example of tall and dwarf in pea plant. When pure line tall (TT) plant were crossed with pure line dwarf (tt) plants, offspring were all heterozygous tall (Tt). Hence, allele tall (T) is dominant over allele dwarf (t) which is recessive in nature.
(b) The traits acquired during life time of an individual are not inherited because the traits acquired during life time of an individual include his unique hair styles, different type of dressing, consumption of different types of foods, etc. Such traits are not inherited by their progeny it is because these are the changes which do not have any effect on DNA of the germ cells. Any change which affects the DNA arrangement of the germ cell may lead to transfer of the mutation to the progeny cells. The traits acquired by the individual during his life time are practiced by him due to the situation and the environment in which he/she lives after birth. As the traits acquired during life time of an individual does not interfere with the genetic makeup of the DNA of the germ cells, they are not inherited.