Principles Of Inheritance And Variation

Answer (d) Super female

The law of independent assortment applies only to gene pairs on different pairs of homologous chromosomes - one gene pair on one pair of homologous chromosomes and the other gene pair on another pair of homologous chromosomes. Though Mendel did not know about chromosomes, all the traits he studied were on different pairs of homologous chromosomes. That is why he concluded that gene pairs segregate independently of one another. Mendel�s gene pairs did not show linkage. Linkage is the phenomenon of certain genes staying together and their inheritance from generation to generation without any change or separation due to their being present on the same chromosome.

Mutation can be artificially induced with the help of mutagenic agents which can be broadly classified as - (a) Physical mutagens (b) Chemical mutagens. Physical mutagens are mainly radiations like X rays, gamma rays, beta rays and neutrons. High temperature also causes mutations. Aminopurine is a chemical artificial base analogue of adenine. It can substitute adenine as well as can pair with cytosin. Similarly nuclear reaction cause great impact on the DNA and mutations are noticed in several generations due to nuclear reaction or explosion. Low temperature does not cause mutation.

Answer (b) Recessive gene on X-chromosome

Answer (d) Sex-linked recessive inheritance