In human female, barr bodies are formed by
Inactivation of mother's $X$ chromosome
Inactivation of father's $X$ chromosome
Inactivation of both mother's and father's $X$ chromosomes
Inactivation of either mother's or father's $X$ chromosome
Mirabilis jalapa is a good example of
The evidence that crossing over occurs at four stranded stage and not at two stranded stage of the chromosomes, comes from
Match the columns :
Column $I$ |
Column $II$ |
$(1)$ Lethal mutation | $(a)$ Mutation caused by external factors |
$(2)$ Spontaneous mutation | $(b)$ They are metabolic errors |
$(3)$ Induced mutation | $(c)$ As a result the mutant dies |
$(4)$ Biochemical mutation | $(d)$ Most of the mutations occurs in nature are of this type. |
If in a child of $10$ years ages of the intelligence is of $14$ years child, the $I.Q.$ of this child would be