Barr body is absent in-

Ans. is `b' i.e., Turner's syndrome Barr body (Sex - chromatin) o It is a densely staining inactivated condensed 'X' chromosome that is present in each somatic cells of female. o It is found in the nucleus. o It is used as a test of genetic femaleness ----> it is possible to determine the genetic sex of an individual according as to whether there is a chromatin mass present on the inner surface of the nuclear membrane of cells with resting or intermitent nuclei. Remember following fact and the question will seem very easy. o Chromatid body (Barr body or sex chromatin) is derived from one of the two X-chromosomes which becomes inactivated. o The numer of Barr bodies is thus one less than the number of X-chromosomes. Now see each option one by one o Kleinefelter's syndrome (XXY) --> Two 'X' chromosomes ---> 1 Barr body (2-1). o Turner syndrome (XO) -3 one 'X' chromosome --> No Barr body (1-1 = 0). o Superfemale (X00C) -3 Three 'X' chromosome -3 2 Barr bodies (2-1). Note ? o Barr body is found in female But - Li Kleinefelter syndrome is male with Barr body. Turner syndrome is female without Barr body.