NEET Biology question

In the Barr body (sex-chromatin) of a normal female

(A)One X-chromosome, chosen strictly by parental origin (always the paternal one), always becomes inactive
(B)The Y-chromosome forms the Barr body
(C)Heterochromatin condenses near the centre of the nucleus to form the Barr body
(D)One of the two X-chromosomes becomes inactive at random (irrespective of parental origin) and forms the Barr body near the nuclear membraneCorrect

Answer: (D)

Solution

In a normal female (XX), one of the two X-chromosomes in each somatic cell is inactivated at random with respect to its parental origin (the Lyon hypothesis) and condenses into a Barr body visible as a darkly staining mass near the nuclear membrane, matching

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Question ID VK-119700