Question

Out of the two X chromosomes of the human female, one X chromosome is inactivated and heterochromatinized. The inactive X-chromosome can be seen as a darkly stained spot and is called as Barr body. Identify the number of Barr bodies that would be seen in the following genotypes.
46 XO, 46 XY, 46 XXY, 46 XXXY

• A. 0,1,1,2
• B. 0,0,1,2
• C. 0,1,2,3
• D. 0,0,1,1

Answer 1

The correct option is B 0,0,1,2

The number of Barr bodies produced in any organism will be one less than the number of X chromosomes in the genotype. The Barr bodies are the inactivated X chromosome. So the number of Barr bodies in the given genotypes are:

46 XO: 0

46 XY: 0

46 XXY: 1

46 XXXY: 2

Thus, the correct answer is option B.