Question

How many Barr bodies are present in an individual with Klinefelter syndrome (XXYY)?

1) 0
2) 1
3) 2
4) 3

Answer 1

An individual with Klinefelter syndrome (XXYY) has two Barr bodies since two of the X chromosomes undergo inactivation to form Barr bodies.

Step-by-step explanation:

Individuals with Klinefelter syndrome exhibit an abnormal number of X chromosomes, with the XXY genotype being one common form. According to the specifically referenced information, every X chromosome except one undergoes inactivation in Klinefelter syndrome, which is evident by the presence of Barr bodies. In the case of an XXYY individual, who presents with Klinefelter syndrome, two of the X chromosomes would be inactivated to form Barr bodies, leaving one X and one Y chromosome active, similar to normal male XY cells.

Therefore, the correct answer to the question 'How many Barr bodies are present in an individual with Klinefelter syndrome (XXYY)?' is option 2.