Question

Which chromosomal abnormality produced by nondisjunction results in an individual whose second sex chromosome is absent?

A. Turner Syndrome
B. Down Syndrome
C. Klinefelter Syndrome
D. Edwards Syndrome.

Answer 1

Turner Syndrome is the chromosomal abnormality where the second sex chromosome is absent, which results in a phenotypically female individual with an XO genotype.

Step-by-step explanation:

The chromosomal abnormality produced by nondisjunction that results in an individual whose second sex chromosome is absent is Turner Syndrome. This condition, where there is only one copy of the X chromosome (an XO genotype), makes the affected individual phenotypically female. Characteristics of Turner Syndrome include short stature, webbed skin in the neck area, hearing and cardiac impairments, and sterility. Unlike Turner Syndrome, Down Syndrome is caused by the presence of an extra chromosome 21 (trisomy 21), Klinefelter Syndrome involves a male having an extra X chromosome (XXY), and Edwards Syndrome is characterized by an extra chromosome 18 (trisomy 18).