Nondisjunction involving the X chromosomes may occur during oogenesis and produce two kinds of eggs.If normal sperm fertilize these two types, which of the following pairs of genotypes are possible?
A)XX and XY
B)XXY and XO
C)XYY and XO
D)XYY and YO
E)none of these

Question

Quizplus · Accepted Answer

Nondisjunction during meiosis I in oogenesis can result in one egg receiving two copies of the X chromosome and the other egg receiving no X chromosome. This results in the production of two types of eggs: one with an XX complement and one with an X0 complement. If these two types of eggs are fertilized with normal sperm carrying either an X or a Y chromosome, the possible genotypes of offspring are XXY (Klinefelter syndrome) or XO (Turner syndrome). Therefore, the only possible pair of genotypes among the given options is XXY and XO, which is choice B. The other pairs of genotypes (XX and XY, XYY and XO, XYY and YO) are not possible outcomes of fertilization involving the two types of eggs resulting from X chromosome nondisjunction during oogenesis.

Nondisjunction Involving the X Chromosomes May Occur During Oogenesis and Produce