An X-Linked Ichthyosis Is a Recessive Form of a Family

question 48

Multiple Choice

An X-linked ichthyosis is a recessive form of a family of skin diseases caused by a hereditary deficiency of the steroid sulfatase (STS) enzyme. A woman heterozygous for this mutation mates with the phenotypically normal man and produces an XXY son who suffers from the disorder. What kind of nondisjunction can explain this result?

• A)nondisjunction in meiosis I in the mother
• B)nondisjunction in meiosis I in the father
• C)nondisjunction in meiosis II in the mother
• D)nondisjunction in meiosis II in the father

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Definitions:

Spiracles

Small openings on the surface of some animals, especially insects, which lead to the respiratory system, allowing for gas exchange.

Ventilation

The process of actively moving air or water over a respiratory surface.

Tracheal Tubes

Air-conducting tubes in the respiratory systems of some invertebrates, notably insects, facilitating gas exchange.

Opercula

Flap-like structures in certain animals, such as fish, that cover and protect the gills, or the lid covering the opening of a snail's shell.