What is the expected outcome for the daughters in a cross between a normal male and a carrier female for a sex-linked trait?

What is the expected outcome for the daughters in a cross between a normal male and a carrier female for a sex-linked trait?

• A. All will be normal
• B. All will be carriers
• C. Half will be carriers and half will be normal
• D. None will be affected

Answer: (C)

In a cross between a normal male and a carrier female for a sex-linked trait, particularly one located on the X chromosome, we can analyze the expected outcomes for their daughters. A carrier female has one normal X chromosome and one affected X chromosome (X^NX^n), while the normal male has one normal X chromosome and one Y chromosome (X^NY). The daughters receive one X chromosome from each parent. Thus, from the father, every daughter will inherit the normal X chromosome (X^N), and from the mother, they can inherit either the normal X chromosome (X^N) or the affected X chromosome (X^n). The possible combinations for the daughters are as follows: 1. Inheriting the normal X from the father and the normal X from the mother (X^N/X^N), resulting in daughters who are normal. 2. Inheriting the normal X from the father and the affected X from the mother (X^N/X^n), resulting in daughters who are carriers. In this scenario, there are two equally likely outcomes: half of the daughters will be normal (X^N/X^N) and half will be carriers (X^N/X^n). This leads us to

In a cross between a normal male and a carrier female for a sex-linked trait, particularly one located on the X chromosome, we can analyze the expected outcomes for their daughters.

A carrier female has one normal X chromosome and one affected X chromosome (X^NX^n), while the normal male has one normal X chromosome and one Y chromosome (X^NY). The daughters receive one X chromosome from each parent. Thus, from the father, every daughter will inherit the normal X chromosome (X^N), and from the mother, they can inherit either the normal X chromosome (X^N) or the affected X chromosome (X^n).

The possible combinations for the daughters are as follows:

1. Inheriting the normal X from the father and the normal X from the mother (X^N/X^N), resulting in daughters who are normal.

2. Inheriting the normal X from the father and the affected X from the mother (X^N/X^n), resulting in daughters who are carriers.

In this scenario, there are two equally likely outcomes: half of the daughters will be normal (X^N/X^N) and half will be carriers (X^N/X^n). This leads us to