Multiple Choice
In cats, the gene for fur color is located on the X chromosome, with the alleles B (black) and O (orange). Which of the following fur colors are possible in female cats due to X-inactivation?
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2. Mendel's Laws of Inheritance
Sex-Linked Genes
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A researcher observes that a mutant trait appears more frequently in males than in females and that affected fathers do not pass the trait to their sons. Which of the following best explains whether the mutant trait is X-linked?
A
No, the trait is likely autosomal because it appears in both sexes equally.
B
Yes, the trait is likely X-linked because it shows a higher frequency in males and is not passed from father to son.
C
No, the trait is likely Y-linked because only males are affected.
D
Yes, the trait is X-linked because it is only found in females.
Verified step by step guidance1
Step 1: Identify the pattern of inheritance described. The mutant trait appears more frequently in males than females, and affected fathers do not pass the trait to their sons.
Step 2: Recall that males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). Traits on the X chromosome often show different patterns in males and females.
Step 3: Understand that if a trait is X-linked recessive, males are more frequently affected because they have only one X chromosome, so a single mutant allele will express the trait.
Step 4: Note that affected fathers cannot pass X-linked traits to their sons because fathers pass their Y chromosome to sons, not their X chromosome.
Step 5: Conclude that the observed pattern (higher frequency in males and no father-to-son transmission) is consistent with an X-linked trait.
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