89.4k views
3 votes
If an X-linked disease results from a rare recessive allele,

A. there will be more females exhibiting the trait than males.
B. there will be more males exhibiting the trait than females.
C. the frequency of affected males and females will be equal.
D. among females there will be more affected than carriers.
E. all sons of affected males will be affected

User Wenchi
by
8.3k points

1 Answer

1 vote

Final answer:

Option B is correct: there will be more males exhibiting the trait than females. This is due to males expressing X-linked recessive diseases when they possess a single recessive allele on their X chromosome, while females must inherit two such alleles.

Step-by-step explanation:

When considering an X-linked recessive disease, the pattern of inheritance is different between males and females due to their chromosomal differences. Males, with only one X chromosome, will express the disease if they have the recessive allele, since there is no second X chromosome to potentially carry a normal allele. This is why males are more likely to show X-linked recessive traits than females. Females, having two X chromosomes, must inherit the recessive allele from both parents to express the disease. If a female inherits only one recessive allele and a normal allele, she becomes a carrier but does not typically show symptoms of the disease.

Answering the student's question, option B is correct. There will be more males exhibiting the trait than females, due to the direct expression of any recessive allele on the single X chromosome males possess, making it much less likely for females to express X-linked recessive diseases unless they inherit the mutant allele from both parents.

User Derric
by
8.6k points