Multiple Choice
In the snail Cepaea nemoralis, which of the following best describes the inheritance pattern of shell color, which is determined by an autosomal gene?
3
views
2. Mendel's Laws of Inheritance
Sex-Linked Genes
Struggling with Genetics?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
If five males inherit an X-linked recessive allele from their carrier mothers, what is the expected phenotype of these males?
A
All five males will be carriers but not express the trait.
B
None of the males will express the recessive trait.
C
Only half of the males will express the recessive trait.
D
All five males will express the recessive trait.
Verified step by step guidance1
Understand that X-linked recessive traits are carried on the X chromosome. Males have one X and one Y chromosome (XY), so they have only one copy of the X chromosome.
Recognize that if a male inherits an X chromosome carrying the recessive allele, he will express the trait because there is no second X chromosome to mask the effect (no dominant allele present).
Recall that females have two X chromosomes (XX), so a female carrier has one normal allele and one recessive allele, but typically does not express the trait because the normal allele is dominant.
Since the problem states that five males inherit the X-linked recessive allele from their carrier mothers, each male receives the affected X chromosome from the mother and a Y chromosome from the father.
Therefore, all five males will express the recessive trait because they each have only one X chromosome, which carries the recessive allele.
Related Videos
Related Practice
Sex-Linked Genes practice set
Problem sets built by lead tutorsExpert video explanations