Question

a woman is a carrier for two recessive genetic conditions: one is carried on chromosome 5, and one is carried on the x chromosome. which of the following statements is true regarding the inheritance of these two traits?
correct answer(s)
the trait carried on the x chromosome is more likely to be expressed in a son than in a daughter.
the allele carried on the x chromosome can be inherited by an offspring of either sex.
the allele carried on chromosome 5 can be inherited by an offspring of either sex.
a son is more likely than a daughter to inherit the recessive allele carried on the mothers x chromosome.
incorrect answer(s)

Explanation:

• For X - linked recessive traits: Sons have only one X chromosome (from mother). If the mother is a carrier (heterozygous), sons have a 50% chance of getting the recessive allele and expressing the trait. Daughters have two X chromosomes (one from mother and one from father). To express the X - linked recessive trait, they need the recessive allele from both parents. So the trait carried on the X chromosome is more likely to be expressed in a son than in a daughter. Also, sons and daughters can inherit the X - linked allele (sons get X from mother, daughters get one X from mother).
• For autosomal (chromosome 5) recessive traits: Since chromosome 5 is an autosome (not sex - chromosome), offspring of either sex can inherit the allele from the mother.

Answer:

• The trait carried on the X chromosome is more likely to be expressed in a son than in a daughter.
• The allele carried on the X chromosome can be inherited by an offspring of either sex.
• The allele carried on chromosome 5 can be inherited by an offspring of either sex.
• A son is more likely than a daughter to inherit the recessive allele carried on the mother’s X chromosome.