Question

which statement is true of carriers? select all that apply.
a) they can pass a gene for a recessive disorder.
b) they have one dominant allele.
c) they express the recessive trait.
d) they are heterozygous for a recessive disorder.

Explanation:

• Option A: Carriers (for a recessive disorder) have one copy of the recessive allele, so they can pass it on. Correct.
• Option B: Carriers of a recessive disorder are heterozygous (e.g., Aa for a recessive disorder where aa is affected), so they have one dominant (A) and one recessive (a) allele. Correct.
• Option C: Carriers do not express the recessive trait (the recessive trait is expressed only in homozygous recessive individuals). Incorrect.
• Option D: Carriers are heterozygous (have one dominant and one recessive allele) for the recessive disorder. Correct.

Answer:

A) They can pass a gene for a recessive disorder, B) They have one dominant allele, D) They are heterozygous for a recessive disorder