Question

a persons rh type results from the combination of two possible alleles, a ____ one that codes for the factor, and a ____ one that does not.

• dominant/recessive
• codominant/recessive
• recessive/codominant
• recessive/dominant

Explanation:

To solve this, we recall genetics concepts: Dominant alleles express their trait (here, coding for the Rh factor), while recessive alleles are masked unless both are present (and do not code for the factor here). Codominance involves both alleles expressing, which doesn't fit. So the first allele (coding for the factor) is dominant, the second (not coding) is recessive.

Answer:

A. dominant/recessive