Why does a person with normal chromosomes only have two alleles for any single gene trait?
A)A minimum of two alleles is required for the expression of monogenic traits.
B)When a dominant allele is paired with a recessive allele, only the dominant allele is expressed, and the recessive allele is silent.
C)One allele for the monogenic trait is on the paternally derived chromosome, and the other allele is on the maternally derived chromosome.
D)Expression of more than two alleles of any single-gene trait results in enhanced expression of recessive alleles and suppressed expression of dominant alleles.

Question

Quizplus · Accepted Answer

For each single gene at a specific chromosome location, two alleles together control how that gene is expressed even for single-gene traits that have more than two possible alleles. Regardless of how many different possible alleles are present in the entire human population, each person only has two because he or she has only two chromosomes (one inherited from his or her father and one inherited from his or her mother) per pair with one allele on each chromosome. Selection B is true but does not answer the question asked. Only two alleles for each monogenic trait should be present. Both are not required for the expression of all monogenic traits.

Why Does a Person with Normal Chromosomes Only Have Two