A carrier is a person who has
A. one recessive and one dominant allele for a trait
B. two recessive alleles for a trait
C.two dominant alleles for a trait
D. more than two alleles for a trait (my answer)
An organism's genotype represents the two alleles inherited for a given trait. For an organism to be a carrier, the genotype must include one copy of a recessive allele. Carriers do not exhibit the physical trait, but have a 50 percent chance of passing the gene on to an offspring.
A
B
C
D
The correct answer is B. two recessive alleles for a trait.
A carrier is a person who carries a recessive allele for a trait, but does not exhibit the trait themselves. They have one copy of the dominant allele and one copy of the recessive allele. This means that carriers can pass on the recessive allele to their offspring, who may then express the trait if they inherit another recessive allele from the other parent.
To determine the correct answer, let's break down the options and understand what each allele combination implies:
A. One recessive and one dominant allele for a trait:
This combination suggests that the person expresses the dominant trait but carries the recessive allele. In this case, the person is not considered a carrier because they themselves exhibit the dominant trait.
B. Two recessive alleles for a trait:
This combination indicates that the person expresses the recessive trait. This person is not a carrier because both of their alleles contribute to the expressed trait.
C. Two dominant alleles for a trait:
This combination implies that the person expresses the dominant trait. Similar to option A, the person is not considered a carrier because they fully exhibit the dominant trait.
D. More than two alleles for a trait:
This option is not applicable in this context because individuals typically have only two alleles for a specific trait (one from each parent). So, this is not the correct answer.
Based on the analysis above, the correct answer is B. Two recessive alleles for a trait. In this case, the person expresses the recessive trait while carrying two copies of the recessive allele. This individual is considered a carrier because they can pass on the recessive allele to their offspring without showing the trait themselves.