In humans, free earlobes (F) are dominant to attached earlobes (f). A female and make with free earlobes has a offspring that is homozygous for attached earlobes. What are the genotypes of the parents?
A) Ff x Ff
B) ff x ff
C) ff x FF
D) FF x FF
A
correct
To determine the genotypes of the parents, we need to analyze the offspring's genotype and use the information about earlobe characteristics being dominant or recessive.
Given that free earlobes (F) are dominant to attached earlobes (f), and the offspring is homozygous for attached earlobes, we can conclude that both parents must carry at least one recessive allele for attached earlobes.
Let's analyze the options provided:
A) Ff x Ff: This option suggests that both parents have one dominant (free earlobe) allele and one recessive (attached earlobe) allele, which is not consistent with having an offspring that is homozygous for attached earlobes.
B) ff x ff: This option suggests that both parents have two recessive (attached earlobe) alleles, which is consistent with having an offspring that is homozygous for attached earlobes.
C) ff x FF: This option suggests that one parent has two recessive (attached earlobe) alleles, and the other parent has two dominant (free earlobe) alleles, which is not consistent with having an offspring that is homozygous for attached earlobes.
D) FF x FF: This option suggests that both parents have two dominant (free earlobe) alleles, which is not consistent with having an offspring that is homozygous for attached earlobes.
Based on the analysis, the correct answer is B) ff x ff. Both parents must have the genotype ff to produce an offspring that is homozygous for attached earlobes.