Asked by Celeste Yanez on Jun 04, 2024
Verified
Unattached earlobes (EE or Ee) are dominant over attached earlobes (ee) . A couple has unattached earlobes. Both notice that one of their parents on both sides have attached earlobes (ee) . Therefore, they correctly assume that they are carriers for attached earlobes (Ee) . If the couple proceeds to have four children, then
A) they can be certain that three will be heterozygous and one homozygous recessive.
B) if the first three are heterozygous, the fourth must be homozygous recessive.
C) the children must repeat the grandparents' genotype (Ee) .
D) all children must have unattached earlobes since both parents possess the dominant gene for it.
E) two heterozygous, one homozygous dominant, and one homozygous recessive is a likely outcome, but all genotype ratios are possible.
Unattached Earlobes
A genetic trait where the earlobes hang free and are not connected to the side of the head.
Homozygous Recessive
An individual is homozygous recessive when they have two identical recessive alleles for a particular gene, potentially expressing a recessive trait.
Heterozygous
Having two different alleles of a particular gene or genes, resulting in genetic variation for a specific trait.
- Invoke Mendelian genetics principles to anticipate the results in monohybrid and dihybrid cross experiments.
- Assess the ratios of phenotypic and genotypic outcomes in descendants produced by distinct methods of genetic crossing.
Verified Answer
ZK
Zybrea KnightJun 08, 2024
Final Answer :
E
Explanation :
Since both parents are carriers (Ee) for attached earlobes, there is a 25% chance that each child will inherit the recessive allele (ee) and have attached earlobes, and a 75% chance that they will inherit at least one dominant allele (E or e) and have unattached earlobes. The possible genotypes for the children are therefore: EE (25%), Ee (50%), and ee (25%). This translates to two heterozygous (Ee), one homozygous dominant (EE), and one homozygous recessive (ee) as likely outcomes, but all genotype ratios are technically possible.
Learning Objectives
- Invoke Mendelian genetics principles to anticipate the results in monohybrid and dihybrid cross experiments.
- Assess the ratios of phenotypic and genotypic outcomes in descendants produced by distinct methods of genetic crossing.