Question

A study found that children with light-colored eyes are likely to have parents with light-colored eyes. On this basis, can we say anything about whether the light eye color trait is dominant or recessive? Why or why not?

Answer 1

Dominant trait:

1. Dominance is the phenomenon in genetics where one version of a gene on chromosome masks or overrides the action of another variant of the same gene on the other copy of the chromosome.
2. The first variant is known as dominant, whereas the second is known as recessive.

Recessive trait:

A trait that is expressed only when the genotype is homozygous; a trait that is concealed by other inherited qualities yet persists in a population among heterozygous genotypes.

Light-colored eyes genotype:

1. The law of dominance states that when two homozygous organisms are crossed with a single pair of contrasting traits, the trait that is expressed in the first generation is called dominant, and the trait that is not expressed is called recessive.
2. Eye color is another polygenic feature influenced by numerous genes.
3. The phenotype manifested is the result of the interaction of dominant alleles. When both offspring and parents have bright eyes, there must be no dominant genes or one of two may be present.
4. It is impossible to tell whether a trait is dominant or recessive without knowing its genetics.
5. As a result, at least three generations are required to determine whether a characteristic is dominant or recessive.
6. If it was heterozygous, the next generation would inherit a darker eye color gene (3:1).
7. If it was homozygous, it could only be recessive because no pure lines of dominant genes were acquired.
8. So, while just two generations of data are provided, the genotype of the parents and three generations of data are required to confirm.