Question

Question 8 2 pts Earlobe attachment in humans exhibits Mendelian inheritance. Individuals with free earlobes are homozygous dominant (FF) or heterozygous (Ff), while those with attached earlobes are homozygous recessive (ff). A child has attached earlobes, but both parents have free earlobes. What are possible genotypes of the parents? OFF:Ff OFF; FF Off:ff Ffff

Answer 1

The right option is option (a) Ff ; Ff

Explanation:-

As the question states that the attached earlobe gene is recessive, so if anyone have attached earlobe then they are homozygous for attached earlobe, i.e, their genotype is ff.

Now according to the question, the parents of the kid have free earlobes meaning that they have atleast obe F allele as the allele is dominant and shows phenotype even in heterozygous condition.

When two parent with Dominant phenotype have a kid with Recessive phenotype, it means that they are both heterozygous because offsprings get one allele from each parent and in case of recessive traits they need 2 copies of the recessive allele one from each parent. That makes the parent heterozygous.

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I have upload an image to show a punette square for two heterozygous parent in which the ratio of offsppring is 1:2:1 with 1 kid being recessive homozygous out of the 4 kids.