Imagine that a couple is planning to have children. The male is heterozygous for tongue rolling and homozygous dominant for unat

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Imagine that a couple is planning to have children. The male is heterozygous for tongue rolling and homozygous dominant for unat

tached earlobes. The female is homozygous recessive for tongue rolling and heterozygous for unattached earlobes. The couple is curious about the possibility and probability of their offspring inheriting these traits. The ability to roll ones tongue is dominant (R) over the “non-rolling” condition (r.) Unattached earlobes (U) are dominant over attached earlobes (u) Complete a Punnett square for this cross and record the probabilities for genotypes and phenotypes of the offspring as ratios.

Biology

1 answer:

inysia [2.3K] · Answer 1 · 2026-04-02T12:58:21+03:00

Response:

F1 generation: RrUu, rrUU, rrUu, RrUU

25%: 25%: 25%: 25%

Ratios

genotype: 1: 1: 1: 1...(derived from punnet square)
phenotype: 1: 1

Clarification:

Punnett squares serve as a visual tool to determine the traits of hybrid offspring produced through genetic crosses. The genotypes and phenotypes of the parents are typically well understood, conforming to typical Mendelian ratios and inheritance patterns.

The study of Mendelian genetics emphasizes the origin or transmission of traits. Traits are contained within gametes produced individually and may exhibit dominance, such that one trait can obscure the expression of another.

These principles are referred to as the Law of Segregation, Independent assortment, and Dominance, respectively.

In this instance... Assumptions:

Unattached lobes are dominant

The ability to roll the tongue is dominant
Parent generation or P generation:

Gametes:

R → rolling trait (R), non-rolling trait (r)

U → unattached trait (U), attached trait (u)

P generation: RUrU× rUru

rolling, unattached × non-rolling, unattached

F1 generation: RrUu, rrUU, rrUu, RrUU

25%: 25%: 25%: 25%

Ratios

genotype: 1: 1: 1: 1...(from punnet square)
phenotype: 1: 1

Half of the offspring will have unattached lobes and the ability to roll their tongues, while the other half will have unattached lobes but will be unable to roll their tongues...

Each punnet cross is attached below