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In humans, brown hair is dominant over blonde hair. Also in humans, detached earlobes are dominant over attached earlobes. If a male that is heterozygous for both traits has children with a female that is heterozygous for both traits, their offspring’s phenotypes would be represented by which of the following ratios: *


A)4:4:4:4



B)9:3:3:1



C)16:0



D)3:1

Respuesta :

Answer:

B) 9:3:3:1

Explanation:

A punnet square can be described as a diagram in which the outcomes of a cross between parent carrying certain traits can be studied.

A cross in which only one trait is studied will be termed as a monohybrid cross. For example, making a cross for just hair colour.

A cross in which two traits are being studied at a time is termed as a dihybrid cross. For example, studying the hair color and the pattern of earlobes in a single punnet square.

The pnnet square for the scenario discussed in the question can be made as follws:

              BE               Be                bE                 be

BE     BBEE         BBEe             BbEE             BbEe

Be     BBEe         BBee             BbEe             Bbee

bE     BbEE         BbEe              bbEE             bbEe

be     BbEe        Bbee               bbEe               bbee

The results of the cross show that :

  • 9/16 show probability for having brown hair and detached earlobes.
  • 3/16 have the probability of having brown hair and attached earlobes.
  • 3/16 have the probability of having blonde hair and detached earlobes.
  • 1/16 have the probability of having blonde hair and attached earlobes.