Homework Help

How would I complete the punnett square and describe the genotype ratio and the...

user profile pic

islnds | Valedictorian

Posted June 18, 2013 at 10:43 PM via web

dislike 0 like

How would I complete the punnett square and describe the genotype ratio and the phenotype ratio of the offspring?

Brown hair(B) is dominant to blonde hair(b) and curly hair(H) is dominant to straight hair(h). A woman who is hybrid for both brown hair and curly hair marries to a man who has blond straight hair.

1 Answer | Add Yours

Top Answer

user profile pic

rahelb | Elementary School Teacher | (Level 2) Adjunct Educator

Posted June 18, 2013 at 11:36 PM (Answer #1)

dislike 0 like

The Punnett square would look like the attached image and results in a total of 16 possibile outcomes.

The mother would be identified as BbHh because she has brown hair that is also curly, but it also says that she is a hybrid for both traits, which means that she carries both the dominant and the recessive gene for both traits. The father is identified as bbhh because he has blonde hair that is strait and both characteristics are recessive, so to display those traits he could only carry the recessive genes of the characteristic.

The genotype describes the actual gentic make-up of the offspring and this Punnett square yields the following results: BbHh, Bbhh, bbHh, and bbhh. All four possibilities have a 4 in 16, or 1 in 4, chance of occurring.

As for phenotypes, which give the actual physical outcome, we have the following possibilities:

1. BbHh = brown, curly hair

2. Bbhh = brown, straight hair

3. bbHh = blonde, straight hair

4. bbhh = blonde, straight hair

Each of these have an equal chance of occurring, 4 in 16, or 1 in 4.

Images:
This image has been Flagged as inappropriate Click to unflag
Image (1 of 1)

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes