Help with genotypes?

Question

I not only need answers but PLEASE explain how you got them so I can understand and do it on my own next time.


1. What are the possible genotypes of a person who has a widow's peak?

2. What are the possible genotypes of a person who can roll his tongue?


3 What is the genotype of someone without a widow's peak?

4.What is the genotype of someone who cannot roll her tongue?

5. What is the genotype of a person who is heterozygous for both traits?

Answer 1

A widow's peak and rolling your tongue are one gene traits and both are dominant. Therefore, a person who has a widow's peak has the possibility of having Aa or AA (A=widow's peak, a= no widows peak). Same for rolling your tongue, either Aa or AA (A=rolling your tongue, a=not rolling your tongue).

Since both these traits are dominant, in order to not have them show up, the person must be homozygous for the recessive trait (aa, where a=not having a widows peak or not rolling your tongue).

A person who is heterozygous for both traits will have the dominant phenotype show up, that is, they will have a widows peak and be able to roll their tongue.

Answer 2

Well first of all you need to know if a widow's peak is a dominant or recessive gene. I searched quickly in google and found that a widow's peak is a dominant trait.

W = dominant gene for widow's peak
w = recessive, no widow's peak

So in order to have a widow's peak a person must have a dominant gene, so the genotypes are WW or Ww.
If a person has ww there will not be a widow's peak.

Tongue rolling is the same thing,
R = dominant gene for tongue roll
r = recessive gene, no tongue roll

So a person with genes RR or Rr will be able to roll their tongue.
If a person has rr they will not be able to roll their tongue.

A person that is heterozygous (hetero meaning the opposite) will have alleles that look like this : Ww and Rr, meaning they carry both the dominante and recessive gene for each trait. Since they carry the dominant gene, the person will display the characteristics of both a widow's peak and the ability to roll the tongue.

Answer 3

let the all the dominant alleles to be R
and all the recessive alleles to be r

1. widow's peak is recessive so the person has to be homozygous recessive and would have a genotype of, lets say rr.

2. . so anyone one who can tongue roll would have either RR or Rr. get it?

3. as mentioned above u can get widow's peak only when u are homozygous recessive, hence some one without widow's peak would have either RR or Rr

4. as mentioned above again. tongue rolling is dominant, if u cannot roll ur tongue, u must be homozygous recessive and hence rr.

5. do you mean Rr?