Hardy Weinberg Question from Bootcamp

[dentalduck15]

Here is the question followed by the solution. Im not getting it and I know its easy. Help please. A population of fish is in Hardy-Weinberg equilibrium. Red-colored scales are a dominant trait and blue-colored scales are a recessive trait. In the population, 36% of the fish display red-colored scales. What percent of the population in the next generation is expected to be homozygous dominant?

The Hardy-Weinberg equation is p + q = 1, and p2 + 2pq + q2 = 1, where:

p2 = homozygous dominant
2pq = heterozygous
q2 = homozygous recessive

The general strategy for all Hardy-Weinberg problems is that we have to find the individual values of p and q, and then use those values to solve for what the question is asking. We’re given that 36% of the population shows a dominant phenotype, and this number includes both homozygous dominant and heterozygous dominant phenotypes. If 36% show the dominant phenotype, then 64% of the population shows the recessive phenotype. In accordance to the above equations:

q2 = 0.64
q = 0.80
p = 0.20
p2 = (0.20)2 = 0.04 X 100 = 4%

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[ekam]

Red Color is a dominant trait

According to my understanding, the percentages given are p^2 or q^2 values.
P^2 = 36

To approach such questions, always start with recessive allele.

percent for recessive allele is 100-36 = 64

So q^2 = .64
sort of .64 is .8

So now you have your q value. To find p value use the equation p+q=1
p = 1- .8 = .2

In question you are asked for % homozygous dominant, i.e. p^2 value

.2^2 = 4

 

[dentalduck15]

thanks.

 

[dentalduck15]

hey, if p^2=36,

Red Color is a dominant trait

According to my understanding, the percentages given are p^2 or q^2 values.
P^2 = 36

To approach such questions, always start with recessive allele.

percent for recessive allele is 100-36 = 64

So q^2 = .64
sort of .64 is .8

So now you have your q value. To find p value use the equation p+q=1
p = 1- .8 = .2

In question you are asked for % homozygous dominant, i.e. p^2 value

.2^2 = 4

Hey, if p^2 =36, why cant I take the sqrt to fint p?

 

[GGNUPE12]

Thanks for posting this I was having trouble with that question as well!

 

[ekam]

Sorry. My bad. I messed up 😱
p^2 will not be equal to 36

because both homozygous dominant and heterozygous will show the same phenotypic trait i.e. red in this question.
p^2 +2pq = 36

 

[BobbyBeavis]

Hi guys. I didn't read all of the posts in this thread, but just wanted to inform you that I had 3 questions on my DAT I took today involving Hardy-Weinberg! So I would make sure to know it. A few practice problems will leave you with the concepts down, and it isn't too hard. I had no clue after reading Cliffs AP about it, but doing a few problems on Bootcamp/Destroyer helped me understand it.

All DATs are not created equal, though!

 

[dentalduck15]

Hi guys. I didn't read all of the posts in this thread, but just wanted to inform you that I had 3 questions on my DAT I took today involving Hardy-Weinberg! So I would make sure to know it. A few practice problems will leave you with the concepts down, and it isn't too hard. I had no clue after reading Cliffs AP about it, but doing a few problems on Bootcamp/Destroyer helped me understand it.

All DATs are not created equal, though!

hey, how was your DAT? Is Bootcamp better or Destroyer. I have 15 days left until my exam, still dont feel good.

 

[BobbyBeavis]

hey, how was your DAT? Is Bootcamp better or Destroyer. I have 15 days left until my exam, still dont feel good.

15 days? You can do both!

Knowing my weak areas were Bio/PAT, I should have worked on those, but I am still loving my other high scores 🙂

I never felt good about my test, just knew I had studied hard and told myself I would give it my all!

 

[dentalduck15]

15 days? You can do both!

Knowing my weak areas were Bio/PAT, I should have worked on those, but I am still loving my other high scores 🙂

I never felt good about my test, just knew I had studied hard and told myself I would give it my all!

you are awsome. Im not giving up. im working on both right now. ochem is killing me since I took it like more than a year ago. I feel the best about Bio and PAT, thats funny.