DAT Destroyer - Hardy Weinberg Equation

[amalgamgrillz]

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Hello!

Could someone please help me with this DAT destroyer bio question?

144. If 36% of a population has blue eyes, what is the percentage of the recessive allele?
a) 60%
b) 64%
c) 36%
d) 50%
e) 0%

A is the correct answer. From the equation p^2 + 2pq + q^2 =1...

q^2=recessive allele=0.36 ...therefore q=0.6=60% of the population.

However, I was thinking that the recessive PHENOTYPE would be 60%, not the recessive ALLELE. Should the calculation for the recessive allele be:

recessive allele from the heterozygotes ("q" from 2pq) + the homozygote recessive allele (q^2).

Am I thinking about it wrong?

 

[Kahr]

Hello!

Could someone please help me with this DAT destroyer bio question?

144. If 36% of a population has blue eyes, what is the percentage of the recessive allele?
a) 60%
b) 64%
c) 36%
d) 50%
e) 0%

A is the correct answer. From the equation p^2 + 2pq + q^2 =1...

q^2=recessive allele=0.36 ...therefore q=0.6=60% of the population.

However, I was thinking that the recessive PHENOTYPE would be 60%, not the recessive ALLELE. Should the calculation for the recessive allele be:

recessive allele from the heterozygotes ("q" from 2pq) + the homozygote recessive allele (q^2).

Am I thinking about it wrong?

The question tells you that the recessive phenotype is 36% (q^2) right away, so it can't be 60%. They want to know now after giving you the phenotype's percentage (blue eyes being recessive), what the recessive allele's percent is. Since we know that for the recessive phenotype to manifest it must be homozygous for the recessive allele.

So from the equation for each phenotype, we just take the one for a homozygous recessive (q^2 = .36), and find "q" the recessive allele. We only need to know what "q" is, since the equation p + q = 1 accounts for the population's percentage of "dominant p" and "recessive q" alleles.

I don't totally understand your thinking at the bottom, but you don't need 2pq because that simply gives the percentage of heterozygotes, who wouldn't have blue eyes to begin with.

 

[wizi]

Hello!

Could someone please help me with this DAT destroyer bio question?

144. If 36% of a population has blue eyes, what is the percentage of the recessive allele?
a) 60%
b) 64%
c) 36%
d) 50%
e) 0%

A is the correct answer. From the equation p^2 + 2pq + q^2 =1...

q^2=recessive allele=0.36 ...therefore q=0.6=60% of the population.

However, I was thinking that the recessive PHENOTYPE would be 60%, not the recessive ALLELE. Should the calculation for the recessive allele be:

recessive allele from the heterozygotes ("q" from 2pq) + the homozygote recessive allele (q^2).

Am I thinking about it wrong?

Amal,

To be able to understand this question, you have to understand what is the different between phenotype frequency, allele frequency and how they come up with that fomular.

go here: http://www.khanacademy.org/video/hardy-weinberg-principle?playlist=Biology

This video explains it very well. Let us know if you still have questions after watching this video.

 

[invictusx]

Hello!

Could someone please help me with this DAT destroyer bio question?

144. If 36% of a population has blue eyes, what is the percentage of the recessive allele?
a) 60%
b) 64%
c) 36%
d) 50%
e) 0%

A is the correct answer. From the equation p^2 + 2pq + q^2 =1...

q^2=recessive allele=0.36 ...therefore q=0.6=60% of the population.

However, I was thinking that the recessive PHENOTYPE would be 60%, not the recessive ALLELE. Should the calculation for the recessive allele be:

recessive allele from the heterozygotes ("q" from 2pq) + the homozygote recessive allele (q^2).

Am I thinking about it wrong?

Well, first of all, A is correct because...
36% of the population has blue eyes, therefore that's the frequency of recessive homozygotes (phenotype) So, the frequency of alleles would be the square root of .36, which would be .6 aka 60%.

p and q => frequency of alleles
2pq => frequency of heterozygotes (PHENOTYPE)
p^2 and q^2 => frequency of homozygotes (PHENOTYPE)

I think this is how you do it?

 

[amalgamgrillz]

Amal,

To be able to understand this question, you have to understand what is the different between phenotype frequency, allele frequency and how they come up with that fomular.

go here: http://www.khanacademy.org/video/hardy-weinberg-principle?playlist=Biology

This video explains it very well. Let us know if you still have questions after watching this video.

Thanks everyone for your help! I think I have it all cleared up. Great videos by the way! Thanks for showing me that site!

 

[wizi]

Thanks everyone for your help! I think I have it all cleared up. Great videos by the way! Thanks for showing me that site!

Glad I can help. I just went over this section 🙂

 

[Benman44]

Just studied this stuff yesterday! Good luck with everything!! were right here with ya 🙂