Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and the Yahoo Answers website is now in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

Anonymous
Anonymous asked in Science & MathematicsBiology · 9 years ago

# 64% of a population is able to taste a chemical called PTC. Tasters are either homozygous dominant or?

64% of a population is able to taste a chemical called PTC. Tasters are either homozygous dominant or heterozygous for the trait. For the parts that follow, show all formulas, calculations and statements:

a) Calculate the percentage of the population that is Unable to taste PTC ?

b) Calculate the percentage of the population that is heterozygous for the trait?

c) Calculate the percentage of the population that has the recessive allele ? (Hint: heterozygous + homozygous recessive.)

### 2 Answers

Relevance
• Anonymous
9 years ago
Favorite Answer

Using the Hardy-Weinberg equations:

f(non tasters) = q^2 = 0.36 a), so q = 0.6 and p=0.4

b) f(heterozygotes) = 2pq = 0.6*0.4*2 = 0.48

c) 0.48 + 0.36 = 0.84 = 84%

• 64% = DD (must carry a dominant allele)

so D = square root of 64% (0.64) is 0.8

d + D = 1 d = recessive

1 - 0.8 = 0.2 carry recessive allele (d)

So dd (people that cant taste it as they must carry a dominant allele, and so no dominant allele = cant taste it) is 0.2 squared = 0.04 (4%) homozygous recessive. That is the answer to A.

Heterozygous.

You must use the equation:

q^2 + p^2 + 2pq = 1

2pq is for the heterozygous.

You know that the d (recessive) is 0.2 and D (dominant) is 0.8

So heterozygous is 2pq so, (0.2 x 0.8) x 2 = 0.32 = 32% (heterozygous). This is the answer to B.

You know this is correct because it must add up to 1 (or 100%). 32% is heterozygous, 4% is homozygous recessive and 64% is homozygous dominant = 100%

Wow this took LONG! Points please!

Still have questions? Get your answers by asking now.