Anonymous

# Frequency in Population?

Pink flowers are Homozygous dominant and White flowers are homozygous recessive. In 2009 white flowers comprised 8% of a population. What is the frequency of the homozygous dominant and heterozygous in this population?

Relevance

You would want to use the Hardy-Weinberg Law for calculating this.

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

where

p^2=frequency of AA (homozygous dominant) in population

2pq=frequency of Aa (heterozygous) in population

q^2=frequency of aa (homozygous recessive) in population

Since q^2 is the aa in population (the white flowers) we know that q^2=8%, or q^2=0.08.

This would make q=0.2828.

You then have p^2+2p(0.2828)+(0.2828)^2=1

p^2+0.5656p+0.08=1

p^2+0.5656p-0.92=0

This leaves you with a quadratic, which when solved gives you p=0.7172

(I cheated on this step and used a quadratic equation solving app)

Now to solve for p^2 and 2pq

p^2=0.7172^2=0.514, or 51.4%

2pq=2*0.7172*0.2828=0.406 or 40.6%

So, you have

=51.4% AA (Homozygous dominant, pink flowers)

=40.6% Aa (Heterozygous, pink flowers)

To check, you can make sure that, with the 8% Homozygous recessive, this adds up to 100%

....

Or you could completely cheat and use this Hardy-Weinberg Calculator.

http://www.changbioscience.com/genetics/hardy.html