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Read the section on Hardy-Weinberg in your textbook (ch. 23.2) then solve the fo

ID: 201906 • Letter: R

Question

Read the section on Hardy-Weinberg in your textbook (ch. 23.2) then solve the following problem. Show your work! 3. A snap dragon is a type of flower that has incomplete color dominance. White snap dragons are homozygous for the allele coding for the color white; whereas red snap dragons are homozygous for the allele coding for the color red. A snap dragon that has one allele coding for white and one allele coding for red will be pink. Out of a sample of 100 snap dragons, 65% have the allele for the color red CR and 35% have the allele for coding for the color white CW. Under the assumptions for the Hardy-Weinberg principle, how many flowers will be red, white, and pink? The equation for predicting genotype frequencies (Hardy-Weinberg equation) is: p2 + 2pq + q2 = 1 p2 is the amount expected for genotype CRCR 2pq q2 is the amount expected for genotype CWCW Your textbook also provides guidance on how to calculate these values by setting-up your problem in a similar way to a Punnett square. Use the square below if it helps you find the answer.

Explanation / Answer

Given information,

Frequency of red allele, p = 65% = 0.65

Frequency of white allele, q = 35% = 0.35

According to HW equilibrium,

p2 + 2pq + q2 = 1

p+q = 1

Frequency of red flowered plants, p2 = 0.65 X 0.65

= 0.4225

= 42.25%

Frequency of white flowered plants, q2 = 0.35 X 0.35

= 0.1225

= 12.25%

Frequency of pink flowered plants, 2pq = 2 X 0.65 X 0.35

= 0.455

= 45.5%

p2 + 2pq + q2 = 1

42.25 + 12.25 + 45.5 = 100 = 1