In a population of butterflies, blue wing color is determined by a dominant allele (B), green by a recessive allele (G). The frequency of B is 0.3. If the population is in H-W equilibrium, how many green winged butterflies do you expect in a population of 500?

a. 255
b. 245
c. 490
d. 0.70
e. 350
f. 150

b. 245

Explanation:

The Formula proposed by Hardy- Weinberg Equilibrium is:

p + q = 1

p² + 2pq + q² = 1

p is the frequency of the dominant allele.

q  is the frequency of the recessive allele.

p² is the frequency of individuals with the homozygous dominant genotype.

2pq is the frequency of individuals with the heterozygous genotype.

q² is the frequency of individuals with the homozygous recessive genotype.

From the question, we were told that;

blue wing color is determined by a dominant allele (B) = p = 0.3

Then we are tasked with finding the frequency of recessive  green allele (G). = q ???(unknown)

From above equation; we have :

p + q = 1

Since p = 0.3, we can find q

q can now be ;

q = 1 - p

q = 1 - 0.3

q = 0.7

If q = 0.7;

then q² = (0.7)²

q²  = 0.49

We can now multiply the frequency of individuals by the total population in order to get the number of individal with the given genotype were are tasked to find;

So, we have:

= 0.49 × 500

= 245

∴ From the total population; there are  245 green winged butterflies in population of 500 butterflies.

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