A fly has two alleles for the color of its eyes. The green allele is recessive and is represented by [tex]q[/tex]. The blue allele is dominant and is represented by [tex]p[/tex]. If 20 out of 100 organisms are green, what is [tex]q[/tex]?

Homozygous dominant + Heterozygous + Homozygous recessive = 1

A. 0.89
B. 0.55
C. 0.45
D. 0.80



Answer :

Let's solve this step-by-step:

1. Given Information:
- There are a total of 100 organisms.
- 20 of these organisms have green eyes.

2. Understanding the Green Allele:
- The green allele is recessive, denoted by [tex]\( q \)[/tex].
- This means organisms with green eyes have two recessive alleles ([tex]\( q^2 \)[/tex]).
- The frequency of organisms with green eyes in the population is therefore the fraction of green-eyed organisms: [tex]\(\frac{20}{100} = 0.2 \)[/tex].

3. Finding the Frequency of the Recessive Allele, [tex]\( q \)[/tex]:
- We have [tex]\[ q^2 = 0.2 \][/tex].
- To find [tex]\( q \)[/tex], take the square root of both sides: [tex]\[ q = \sqrt{0.2} \][/tex].

4. Calculating the Square Root:
- Using the square root operation, we obtain: [tex]\[ q = 0.4472135954999579 \][/tex].

5. Choosing the Closest Answer:
- Among the options provided:
- A. 0.89
- B. 0.55
- C. 0.45
- D. 0.80

- The closest value to the calculated [tex]\( q \)[/tex] (0.4472135954999579) is option C: 0.45.

Thus, the correct answer is C. 0.45.