Question

In fruit flies, brown bodies are dominant to black bodies. Cross two heterozygous fruit flies. Determine

the phenotypic and genotypic ratios. Then determine how many fruit flies, if 200 are born, will have
black bodies.

Answer 1

Step-by-step explanation:

In this case, we can use Punnett square to determine the genotypic and phenotypic ratios of the offspring:

B b

B BB (brown) Bb (brown)

b Bb (brown) bb (black)

So, when we cross two heterozygous fruit flies (Bb x Bb), we get the following genotypic ratios:

25% BB (brown)

50% Bb (brown)

25% bb (black)

And the following phenotypic ratios:

75% brown bodies

25% black bodies

Therefore, if 200 fruit flies are born, we can estimate that 25% of them will have black bodies, which is:

0.25 x 200 = 50 fruit flies