Question

In feathered serpents, two genes control the overall serpentine look: feathering (feathers, F, are dominant to no feathers, f) and color (blue body, B, is dominant to white body, b). You testcross a dihybrid blue, feathered serpents and obtain 12 blue, feathered babies; 2 blue, featherless babies; 14 white, featherless babies, and 1 white, feathered baby. Which babies are recombinants?
a. blue and featherless
b. all blue babies
c. all white babies
d. blue and feathered

Answer 1

Answer:

a. blue and featherless

Explanation:

• Feathers (F) are dominant to no feathers (f)
• Blue body (B) is dominant to white body (b)

If we testcross a dihybrid, we are crossing a homozygous recessive individual with a heterozygous individual.

Recombination is a rare event in meiosis, so the more abundant offspring are always the parentals, and the less abundant offspring are the recombinant ones.

In this case, bf/bf and BF/bf are the parentals and Bf/bf and bF/bf are the recombinants.

The option a. Blue and featherless (Bf/bf) offspring are the recombinant babies.