Question

Among a species of butterflies, the color blue (B) is a dominant trait. Yellow color (b) is a recessive trait. If a pure blue butterfly (BB) mates with a pure yellow (bb), what will the offspring look like?
A) They will all be blue.
B) They will all be yellow.
C) Half will be blue and half will be yellow.
D) About 75% will be blue and 25% will be yellow.

Answer 1

Answer: The correct answer is- A) They will all be blue.

As per the information given in the question, blue color (B) is dominant trait in butterflies over the yellow color (b), which is a recessive trait.

As we know that dominant trait always masks the expression of recessive trait.

The possible genotypes for blue color butterfly are- Bb (heterozygous dominant) and BB (homozygous dominant) whereas for yellow color butterfly is bb (homozygous recessive).

Genotypes of the parents are - BB (which will produce gametes, B and B) and bb (which will produce gametes, b and b).

When these parents are crossed, their offspring will have the genotype Bb (heterozygous dominant).

Thus, they will all be blue.

Answer 2

A) They will all be blue.