B b

B BB Bb
b Bb bb

Brown rabbits have the genotype BB or Bb. White rabbits have the genotype bb. If two brown rabbits, with the genotypes seen in the Punnett square above, have baby rabbits, what is the probability that the baby rabbits will also be brown?
Responses
A 25%25%
B 50%50%
C 75%75%
D 100%

1 answer

To determine the probability that the baby rabbits from two brown rabbits (with genotypes shown in the Punnett square) will be brown, we can analyze the genotypes that the parents can pass on.

The two brown rabbits in the Punnett square are:

  • One parent is BB (homozygous dominant).
  • The other parent is Bb (heterozygous).

From the Punnett square:

          B      B
        -----------------
      B |   BB   |   BB   |
        -----------------
      b |   Bb   |   Bb   |
        -----------------

From this, the possible genotypes of the offspring are:

  • BB (2 possibilities)
  • Bb (2 possibilities)

So the resulting offspring could be either BB or Bb, both of which correspond to brown rabbits.

To calculate the probability:

  • Total outcomes = 4 (2 BB + 2 Bb)
  • Total brown outcomes = 4 (all BB and Bb are brown)

The probability that a baby rabbit will be brown is thus calculated as follows:

  • Probability = Number of brown rabbits / Total outcomes = 4/4 = 1.

So the percentage probability is 100%.

The correct response is D: 100%.