Final answer:
2) 25% The probability of the offspring being bb when both parents are homozygous recessive bb is 100%, as each parent can only contribute a recessive b allele.
Step-by-step explanation:
The question about genetics pertains to predicting the genotypes of offspring given the genotypes of the parents. In this scenario, two parents with genotype bb are crossed. Since both parents are homozygous recessive, all their gametes will carry the b allele.
When we use a Punnett square to illustrate the cross of bb x bb, each parent can only contribute a b allele, because that is the only allele they have. Therefore, all the offspring from this cross will be bb, showing the recessive phenotype. The probability that any given offspring will be bb is therefore 100%.
The probability of the offspring being bb is 25%.
When a bb individual mates with another bb individual, both parents contribute a recessive allele b to each offspring. The possible genotypes of the offspring are bb, Bb, Bb, and BB. Out of these four possibilities, only one genotype is bb. Therefore, the probability of the offspring being bb is 1 out of 4, or 25%.