On the planet Seltaeb, there is a rare recessive condition known as Hofner Bassis (BB) in the Blue Meanies, a race whose genomes are identical to that of humans. Individuals with this condition can be clearly identified, as they are very musically gifted. The two alleles at this locus are B (the trait allele) and b. If both parents are known to be carriers for the recessive gene, what is the probability that they will have an unaffected child? A. 0B. 0.75C. 0.10D. 0.50E. 0.25

Question

Carissa

Biology

4 May, 10:15

On the planet Seltaeb, there is a rare recessive condition known as Hofner Bassis (BB) in the Blue Meanies, a race whose genomes are identical to that of humans. Individuals with this condition can be clearly identified, as they are very musically gifted. The two alleles at this locus are B (the trait allele) and b. If both parents are known to be carriers for the recessive gene, what is the probability that they will have an unaffected child? A. 0B. 0.75C. 0.10D. 0.50E. 0.25

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Answers (1)

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Copper · Answer 1

The correct option is B. 0.75

Explanation:

The punnet square for this cross can be shown as follows:

B b

B BB Bb

b Bb bb

As the trait is a recessive disorder, both the alleles of the gene should be BB for the trait to occur. According to the punnet square, there is 25% chance (0.25) that the organism will have the recessive condition. As the punnet square shows, there is a 75% (0.75) chance that the offsprings will be unaffected. However, 50% will be carriers.