Final answer:
The rule of portability is useful in calculating the risk that certain individuals will inherit a particular genotype. It involves multiplying the individual probabilities of each event occurring alone. For example, in a cross between an individual with two dominant alleles (AA) and an individual with two recessive alleles for the same trait (aa), all of the offspring of the second generation would have the genotype Aa with a 100 percent probability of expressing the phenotype of the dominant allele.
Step-by-step explanation:
In genetics, the rule of portability is useful in calculating the risk that certain individuals will inherit a particular genotype. The rule of portability states that the probability of inheriting a particular genotype can be calculated by multiplying the individual probabilities of each event occurring alone.
For example, consider a cross between an individual with two dominant alleles (AA) and an individual with two recessive alleles for the same trait (aa). The parental gametes from the dominant individual would be A, and the parental gametes from the recessive individual would be a. All of the offspring of the second generation, inheriting one allele from each parent, would have the genotype Aa. The probability of expressing the phenotype of the dominant allele would be 4 out of 4, or 100 percent.