Final answer:
To determine the expected proportion of offspring with the dominant phenotype at all four loci in a tetrahybrid cross, we can use genotypic proportions. We calculate the probability of offspring being homozygous dominant or heterozygous at each locus and multiply those probabilities together using the product rule.
Step-by-step explanation:
To determine the expected proportion of offspring with the dominant phenotype at all four loci in a tetrahybrid cross, we can use genotypic proportions. We need to calculate the probability of offspring being homozygous dominant at each locus or heterozygous at each locus, and then multiply those probabilities together using the product rule. For example, if the probability of a homozygous dominant genotype at one locus is 1/4 and the probability of a heterozygous genotype at another locus is 1/2, the overall probability of both of these genotypes occurring is (1/4) x (1/2) = 1/8. The same calculation can be done for each locus, and the final probability of offspring having the dominant phenotype at all four loci will be the product of the individual probabilities.