An S1S2 ×S1S2 mating is performed. If the phenotypic ratio of the progeny is 3:1, then... (Justify your answer) A) one allele is dominant and the other is recessive. B) neither allele is dominant. C) the S1 allele is dominant to the S2 allele. D) the S2 allele is dominant to the S1 allele. E) the relationship between the alleles cannot be determined
An S1S2 ×S1S2 mating is performed. If the
(Justify your answer)
A) one allele is dominant and the other is recessive.
B) neither allele is dominant.
C) the S1 allele is dominant to the S2 allele.
D) the S2 allele is dominant to the S1 allele.
E) the relationship between the alleles cannot be determined
In the given case, each parent has one dominant allele and one recessive allele making both the parents heterozygotes. Mating two heterozygous individuals result in a phenotype with a fraction of 3:1, where three progenies have a dominant phenotype and one has a recessive phenotype. These are phenotypic ratios rather than genotypic ratios, and the cross follows the rules of Mendelian genetics. The above cross does not specify which allele is dominant or recessive. Thus we can conclude one allele is dominant and the other is recessive.
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