Which of the following phenotypic results are expected from a dihybrid cross?
Correct answer: B. 9:3:3:1 ratio
- A. 1:1:1:1 ratio
- B. 9:3:3:1 ratio
- C. All dominant for both traits
- D. All recessive for both traits
Explanation
Both the product rule and the Punnett Square approaches showed that a 9:3:3:1 phenotypic ratio is expected among the progeny of a dihybrid cross such as Mendel's RrYy × RrYy. In making these calculations, we assumed that: both loci assort independently; one allele at each locus is completely dominant; and.
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About Inheritance
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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