Punnet square indicates that_of F2 progeny would have been homozygous round_ heterozygous round and_wrinkled, respectively:
Correct answer: A. 1/4, 2/4, 1/4
- A. 1/4, 2/4, 1/4
- B. 2/4, 1/4, 1/4
- C. 1/4, 1/4, 2/4
- D. 2/4, 1/4, 2/4
Explanation
In a monohybrid cross involving a dominant and recessive allele (e.g., round and wrinkled), the Punnett square reflects a 3:1 phenotypic ratio in the F2 generation. Specifically, the genotypic ratio is 1/4 RR (homozygous round), 1/2 Rr (heterozygous round), and 1/4 rr (wrinkled). This pattern arises due to the segregation of alleles, consistent with Mendel's laws of inheritance. Options B, C, and D suggest ratios that deviate from this expected pattern, incorrectly representing the distributions of genotypes.
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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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