If a Punnett square shows two dominant traits and one recessive trait, what is the most likely phenotype ratio?

If a Punnett square shows two dominant traits and one recessive trait, what is the most likely phenotype ratio?

• A. 1:1
• B. 2:1
• C. 3:1
• D. 4:1

Answer: (C)

In a Punnett square involving two dominant traits and one recessive trait, each trait typically has two alleles: a dominant allele and a recessive allele. When you cross two organisms that are heterozygous for both dominant traits (for example, AaBb x AaBb), the resulting phenotypic ratio can be determined through the use of a Punnett square. For two traits, the genotypic ratio from such a cross would be expecting 9:3:3:1 when considering the combinations of dominant and recessive alleles. This translates into phenotypes where 9 out of 16 possible combinations express the dominant phenotypes (the two dominant traits), while 3 represent one trait being recessive, and another trait being dominant, and 1 represents both traits being recessive. Therefore, when focusing solely on the dominant traits in this scenario, you would expect to see a majority of the offspring displaying the dominant phenotypes compared to the recessive one, leading to that recognized ratio of 3:1 for the two dominant traits versus the one recessive trait. This explains why the phenotype ratio of 3:1 is the most logical conclusion from a cross displaying two dominant traits alongside one recessive trait.

In a Punnett square involving two dominant traits and one recessive trait, each trait typically has two alleles: a dominant allele and a recessive allele. When you cross two organisms that are heterozygous for both dominant traits (for example, AaBb x AaBb), the resulting phenotypic ratio can be determined through the use of a Punnett square.

For two traits, the genotypic ratio from such a cross would be expecting 9:3:3:1 when considering the combinations of dominant and recessive alleles. This translates into phenotypes where 9 out of 16 possible combinations express the dominant phenotypes (the two dominant traits), while 3 represent one trait being recessive, and another trait being dominant, and 1 represents both traits being recessive.

Therefore, when focusing solely on the dominant traits in this scenario, you would expect to see a majority of the offspring displaying the dominant phenotypes compared to the recessive one, leading to that recognized ratio of 3:1 for the two dominant traits versus the one recessive trait. This explains why the phenotype ratio of 3:1 is the most logical conclusion from a cross displaying two dominant traits alongside one recessive trait.