Question

1. A pea plant heterozygous for yellow, smooth seeds is crossed with a plant with green, wrinkled seeds. What is the genotypic and phenotypic ratio demonstrated in the F1 generation? 2. Let's expand what we did in the previous question. A pea plant heterozygous for yellow, smooth seeds and purple flowers is crossed with a plant with green, wrinkled seeds and homozygous dominant for purple flowers. What is the genotypic and ratio of offspring demonstrated in the F1 generation?

Answer 1

In both cases, because one or both parents are heterozygous, the resulting F1 generation will feature a variety of phenotypes. The ratios obtained depend on the genetic traits of the parents and functions of dominant and recessive alleles. The phenotypic and genotypic ratios can be determined using Punnett squares.

Step-by-step explanation:

The questions pertain to Mendelian genetics, specifically dihybrid crosses. In Mendel's pea plants, yellow and smooth traits are dominant while green and wrinkled traits are recessive.

1. The cross between a heterozygous yellow, smooth seed pea plant (YySs) and a homozygous recessive green, wrinkled seed pea plant (yyss) results in an F1 generation exhibiting a phenotypic ratio of 1:1:1:1 (yellow, smooth : yellow, wrinkled : green, smooth : green, wrinkled) and a genotypic ratio of 1:1:1:1 (YySs: Yyss: yySs: yyss).
2. When the problem is expanded to include flower color, the purple color is dominant. Therefore, a cross between a heterozygous yellow, smooth seed and heterozygous purple flowers (YySsPp) and a homozygous recessive green, wrinkled seed and homozygous dominant purple flowers (yyssPP) would result in a phenotypic ratio of 1:1:1:1:1:1:1:1 (yellow, smooth, purple : yellow, smooth, white : yellow, wrinkled, purple : yellow, wrinkled, white : green, smooth, purple : green, smooth, white : green, wrinkled, purple : green, wrinkled, white.) and a genotypic ratio of 1:1:1:1:1:1:1:1 (YySsPp : YySspp : YyssPp : Yysspp : yySsPp : yySspp : yyssPp : yysspp) These calculations require basic understanding of Mendelian genetics and Punnett squares.

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