Question

In corn, purple kernel color is dominant over yellow; and starchy kernels are dominant over sweet. A plant heterozygous for both color and texture is crossed with one that is yellow and sweet. Using appropriate symbols diagram the cross, identifying genotypes and phenotypes of parents and offspring

Answer 1

In a cross between a heterozygous corn plant (PpSs) for kernel color and texture and a yellow sweet corn plant (ppss), a Punnett square predicts a 1:1:1:1 genotype ratio and corresponding phenotypes of Purple Starchy, Purple Sweet, Yellow Starchy, and Yellow Sweet.

Step-by-step explanation:

To understand the cross between a corn plant that is heterozygous for both kernel color and texture (PpSs) and a plant with yellow and sweet kernels (ppss), we use Punnett squares to predict the genotypes and phenotypes of the offspring. The dominant traits are purple kernel color (P) and starchy texture (S), while the recessive traits are yellow color (p) and sweet texture (s).

The genotypes of the parents are PpSs (heterozygous purple starchy) and ppss (homozygous yellow sweet). To diagram the cross, we set up a Punnett square with the alleles from the heterozygous parent along the top and the alleles from the homozygous recessive parent down the side. After filling in the Punnett square, we find the following:

• Genotype PpSs: 1/4 of offspring - Phenotype: Purple, Starchy
• Genotype Ppss: 1/4 of offspring - Phenotype: Purple, Sweet
• Genotype ppSs: 1/4 of offspring - Phenotype: Yellow, Starchy
• Genotype ppss: 1/4 of offspring - Phenotype: Yellow, Sweet

The square results in a 1:1:1:1 ratio for the four possible genotypes and corresponding phenotypes among the offspring.