Question

Mendelian ratios are modified in crosses involving autotetraploids. Assume that one plant expresses the dominant trait green seeds and is homozygous (wwww). This plant is crossed to one with white seeds that is also homozygous (wwww). If at least two dominant alleles are required to produce green seeds (one or no dominant alleles produces white seeds), predict the F2 phenotypic ratios of such a cross. Assume that chromosomes pair during meiosis and independent assortment occurs.

Answer 1

In a cross involving autotetraploids, the F2 phenotypic ratios can be predicted based on Mendelian genetics principles. The predicted F2 phenotypic ratios for a cross between a plant with homozygous dominant green seeds and a plant with homozygous recessive white seeds are 1:7, 2:4:1.

Step-by-step explanation:

In a cross involving autotetraploids, such as the one described in the question, the F2 phenotypic ratios can be predicted based on Mendelian genetics principles. In this case, one plant is homozygous for the dominant trait green seeds (wwww) and is crossed with a plant that is also homozygous for white seeds (wwww). Since at least two dominant alleles are required for green seeds, the F2 phenotypic ratios can be predicted as follows:

• 1:7 of plants with green seeds (homozygous dominant)
• 2:4 of plants with green seeds (homozygous dominant) : white seeds (homozygous recessive)
• 1:7 of plants with white seeds (homozygous recessive)