In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for exampl
e, W- means the individual has either the genotype WW or Ww. In summer squash, genotypes W- G- and W- gg are white, ww G- are yellow, and ww gg are green. W and G show independent assortment. What is the ratio of white : yellow : green among progeny of the cross Ww Gg × Ww Gg?
According to Mendel's principles, a dihybrid cross between two heterozygous summer squash parents (WwGg X WwGg) should yield offsprings, 12 with white, 3 with yellow and 1 with green color phenotype. The classic Mendelian phenotypic ratio for dihybrid cross is 9:3:3:1. In this case, genotypes W- G- and W- gg produce white color phenotype. This is because we have 12: 3: 1 phenotypic ratio in which the alleles of two different genes assort independently into gametes.
<em>Dihybrid cross for heterozygous summer squash:</em>
photosynthesis takes carbon dioxide from the air, and water from the soil to make oxygen, which is then released back into the air, and the glucose is stored and used as energy within the plant
