Mark D. answered • 11/26/19
High School Biology Teacher
The decorative corn that you see as part of decorations for fall and Thanksgiving is a classic example of Mendelian genetics. The kernels come in two colors, 'yellow" and "blue/purple," The blue phenotype is caused by the presence of the pigment aleurone, like many pigment genes this is dominant over the base "yellow" pigment. A cross between an entirely blue and an entirely yellow will reveal the genotype of the blue parent. If 100% of the kernels in the next generation are blue the blue parent was homozygous (two copies of the dominant gene) if the offspring are 50% blue and 50% yellow then the blue parent was heterozygous, having a 50% chance of passing the dominant or the recessive allele to a given kernel in an ear.
If two blue parents are crossed their genotypes are revealed by whether any yellow kernels appear in the next generation both parents were heterozygous. The classic ratio would be 75 blue seeds and 25 yellow out of 100.
