If you did not know whether brown or yellow alleles were dominant in corn, how could you tell with reasonable certainty? If you used a punette square to find out which one is dominant, how would you know which letters to use for each parent to figure out the F1 generation?

Question

If you did not know whether brown or yellow alleles were dominant in corn, how could you tell with reasonable certainty? If you used a punette square to find out which one is dominant, how would you know which letters to use for each parent to figure out the F1 generation?

Answer 1

If the two genes are in the same allele, both parents are heterozygous, and the genes are either dominant or recessive, then about 25% of F1 generation will show recessive phenotype and 75% will show the dominant phenotype.

Homozygous = BB or YY

Heterozygous = BY

Once you find out which is dominant and which is recessive, use a lower case letter to indicate the recessive gene.