• ♂ parent appears as T
  • ♀ parent appears as S


  • S offspring = 0.
  • T offspring = 37.

Bean plants can have short stalks or tall stalks. Assume that these effects are caused by a single gene in which one allele is completely dominant to the other. S refers to short stalks and T refers to tall stalks. Note that these letters are different; only one can be used directly as a gene symbol.

Decide upon a gene symbol based on the recessive phenotype (there is not enough information in this question for you to know which is mutant). Define the alleles with a single letter, capitalizing the dominant allele and use lower-case for the recessive.

Assume the ratios fit a standard 1:1, 1:0, or 3:1 ratio and that chance does not make one ratio look like another (i.e. a 3:1 doesn't accidentally fit a 1:1).

If there is not enough information in the data provided to determine which allele is dominant, click the bottom button for more info.

Dominant symbol
Recessive symbol