Inheritance in Maize (Indian Corn)
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Renee Allen Louis Wirth Experimental
4959 South Blackstone
Chicago, Illinois (606l5)
To calculate the phenotypic ratios for some monohybrid and dihybrid crosses.
To determine the genotypes of parents from the phenotypic ratios of their
mutant corn ears
pencil and paper
Commercially available corn represent crosses between various parental
genotypes. Results of a cross between pure-breeding purple kernel corn and
pure-breeding yellow kernel corn produces offspring which are all purple
(demonstrating dominance). A cross between two of these offspring produce 3/4
purple and 1/4 yellow kernel corn. These are the commercially available ears.
Obtain ears of corn representing offspring of crosses from various mutant and
wild type plants from a biological supply company. Divide the class into groups
of two or three. Give each group an ear of corn. Place a pin at one end of a
row of kernels to mark your starting row. Using a pencil to point to the
kernels, one partner should indicate the phenotype of each kernel while the
other partner keeps a tally.
Each ear of corn is labeled with a code.
1. For each ear of corn, calculate and record the ratio of the phenotypes.
Divide the number of purple by the number of yellow. Also, divide the number
of starchy by the number of sweet.
2. From the data, determine the genotypes of the parents in each cross.
3. How do the actual offspring phenotype ratios compare with the expected