Mendel's Monohybrid Crosses: Results and Ratios
| Parental Traits | Numbers in F2 |
| Dominant in F1 | Recessive in F1 | Dominant | Recessive | Total | Ratio |
| Spherical | Wrinkled seeds | 5,474 | 1,850 | 7,324 | 2.96 : 1 |
| Yellow | Green seeds | 6,022 | 2,001 | 8,023 | 3.01 : 1 |
| Purple | White flowers | 705 | 224 | 929 | 3.15 : 1 |
| Inflated | Constricted pods | 882 | 299 | 1,181 | 2.95 : 1 |
| Green | Yellow pods | 428 | 152 | 580 | 2.82 : 1 |
| Axial | Terminal flowers | 651 | 207 | 858 | 3.14 : 1 |
| Tall | Dwarf stems | 787 | 277 | 1,064 | 2.84 : 1 |
Observed Results vs. Expected Results
| Parental Traits | Numbers in F2 |
| Dominant in F1 | Recessive in F1 | Dominant | Recessive | Total |  |
| Observed | Expected | Observed | Expected | |
|---|
| Spherical | Wrinkled seeds | 5,474 | 5,493 | 1,850 | 1,831 | 7,324 | 0.26 |
| Yellow | Green seeds | 6,022 | 6,017 | 2,001 | 2,006 | 8,023 | 0.02 |
| Purple | White flowers | 705 | 697 | 224 | 232 | 929 | 0.37 |
| Inflated | Constricted pods | 882 | 886 | 299 | 295 | 1,181 | 0.07 |
| Green | Yellow pods | 428 | 435 | 152 | 145 | 580 | 0.45 |
| Axial | Terminal flowers | 651 | 643 | 207 | 215 | 858 | 0.40 |
| Tall | Dwarf stems | 787 | 798 | 277 | 266 | 1,064 | 0.61 |
A value of 3.84 or greater would be signficant at the 5% level of confidence.
Mendel's Monohybrid Cross Results: F3 Patterns
According to Mendel's hypothesis, the F2 progeny showing the dominant phenotype are composed of two genotypic classes: homozygotes and heterozygotes in a ratio of 1 : 2. In order to test the prediction of a specific ratio of the two genotypic classes in the dominant phenotype of the F2, Mendel allowed some of the F2 to self-fertilize and produce an F3 generation. Within the F3 generation, he asked how many were pure breeding (homozygous) and how many showed segregation for the two original parental characters (heterozygous). The results are given below:
| Parental Character | F3 Plants Which Show |
| Pure-breeding | Segregation | Ratio | |
|---|
|
| Seed shape | 193 | 372 | 1 : 1.93 | 0.17 |
| Seed color | 166 | 353 | 1 : 2.13 | 0.42 |
| Flower color | 36 | 64 | 1 : 1.787 | 0.32 |
| Pod shape | 29 | 71 | 1 : 2.45 | 0.85 |
| Pod color | 40 | 60 | 1 : 1.50 | 2.00 |
| Flower position | 33 | 67 | 1 : 2.03 | 0.01 |
| Stem height | 28 | 72 | 1 : 2.57 | 1.28 |
A value of 3.84 or greater would be signficant at the 5% level of confidence.
This document maintained by Robert J. Huskey.
Last update on October 20, 1999.
