Dihybrid Inheritance and Chi Square Analysis
In this experiment, we crossed male mutant fruit flies, which were homozygous and recessive for
both of the phenotypes with wild females that were homozygous dominant for both of the
phenotypes. The male fruit flies had an ebony body and vestigial wings, bbnn, and the females had a
normal body with normal wings, BBNN.
BN BN BN BN
bn BbNn BbNn BbNn BbNn
bn BbNn BbNn BbNn BbNn
bn BbNn BbNn BbNn BbNn
bn BbNn BbNn BbNn BbNn
BN Bn bN bn
BN BBNN BBNn BbNN BbNn
Bn BBNn BBnn BbNn Bbnn
bN BbNN BbNn bbNN bbNn
bn BbNn Bbnn bbNn bbnn
Ratio 9:3:3:1
Results
Phenotype Numbers Counted
Normal body Normal Wing 209
Normal body Vestigial wing 81
Ebony body, normal wing 90
Ebony Body Vestigial Wing 35
Alternative Hypothesis: There will be a difference between observed and expected results. Our
results did not follow the rations.
Null Hypothesis: There is no difference between observed and expected. Our results did follow the
Mendelian ratios