Dihybrid Cross Outcome Visualizer
Run the Dihybrid Cross Outcome Visualizer MicroSim Fullscreen
About This MicroSim
This MicroSim lets students explore dihybrid crosses using two classic pea plant traits: seed shape (Round vs. Wrinkled, alleles R/r) and seed color (Yellow vs. Green, alleles Y/y). A 4x4 Punnett square shows all 16 offspring genotypes alongside a bar chart displaying phenotype counts, reinforcing the connection between the grid method and the expected 9:3:3:1 ratio.
How to Use
- Select parent genotypes using the dropdown menus for each locus (e.g., Rr x Rr, YY x Yy)
- Read the Punnett square to see all 16 offspring combinations
- Toggle between genotype and phenotype views using the button
- Click a bar in the chart to highlight all matching cells in the Punnett square
- Hover over bars to see exact counts and percentages
- Observe the ratio in the summary line below the chart
Lesson Plan
Grade Level
9-12 (college placement Biology)
Duration
10-15 minutes
Prerequisites
- Understanding of dominant and recessive alleles
- Familiarity with monohybrid crosses and Punnett squares
- Knowledge of Mendel's Law of Segregation
Activities
- Exploration (5 min): Set both parents to heterozygous (RrYy x RrYy) and observe the classic 9:3:3:1 ratio. Toggle between genotype and phenotype views.
- Guided Practice (5 min): Change one parent to homozygous dominant (RRYY) and predict the outcome before looking. Try other combinations and compare ratios.
- Assessment (5 min): Given a specific ratio outcome, work backward to determine what the parent genotypes must have been.
Assessment
- Can the student predict the phenotypic ratio before changing parent genotypes?
- Can the student explain why the 9:3:3:1 ratio only appears with two heterozygous parents?
- Can the student identify which genotypes produce each phenotype category?