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Biology · Inheritance · Monohybrid cross
Monohybrid cross simulator
A single gene with two alleles: T (tall, dominant) and t (short, recessive). Pick the genotype of each parent. The Punnett square shows the predicted gamete combinations. Run the cross 100 or 1000 times to see how observed offspring compare with expectation.
Parent 1
Tall (heterozygous)
Parent 2
Tall (heterozygous)
n = 0
Genotypes
| Genotype | obs | obs % | exp % |
|---|---|---|---|
| TT | 0 | — | 25.0 |
| Tt | 0 | — | 50.0 |
| tt | 0 | — | 25.0 |
Phenotypes
| Phenotype | obs | exp |
|---|---|---|
| Tall | 0 | 0 |
| Short | 0 | 0 |
Exam-style questions
1. Two heterozygous tall plants (Tt × Tt) are crossed. What is the EXPECTED phenotype ratio?
2. A test cross is used to find the genotype of a tall plant. What is the SECOND parent?
3. If a test cross (Unknown × tt) produces ONLY tall offspring, the unknown parent's genotype is:
4. Why do real-world offspring numbers vary around the expected ratio (e.g. 297 : 103 instead of exactly 300 : 100 out of 400)?