Edexcel IGCSE Biology · Spec 3.23-3.25
Monohybrid Crosses
How to complete monohybrid genetic crosses using Punnett squares and predict the offspring ratios.
Biology revision video
Monohybrid Crosses
Prefer to watch on YouTube? Open this video on YouTube.
Spec 3.23-3.25
What you need to know
- Set out the alleles for a monohybrid cross
- Use a Punnett square to find possible offspring genotypes
- Calculate phenotype ratios and probabilities
Active recall
Quick check
Answer each question before opening the answer.
What is a monohybrid cross?
A genetic cross that follows the inheritance of a single gene.
What offspring ratio do you expect from crossing two heterozygotes (Tt × Tt)?
3 : 1 (dominant phenotype : recessive phenotype).
Biology video companion
Keep your notes and exam practice together
The free Biology workbook follows every video in specification order.