A monohybrid cross occurs when the parents differ in one (phenotypic) trait only.
Below I will show the steps and the right way to do a monohybrid cross or any cross at all (you can be asked this in the SCT or exam).
Mendel crossed plants with Round seeds with those with Wrinkled seeds. The round trait is the dominant one and the wrinkled is recessive.
- When writing the genotypes, always use the same letter. Use the capital letter for the dominant and the small letter for the recessive.
- When writing the gametes, always write them in circles (we will see the reason for this in a bit)
Parental Phenotype: Round×Wrinkled
Parental Genotype: RR×rr
Parental Gametes: ⓇⓇ×ⓡⓡ