Complete dominance = When the dominant allele completely masks the recessive allele in a heterozygous individual, so only the dominant trait is expressed.
Incomplete dominance = When neither allele is completely dominant, and the heterozygous phenotype is a blend of the two homozygous phenotypes.
Codominance = When both alleles in a heterozygous individual are fully and separately expressed, resulting in a phenotype that shows both traits simultaneously.
Hybrid = An organism that is heterozygous for a particular trait (has two different alleles).
Purebred Line = An organism that is homozygous for a trait (has two identical alleles), and will breed true for that trait.
1. a. Red snapdragon genotype: RR
b. Pink snapdragon genotype: RW
c. White snapdragon genotype: WW
2. a. pink x pink
Punnett Square:
| R | W
---|----|---
R | RR | RW
W | RW | WW
Genotypic Ratio: 1 : 2 : 1 (RR : RW : WW)
Phenotypic Ratio: 1 : 2 : 1 (Red : Pink : White)
b. red x white
Punnett Square:
| R | R
---|----|---
W | RW | RW
W | RW | RW
Genotypic Ratio: 0 : 4 : 0 (RR : RW : WW) or simply 4 RW
Phenotypic Ratio: 0 : 4 : 0 (Red : Pink : White) or simply 4 Pink
c. pink x white
Punnett Square:
| R | W
---|----|---
W | RW | WW
W | RW | WW
Genotypic Ratio: 0 : 2 : 2 (RR : RW : WW)
Phenotypic Ratio: 0 : 2 : 2 (Red : Pink : White)
Parent Tip: Review the logic above to help your child master the concept of codominance punnett square worksheet.
