- The worksheet focuses on dihybrid crosses, which involve two traits (pea shape and pea color) with dominant and recessive alleles.
- Alleles: R = round (dominant), r = wrinkled (recessive); Y = yellow (dominant), y = green (recessive).
- Gametes for a heterozygous parent (RrYy) are determined using the FOIL method: RY, Ry, rY, ry.
- A sample cross RrYy × rryy is shown, resulting in offspring genotypes: RrYy, Rryy, rrYy, rryy.
- For the cross rr yy × Rr yy:
- Parent 1 (rryy) produces only ry gametes.
- Parent 2 (Rryy) produces Ry and ry gametes.
- Offspring: 50% Rryy (round green), 50% rryy (wrinkled green).
- Round green: 50%, Wrinkled green: 50%.
- For the cross rr yy × RR Yy:
- Parent 1 (rryy) produces only ry gametes.
- Parent 2 (RRYy) produces RY and Ry gametes.
- Offspring: 50% RrYy (round yellow), 50% Rryy (round green).
- Round green: 50%, Wrinkled green: 0%.
- For the cross RR Yy × Rr Yy:
- Parent 1 (RRYy) produces RY and Ry gametes.
- Parent 2 (RrYy) produces RY, Ry, rY, ry gametes.
- Offspring ratios: 3/8 round yellow, 3/8 round green, 1/8 wrinkled yellow, 1/8 wrinkled green.
- Round green: 3/8, Wrinkled green: 1/8.
Parent Tip: Review the logic above to help your child master the concept of dihybrid crosses worksheet.
