1. Dihybrid Cross Notes
Looking at 2 traits

2. Steps to Solve a Dihybrid Cross
In race horses, black hair (B) and a trotting gait (G) are dominant traits. Recessive traits are chestnut hair (b) and a pacing gait (g). Determine the possible offspring from a cross between two heterozygous black trotters.
Step 1: Determine the letter for each trait.
B = black hair
b = chestnut hair
G = trotting gait
g = pacing gait

3. Step 2: Determine the genotypes for both parents.
Determine the possible offspring from a cross between two heterozygous black trotters.
BbGg X BbGg

4. Step 3: Set up the Punnett Square
Remember FOIL from Algebra (First, Outside, Inside, Last). BbGg X BbGg BG Bg bG bg BG Bg bG bg

5. Step 4: Fill in the Punnett Square
Begin by filling in the B’s and then go back and fill in the G’s. BG Bg bG bg BG Bg bG bg
BBGG
BBGg
BbGG
BbGg
BBgg
Bbgg
bbGG
bbGg
bbgg