1. Defined: Crossing of two traits 16 possible outcomes
Dihybrid
Punnett
Squares
Defined: Crossing of two traits
16 possible outcomes
Use the “FOIL” method from math
F = First
O = Outside
I = Inside
L = Last
Tips:
Place capital letters first
2) Group the same letters together

2. RY Ry ry RY RrYy RrYY RRYY RRYy Ry Rryy RRYy RRyy RrYy rY RrYY RrYy
Cross two heterozygous dominant Round, Yellow seeds with each other.
R r Y y x R r Y y
Key:
R = Round Y = yellow
r = wrinkled y = green RY Ry rY ry RY
RrYy
RrYY
RRYY
RRYy Ry
Rryy
RRYy
RRyy
RrYy rY
RrYY
RrYy
rrYY
rrYy
RrYy ry
Rryy
rrYy
rryy

3. R = Round Y = Yellow 1 RRYY 4 RrYy 1 rrYY 9 Round, Yellow Seeds 2 RRYy
r = wrinkled
Y = Yellow
y = green
List all the Possible Genotypes:
List all the Possible Phenotypes:
1 RRYY
4 RrYy
1 rrYY
9 Round, Yellow Seeds
2 RRYy
1 RRyy
2 rrYy
3 Round, Green Seeds
2 RrYY
2 Rryy
1 rryy
3 Wrinkled, Yellow
1 Wrinkled, Green

4. 1 RRYY 4 RrYy 1 rrYY 9 Round, Yellow Seeds 2 RRYy 1 RRyy 2 rrYy
Genotypes:
Phenotypes:
1 RRYY
4 RrYy
1 rrYY
9 Round, Yellow Seeds
2 RRYy
1 RRyy
2 rrYy
3 Round, Green Seeds
2 RrYY
2 Rryy
1 rryy
3 Wrinkled, Yellow
1 Wrinkled, Green
What is the probability of getting:
Competely homozygous recessive seed?
1/16th
Completely heterozygous plants?
4/16th
Homozygous round seeds?
What is the probability of getting:
Wrinkled, yellow seeds?
3/16th
Green seeds?
4/16th
Three round, yellow seeds?
9/16 x 9/16 x 9/16 =
729/ or %

5. Man: Hemophiliac, Carrier of sickle cell disease Woman: No history of hemophilia, Carrier of sickle cell

6. Man: Hemophiliac, Carrier of sickle cell disease Woman: No history of hemophilia, Carrier of sickle cell

7. Girl with sickle cell disease?
2/16

8. Hemophiliac boy with sickle cell disease?
0/16

9. Girl who carries hemophilia and sickle cell disease?
4/16

10. Child with sickle cell disease?
4/16