1. Punnett Square Practice
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2. STOP! Before you go any farther, save this file!
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Save the file in the folder with your Student ID number
When you have done this, continue on.

3. Instructions Today you will learn about Punnett Squares.
If you are not already viewing this in presentation mode, please press the F5 key to start viewing it in presentation mode so you can see how to do the presentation.

4. Instructions – please read
A green pea plant (GG) is being crossed with a green pea plant (Gg) yellow is the
recessive color.
Parent 2
Parent 1
Parent 1 has a Genotype of GG and a Phenotype of Green.
Parent 2 has a Genotype of Gg and a Phenotype of Green.
This means G is dominant and will make a green phenotype if there is GG or Gg.
That means g is recessive and will make a yellow phenotype if there is gg.
We’re now going to predict what their children would be like.

5. G G G g Instructions – please watch
To predict what a parent will produce, we use a Punnett Square, named after the man who invented it.
A green pea plant (GG) is being crossed with a green pea plant (Gg) yellow is the recessive color.
See how the GG from Parent 1 separates into each space.
Step 1 – Put the parents on the outside of the Punnett Square G G G
Notice how the Gg from Parent 2 separates into each space. g

6. Instructions – please watch
To predict what a parent will produce, we use a Punnett Square, named after the man who invented it.
A green pea plant (GG) is being crossed with a green pea plant (Gg) yellow is the recessive color.
Step 1 – Put the parents on the outside of the Punnett Square
Step 2 – Take one allele from each parent and combine them in each box. G G G G G G G
Your Punnett Square is complete! g G g G G

7. Instructions – Please Watch
A green pea plant (GG) is being crossed with a green pea plant (Gg) yellow is the
recessive color.
Only one box is Gg, which is still dominant, but it is heterozygous dominant. 1 out of 4 boxes means it is 25%.
Step 3 – Figure out the probability of each Genotype and Phenotype.
This would be GG
3 out of the 4 boxes are GG, so that equals 75%
The Phenotype is Green because it is GG G G
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
75%
Green
Dominant Heterozygous
25%
Recessive homozygous 0%
Yellow G G G G G g G g G G

8. Now You Try! Be careful with capitalization!
You will fill in the Punnett Square on each slide.
You will also figure out what percent of the boxes are:
Dominant Homozygous (2 capital letters: GG)
Dominant Heterozygous (1 capital, 1 lowercase: Gg)
Recessive Homozygous (2 lowercase letters: gg)
Remember…
4 out of 4 = 100%
3 out of 4 = 75%
2out of 4 = 50%
1 out of 4 = 25%
Be careful with capitalization!

9. A green pea plant (Gg) is crossed with a yellow pea plant (gg).
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

10. A tall plant (TT) is crossed with a tall plant (Tt).
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

11. A tall plant (Tt) is crossed with a short plant (tt).
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

12. A red flower (Rr) is crossed with a white flower (rr).
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

13. A white flower (rr) is crossed with a white flower (rr).
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

14. A black chicken (BB) is crossed with a black chicken (BB).
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

15. Now for Something New
Now we will take this one step further. You will have to figure out what the parents’ alleles are based on the description.
Remember…
Homozygous means two of the same
Heterozygous means two different
You can have dominant homozygous (2 capital letters: BB)
You can have recessive homozygous (2 lowercase letters: bb)
You can have dominant heterozygous (1 capital letter, 1 lowercase letter: Bb)

16. A homozygous dominant brown mouse is crossed with a heterozygous brown mouse (tan is the recessive color).
Genotype
Phenotype
Parent 1
Parent 2
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

17. Two heterozygous white (brown fur is recessive) rabbits are crossed.
Genotype
Phenotype
Parent 1
Parent 2
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

18. Two heterozygous red flowers (white flowers are recessive) are crossed.
Genotype
Phenotype
Parent 1
Parent 2
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous

19. A heterozygous white rabbit is crossed with a homozygous black rabbit.
Genotype
Phenotype
Parent 1
Parent 2
Calculate the percent outcome for Genotype and describe the phenotype for each combination.
Genetic Combination
Genotype
Phenotype
Dominant Homozygous
Dominant Heterozygous
Recessive homozygous