1. Mendallian Genetics Words to know:
Probability: a number that describes how likely it is for something to happen
Pure bred: offspring that have the same alleles
Hybrid: offspring has two different alleles for each trait
Genotype: genetic make up; allele combination
Phenotype: physical appearance

2. T. Trimpe 2008 http://sciencespot.net/
Punnett Practice #1
T. Trimpe

3. 1. Predict the offspring from a cross between a purebred tall pea plant and a hybrid tall plant. Use T for tall and t for short.
(a) Give the genotypes Purebred Tall = ____ Hybrid Tall = ____
(b) Create a Punnett square to determine the genotypes for the offspring.
(c) What is the probability that a plant would be tall? _______ %
(d) What is the probability that a plant would be short? _______ %
2. Predict the offspring from a cross between two hybrid tall pea plants.
(a) Give the genotype for a hybrid tall plant. ______
(c) What is the probability that a plant would be tall? _____ %
(d) What is the probability that a plant would be short? _____ %
(e) If you were to plant 100 seeds from this cross, how many would you expect to be tall?

4. 1. Predict the offspring from a cross between a purebred tall pea plant and a hybrid tall plant. Use T for tall and t for short.
(a) Give the genotypes Purebred Tall = ____ Hybrid Tall = ____
(b) Create a Punnett square to determine the genotypes for the offspring.
(c) What is the probability that a plant would be tall?
(d) What is the probability that a plant would be short? TT Tt T t TT Tt
100% 0%

5. 2. Predict the offspring from a cross between two hybrid tall pea plants.
(a) Give the genotype for a hybrid tall plant. ______
(b) Create a Punnett square to determine the genotypes for the offspring.
(c) What is the probability that a plant would be tall?
(d) What is the probability that a plant would be short?
(e) If you were to plant 100 seeds from this cross, how many would you expect to be tall? Tt T t TT Tt tt
75%
25%
75% of 100 = 75 plants

6. T. Trimpe 2008 http://sciencespot.net/
Punnett Practice #2
T. Trimpe

7. 1. Predict the offspring from a cross between a purebred pea plant with purple flowers and a pea plant with white flowers. Use P for purple and p for white.
(a) Give the genotypes Purebred Purple = ____ White = ____
(b) Create a Punnett square to determine the genotypes for the offspring.
(c) What is the probability that a plant would have purple flowers? _______ %
(d) What is the probability that a plant would have white flowers? _______ %
2. If you crossed two hybrid plants with purple flowers and planted 200 of the seeds, how many would you expect to have with white flowers. Create a Punnett square to support your answer.

8. 1. Predict the offspring from a cross between a purebred pea plant with purple flowers and a pea plant with white flowers. Use P for purple and p for white.
(a) Give the genotypes Purebred Purple = ____ White = ____
(b) Create a Punnett square to determine the genotypes for the offspring.
(c) What is the probability that a plant would have purple flowers?
(d) What is the probability that a plant would have white flowers? PP pp P p Pp
100% 0%

9. 2. If you crossed two hybrid plants with purple flowers and planted 200 of the seeds, how many would you expect to have with white flowers. Create a Punnett square to support your answer. P p PP Pp pp
You would expect to see white flowers on 25% of the plants, which would be 50 plants.

10. T. Trimpe 2008 http://sciencespot.net/
Punnett Practice #3
T. Trimpe

11. Some people have dimples, while others do not
Some people have dimples, while others do not. The presence of dimples is a dominant trait (D), while not having dimples is recessive (d).
(1) Susie has dimples, but her husband, Tom, does not. Their first child has his father's phenotype. What are the genotypes of the mother, father, and child?
Mother’s Genotype: _______
Father’s Genotype: _______
Son’s Genotype: _______
(2) What is the probability that a second child won’t have dimples? Create a Punnett square to support your answer.

12. Some people have dimples, while others do not
Some people have dimples, while others do not. The presence of dimples is a dominant trait (D), while not having dimples is recessive (d).
(1) Susie has dimples, but her husband, Tom, does not. Their first child has his father's phenotype. What are the genotypes of the mother, father, and child?
Mother’s Genotype: _______
Father’s Genotype: _______
Son’s Genotype: _______
(2) What is the probability that a second child won’t have dimples? Create a Punnett square to support your answer. Dd dd D d Dd dd
There would be a 50% probability that the second child would not have dimples.