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Name: Period:

Video Review: Two Factor Crosses & Independent Assortment:

1. Mendel discovered many things about the characteristics of pea plants including the qualities of

the peas themselves. What two things did Mendel discover?

a. ________________________________________________________________________

b. ________________________________________________________________________

2. Complete the Punnett squares for heterozygous round (round is dominant):

What is the genotype: _____________________ and what is the phenotype: ________________

3. Complete the Punnett square for heterozygous yellow (yellow is dominant):

What is the genotype: ____________________ and what is the phenotype: ________________

4. What patterns might be seen when observing traits at the same time. If you have a pea that is

pure breed round and yellow, what is the genotype? ___________________________________

5. If you have a pea that is pure breed wrinkled and green, what is the genotype? ______________

6. If Mendel cross pollinates these plants, remember each parent gives half of their genes.

a. What would parent RRYY give to the offspring? ________________

b. What would parent rryy give to the offspring? _________________

7. What is the result of the offspring F1 generation? _____________________

8. Now the F1 generation will self-pollinate. What will be the resulting F2 generation Rr x Yy?

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9. What is the following results for the F2 generation?

a. Genotypes: __________________________________________________________

b. Phenotypes: _________________________________________________________

10. To explain these results, Mendel proposed the principle of independent assortment.

a. What is the definition of independent assortment:

____________________________________________________________________

b. Given an example of independent assortment:

____________________________________________________________________

11. What are the possible genotypes for RrYy:

a. ______________________________________

b. ______________________________________

c. ______________________________________

d. ______________________________________

12. What are the possible phenotype for RrYy:

a. RY: ___________________________________

b. Ry: ___________________________________

c. rY: ___________________________________

d. ry: ___________________________________

13. A Punnett can predict how these genotypes and phenotypes can occur. These dihybrid crosses

show 4 different phenotypes that can arise. Fill in the missing parts to the dihybrid cross

Punnett square below:

RY Ry rY ry

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Using the Punnett square, list the genotypes:

Using the Punnett square, list the phenotypes:

They should be the same as #11 & #12 above.

14. Chromosomes will line up and separate independently of each other. For example look at the

independent assortment for brown hair, red hair and brown eyes, blue eyes. Fill-in the

phenotypes below:

___________________ __________________

___________________ __________________

15. List the three steps to building a dihybrid Punnett squares:

a. ______________________________________________________________________

b. ______________________________________________________________________

c. ______________________________________________________________________

16. Practice: Guinea pigs Black (B) is dominant to Brown (b) & short hair (S) is dominant to Long (s).

Cross two Heterozygous Black and short guinea pigs.

a. Step 1: What is the genotype for the two parents? ______________________________

b. Step 2: What are the gametes (Independent Assortment)? Fill-in the blanks below:

__________ x __________

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17. Practice the SMILE Format, in the space below, (similar to FOIL for algebra), using BbSs:

18. Now set up your Punnett square:

Using the Punnett square, list the genotypes:

Using the Punnett square, list the phenotypes:

19. Fill in the blanks for the final results of phenotypes:

9: ____________________ 3: _________________ 3: _______________ 1: _______________ 20. List the 3 reasons when this 9:3:3:1 ratio occurs:

a. __________________________________________ b. __________________________________________ c. __________________________________________

Video Review: Amoeba Sisters Dihybrid Crosses:

1. Define the prefix mono- for monohybrid cross: 2. Define a dihybrid cross: 3. Define the prefix di- for dihybrid cross: 4. Where does the cat “Moo” like to hang out in the house? 5. For practice, cats that do like sinks, what is the dominant allele? 6. For practice, cats that do not like sinks, what is the recessive allele? 7. For practice, cats that have hair, what is the dominant allele? 8. For practice, cats what do not have hair, what is the recessive allele? 9. What is the genotype for a cat having heterozygous having hair and heterozygous liking sinks?

___________________________________________ 10. What is the genotype for a cat having no hair and not liking sinks?

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___________________________________________ 11. Define gametes? 12. What are the gametes for the parents?

___________ or ____________ ____________ or ______________

13. Define Mendel’s Law of Segregation: 14. Summarize Step 1: 15. Summarize Step 2:

FOIL the first parent: HhSs

FOIL the second parent: hhss

21. Now set up your Punnett square:

Using the Punnett square, list the genotypes:

Using the Punnett square, list the phenotypes:

22. Looking at your results, what is the phenotype of a kitten having hair and likes sinks?

23. What is the ratio of the following:

a. Hairy and likes sinks:

b. Hairy and does not like sinks:

c. Hairless and does like sinks:

d. Hairless and does not like sinks:

24. In this case, what are the genotype to phenotype ratios?

AMOEBA SISTERS: VIDEO RECAP DIHYBRID CROSSES (MENDELIAN)

Amoeba Sisters Video Recap: Dihybrid Crosses (Mendelian Inheritance)

Vocabulary practice! You probably have had enough of cats with our video. On to peas! In pea plants, yellow peas (coded for

by a dominant allele Y) are dominant to green peas (requiring two recessive alleles y). Round peas (coded for by a dominant

allele R) are dominant to wrinkly peas (requiring two recessive r alleles). These are actual pea plant traits, by the way!

For the following, please write in the genotype or phenotype. Some are filled in for you.

7. An allele is a form of a gene. In a dihybrid cross HhSs x hhss, how

many alleles does a kitten inherit from the mother? _______

8. How many alleles does a kitten inherit from the father? _______.

9. Gametes, which are sex cells, carry the alleles. Why must a gamete carry one allele (represented by a letter) from each

gene? Meaning, why can’t a gamete carry an “hh” instead of an “hs” or an “Hh” instead of a “HS?”

The Dihybrid Problem Solve

Read the beginning part about pea plants again. Bernard really likes growing peas in his garden, but the peas he likes are

green. He also likes them to have a wrinkled texture, because he thinks they look much more interesting that way. Please

work out a RrYy x RrYy (heterozygous cross) on the back of this sheet or on another paper while showing all work.

10. After showing your work to use as support, what is the chance that Bernard will have pea plant offspring that match the

phenotype he is looking for (green, wrinkled)? _______________________

11. What is the phenotype ratio of this heterozygous cross?

________(yellow, round): __________(yellow, wrinkled): ___________(green, round) : ___________(green, wrinkled)

12. If Bernard did not receive any pea plants that were green and wrinkled in actuality, would you know for sure that the

parent genotypes were incorrect? Why or why not? _________________________________________________________

____________________________________________________________________________________________________

DIHYBRID CROSS Name ___________________________

Phenotypic ratios - How many, out of 16 are:

Black, Short Black, Long White, Short White, Long________________ ______________________ ______________________ _____________________

A cross (or mating) between two organisms where two genes are studied is called a DIHYBRID cross.

The genes are located on separate chromosomes, so the traits themselves are unrelated.

Fill out the genotypes of each of the offspring to determine how many of each type of offspring are produced.

BB = blackBb = blackbb = white

LL = short hairLl = short hairll = long hair

How many of the offspring are:

Black, Short ______

Black, Long ______

White, Short ______

White, Long ______

How many of the offspring are:

Black, Short ______

Black, Long ______

White, Short ______

White, Long ______