“Do you want to build a snowman?” Dihybrid Cross Worksheet

Trait / Dominant Gene / Recessive Gene
Body size / Small (S) / Large (s)
Snow Color / White (W) / Blue (w)
Feet / Snow feet absent (F) / Snow feet present (f)
Nose Style / Long (L) / Stubby (l)

Use the chart to identify the genotype of the following traits:

1.  Heterozygous long nose, large body: ______

2.  Hybrid small body, homozygous white snow body: ______

3.  Snow feet present, stubby nose: ______

Olaf’s best friend, Frosty the (large) Snowman was bragging that he’d found the most adorable snow lady to marry. Frosty loves his (hybrid) small lady’s cute snow feet and wants Olaf to figure out the chances that Frosty can hear the pitter patter of little snow feet running through the forest, even though Frosty doesn’t have any feet of his own (Ff).

Identify the genotypes:

4.  Frosty: large body, no feet: ______

5.  Frosty’s fiancée: small body, feet: ______

6.  Frosty: long nose (hybrid), white body (hybrid) ______

7.  fiancé: long nose (heterozygous), white body (heterozygous) ______

8.  What is the probability that Frosty and his fiancé will have a large baby with snow feet? (Hint: Remember to multiply your fractions)

9.  What is the probability that Frosty and his fiancé will have a small baby with a long nose?

10.  What is the probability that Frosty and his fiancé will have a blue baby with a short nose?

11.  What are their chances of having a white baby with a long nose? (use the Punnett square from #10)

As we know Olaf is hybrid for his long nose and white body color. His wife Olga is blue and was born with a stubby nose. Use this information to answer the following questions.

12.  Give the genotypes for Olaf: ______and Olga: ______

WwLl / Wwll / wwLl / wwll
WwLl / Wwll / wwLl / wwll
WwLl / Wwll / wwLl / wwll
WwLl / Wwll / wwLl / wwll

13.  What are their chances of having a blue snow baby? ______

14.  What are their chances of having a blue long nosed snow baby? ______

15.  What are their chances of having a white snow baby? ______

16.  What are their chances of having a purebred dominant snow baby (both traits)? ______

17.  What’s the phenotypic ratio for the cross above? (label your traits)______

In royals, black hair (H) is dominant to blond hair (h) and being magic free (M) is dominant to having (ice) magic (m). Elsa is considering a marriage proposal from Prince Charming who is magic-free (heterozygous), but pure bred for his beautiful blond hair. Reminder: Elsa is blond and has magic.

18.  What is Prince Charming’s phenotype? ______

19.  Is it possible for Elsa and Charming to have children that resemble their mother? Explain. ______

20.  What is the probability that Elsa and Charming’s children will be blond and have magic? (Justify your answer with at least one Punnett square).

21.  Before Elsa commits to this relationship, she wants a guarantee that her children will not have magic because she doesn’t ever have want her children to have to “conceal, don’t feel.” Provide evidence for or against this marriage based only on magical ability. ______