Name____________________________________________ Period ________________Date_______________________
Finding Nemo Genetics
Dihybrid Practice
1. Use the chart to identify the genotypes of the following traits for Nemo:
Trait
Dominant Gene
Recessive Gene
Color
Orange (O)
Red (o)
Body Shape
Round (R)
Oval (r)
Pattern
Striped (S)
Spotted (s)
Fin Shape
Curved (C)
Flat (c)
(a) Heterozygous orange color, oval body shape - ___________________
(b) Heterozygous striped pattern, purebred flat fin - ____________________
(c) Purebred spotted pattern, heterozygous round body - ___________________
2. Nemo’s wife, Shelia, is red and has a spotted pattern. Nemo is a purebred orange fish and
has a purebred striped pattern. He and Sheila wonder what the chances are of Shelia’s
spotted pattern trait being passed down to their kids.
(a) Identify the genotypes of Nemo and Sheila
Nemo - ____________________
Shelia - ___________________
(b) What are the possible gamete combinations for each fish?
Nemo - ____________________
Shelia - ___________________
(c) What are the possible genotypes for their children?
________________________________________________
3. (a) What are the genotypes of Dory who is heterozygous for her round body and striped
pattern and her husband Charlie, who is oval and spotted?
Dory - ____________________
Charlie - _______________________
(b) What are the possible gamete combinations for each person?
Dory - ____________________
Charlie - _______________________
(c) Complete the Punnett Square based on the information in parts (a) and (b) and
then answer the questions.
(d) What is the chance of a round baby? ________________
(e) What is the chance of a striped baby? __________________
(f) What is the chance of a round and striped baby? ________________
(g) What is the chance of a purebred recessive for both traits? ________________
4. In dolphins, gray body color (G) is dominant to blue (g), and triangular fins (T) are
dominant over rounded (t) ones. Flipper the dolphin, who is heterozygous for body color
but purebred for triangular fins, met a beautiful female dolphin named Fanny, who is
recessive for both traits.
(a) What is Fanny’s phenotype? ___________________________________
(b) Is it possible for Flipper and Fanny to have offspring that resemble Fanny?
Explain why or why not.
5. Before Flipper commits to a relationship with Fanny, he would like to guarantee that his
offspring would have triangular fins like him. You need to prove evidence for or against
their marriage. This question regards to shape of fins ONLY. Use a Punnett Square to prove
your decision, and then explain.
6. Nemo’s family brags about being a purebred line for dominant orange color. They are
also purebred for a less distinguished trait: the recessive trait of weak, asymmetrical
pectoral fins (Nemo’s dad calls it his “lucky fin”). Nemo’s weak fin causes swimming
problems and he doesn’t want his children to have to go through that. He would like to
ensure that his offspring will have strong symmetrical fins AND his orange color. Use this
information and the information in the table below to determine what traits Nemo should
look for in a mate.
Nemo’s Traits
Color
Orange (O)
Red (o)
Fins
Strong (S)
Weak (s)
(a) Must Nemo’s mate have strong pectoral fins? Explain
(b) Must Nemo’s mate be orange? Explain
7. Nemo found a potential mate in a red fish named Scarlett. Scarlett has strong pectoral
fins, but her father does not. Determine the chances of Nemo and Scarlett’s child being
orange and having strong pectoral fins.
(a) What are the genotypes of Nemo and Scarlett?
Nemo - ___________________
Scarlett - ____________________
(b) Use the genotypes in part (a) to complete the Punnett Square below and then
answer the questions
(c) For which traits, if any, is it possible for their offspring to be purebred?
(d) What is the probability that their children will be heterozygous for both traits?