Name ______Date ______
Bio 200 Period______
200 Genetics Problem Set #1
Punnett Square and Monohybrid Cross (Crosses for One Trait)
Family Guy Genetics
1. Use the information for Brian’s traits to write the phenotype for each item.
Trait Dominant Gene Recessive Gene a. BB ______
b. Tt ______
Nose Color Brown (B) Black (b) c. ff ______
d. tt ______
Ear Length Short (L) Long (l) e. Ll ______
f. Bb ______
Walking Four Legs (F) Two Legs (f) g. TT ______
h. FF ______
Communication Talking (T) Barking (t)
2. Use the information from the chart above to write the genotype(s) for each trait below.
a. Short Ears ______e. Walks on Two Legs ______
b. Talks ______f. Black Nose ______
c. Long Ears ______g. Walks of Four Legs ______
d. Brown Nose ______h. Barks ______
3. Determine the genotypes for each using information in the chart above.
a. Heterozygous Talking ______
b. Purebred Four Leg Walker ______
c. Hybrid Short Ears ______
d. Homozygous Black Nose ______
SpongeBob Genetics
1. Determine the phenotype for each genotype using the information about SpongeBob.
Yellow body color is dominant to blue.
Let ______= yellow ______= blue
YY ______Yy ______yy ______
Square shape is dominant to round.
Let ______= Square ______= round
SS ______Ss ______ss ______
2. For each phenotype, give the genotype(s) that is/are possible for Patrick.
A tall head (T) is dominant to short (t)
Tall ______Short ______
Stubby Appendages (A) is dominant to lean appendages (a)
Stubby ______Lean ______
3. SpongeBob SquarePants recently met SpongeSusie Roundpants at a dance. SpongeBob is heterozygous for his square shape, but SpongeSusie is round. Create a Punnett Square to show the possibilities that would result if SpongeBob and SpongeSusie had children.
The possible genotypes of offspring-
The possible phenotypes of offspring-
What are the chances of having a square shape child? ___ out of ____ or ______%
What are the chances of having a round shape child? ___ out of ____ or ______%
4. Everyone in Squidward’s family has light blue skin, which is the dominant trait for body color in his hometown of Squid Valley. His family brags that they are a purebred line. He recently married a nice girl who has light green skin, which is a recessive trait. Create a Punnett Square to show the possibilities that would result if Squidward and his new bride had children. Use B to represent the dominant gene b to represent the recessive gene.
The possible genotypes of offspring-
The possible phenotypes of offspring-
What are the chances of having a light blue child? ___ out of ____ or ______%
What are the chances of having a light green child? ___ out of ____ or ______%
Would Squidward’s children still be considered purebreds? Explain your answer.
Basic Crosses
The Punnett square is a chart used to predict the chances of an offspring receiving a particular trait. It will not tell you how many offspring will be produced, or the order in which they will be born.
The allele for brown hair (B) is dominant to the allele for blonde hair (b). Assume both husband and wife are heterozygous for brown hair (Bb). Use the Punnett square below to predict the genotypes and phenotypes of their offspring.
Gametes / B / bB
b
1. What are the chances of the offspring having blonde hair?
2. What are the chances of the offspring having brown hair?
3. What is the genotypic ratio?
4. What is the phenotypic ratio?
5. Is there a heterozygous blonde offspring? Why?
If curly hair is dominant to straight hair, what letters will you use to represent these genes?
6. If a heterozygous curly-haired male marries a straight-haired female, how would you write their genotypes? ______x ______
7. What would the possible gametes be for the male parent?
8. What would the possible gametes be for the female parent?
Use the Punnett square to work out the cross and then answer the questions.
Gametes9. What are the chances of the offspring being homozygous curly-haired?
10. What are the chances of the offspring having straight hair?
11. What are the chances of the offspring being heterozygous curly-haired?
12. What is the genotypic ratio?
13. What is the phenotypic ratio?
Monohybrid Cross
In fruit flies, Long wing (L) is dominant to short wing (l). Predict the outcome of the following monohybrid crosses.
1. Cross two homozygous long winged flies.
a. Parental genotypes
b. Genotypic Ratio
c. Phenotypic Ratio
2. Cross two heterozygous long winged flies.
a. Parental genotypes
b. Genotypic Ratio
c. Phenotypic Ratio
3. Cross a heterozygous long winged fly with a fly homozygous for long wings.
a. Parental genotypes
b. Genotypic Ratio
c. Phenotypic Ratio
4. Cross two short winged flies.
a. Parental genotypes
b. Genotypic Ratio
c. Phenotypic Ratio
5. Cross a short winged fly with a homozygous long winged fly.
a. Parental genotypes
b. Genotypic Ratio
c. Phenotypic Ratio
6. Cross a short winged fly with a heterozygous fly.
a. Parental genotypes
b. Genotypic Ratio
c. Phenotypic Ratio
Monohybrid Crosses
(Crosses involving two organisms heterozygous for the same trait)
1. In humans, free earlobes (E) are dominant over attached earlobes (e). A heterozygous free-earlobed male marries a female with attached earlobes. What will be the possible phenotypes and genotypes of the offspring?
2. Using the above information, cross two heterozygous free-earlobed parents and give the genotypes and phenotypes of the offspring.
3. In pea plants, round seeds are dominant to wrinkled seeds. Cross a heterozygous pea plant with round seeds with a pea plant with wrinkled seeds.
- What are the genotypes of the parents?
- What are the gametes produced by the parents?
- What are the genotypes and phenotypes of the offspring (F1 generation)?
4. Now, cross two heterozygous round-seeded plants. What will be the genotypes and phenotypes of the offspring?
5. In Labs, black fur is dominant to yellow. Explain how two black dogs can have different genotypes. Could a black dog have the same genotype as a yellow dog?
6.