Reference no: EM133511173

Assignment: Punnett Squares

Part A: Incomplete and Co-Dominance

List the parent genotypes, draw and fill in a Punnett square, and indicate the phenotypic ratio (for each possible trait combination). SHOW ALL WORK.

I. Snapdragons are flowers that come in both Red and White. When the two are crossed they are incompletely dominant.

1. Cross a red snapdragon with a white one.
2. Now, cross two of the F1 offspring from the previous cross and show what the outcome is.

II. In chickens, F is the trait for frizzled feathers and S is the trait for straight feathers. Since both are dominant, when they are inherited together, the result is a "slightly frizzled" chicken.

Complete the following crosses:

1. frizzled x straight feathers
2. slightly frizzled x slightly frizzled feathers
3. frizzled x slightly frizzled feathers

Part B: Dihybrid Crosses

List the parent genotypes, draw and fill in a Punnett square, and indicate the phenotypic ratio (for each possible trait combination).

I. A tall green pea plant (TtGg) is crossed with a Short white pea plant (ttgg).

II. A Homozygous tall, green flowered plant is crossed with a Homozygous short white flowered plant.

III. Two Heterozygous Tall, Green pea plants are crossed.

Part C: Probability Problems

Set up Punnett Squares to determine the probabilities of each phenotype below. Remember there are TWO ways to determine probability...choose whichever works best for you. SHOW ALL WORK.

Dominant allele for tall plants = T Recessive allele for dwarf plants = t Dominant allele for purple flowers = P Recessive allele for white flowers = p

I. Cross a heterozygous parent with a homozygous dominant parent.

II. Using the Punnett square(s) in question #1:

1. What is the probability of producing tall plants with purple flowers? Possible genotype(s)?
2. What is the probability of producing dwarf plants with white flowers? Possible genotype(s)?
3. What is the probability of producing tall plants with white flowers? Possible genotype(s)?
4. What is the probability of producing dwarf plants with purple flowers? Possible genotype(s)?

III. A man with Type AB blood and dark hair (heterozygous) has a child with a woman with Type AB blood and light hair. What is the probability that they will have a child with Type B blood and dark hair.

IV. A woman with normal vision whose father was color-blind is expecting a child. Her partner is color-blind. What are the chances they will have a daughter who is color-blind?

V. A man who is a dwarf with achondroplasia (heterozygous for the dominant trait) and normal vision marries a color-blind woman of normal height. How many of their sons might be expected to be color¬blind with achondroplasia?