Monohybrid Worksheet

Biologist:______

Period: ______Date:______

Monohybrid Worksheet

Show ALL your Work!! No work = No credit!!

Ex1. A pure-breed white flower crosses with a pure-breed purple flower. Purple (F) is dominant to white (f).

a. Determine the genotypes of the flowers. white flower: ______purple flower: ______

b. Show the punnett square.

c. What is the genotype of the F1 generation? ______

d. What is the phenotype of the F1 generation? ______

Ex2. A homozygous black guinea pig is crossed with a heterozygous black guinea pig. (B = black, b = brown)

a. Determine the genotypes of the parental guinea pigs.

homozygous black guinea pig: ______heterozygous black guinea pig:______

b. Show the punnett square.

c. What are the genotypes?______

d. What are the genotype ratio? ______

e. What are the phenotypes? ______

f. What are the phenotype ratios? ______

Ex3. If you had a black guinea pig how could you tell it’s genotype was homozygous and heterozygous?

1. In garden peas, tall vine (T) is dominant and short vine (t) is recessive. A. homozygous tall pea plant is crossed with a homozygous short pea plant.

a. Give the genotype of the homozygous tall pea plant: ______

b. Give the genotype of the homozygous short pea plant: ______

c. Complete the punnett square for the cross above:

d. What is/are the possible genotype(s) for the F1 generation: ______

e. What is the phenotype of the F1 generation: ______

2. In garden peas, tall vine (T) is dominant and short vine (t) is recessive. If a heterozygous tall pea plant is crossed with a short pea plant.

a. Give the genotype of the heterozygous tall pea plant: ______

b. Give the genotype of short pea plant: ______

c. Complete the punnett square for the cross above:

d. Give the Genotype Ratio: ______

e. Give the Phenotype Ratio: ______

3. In summer squash, white fruit color (W) is dominant and yellow fruit color (___) is recessive. A squash plant that is homozygous for a white fruit color is crossed with a squash plant that is homozygous for yellow fruit color.

a. Give the genotype of the homozygous white fruit: ______

b. Give the genotype of the homozygous yellow fruit: ______

c. Complete the punnett square to get the F1 generation:

d. F1 genotype(s):______F1 phenotype(s):______

e. Complete the punnett square for a cross between an F1 individual and a homozygous white individual?

______x ______

F1 individual White individual

f. Give the genotype ratio: ______

g. Give the phenotype ratio: ______

4. In laboratory mice, the normal gray (___) color is dominant over the white albino (g) color. A purebred albino mouse and a purebred gray mouse were mated.

a. Give the genotypes of the parents: ______x ______

albino gray

b. Complete the punnett square for the cross:

c. What is the predicted phenotype of the F1 generation? ______

d. What is the predicted ratio of phenotypes in the F2 generation?

______x ______

F1 F1

Phenotype ratio: ______

5. In mice brown is recessive (b) to black (B). A brown mouse is crossed with a heterozygous black mouse. They have a litter of four.

a. Brown mouse genotype: ______

b. Heterozygous black mouse genotype: ______

c. Show the punnett square:

d. What are the chances all four babies will be brown? ______

6. In pea plants round is dominant to wrinkled. A farmer has a field of round peas. He collects the peas and plants then for the following season. At the end of the following season he harvests 2000 pounds of peas and notices that some of them are wrinkled. List the genotypes of the offspring pea plants. What were the possible genotypes of the parental pea plants? (Use a Punnett Square and show your work)

7. Guinea pigs come in smooth and rough fur types. The rough fur is caused by a dominant allele. A student buys a rough guinea pig from a pet store, and does not know whether or not it is purebred or hybrid. What kind of guinea pig could the student mate it with to prove that it is purebred? What kind of offspring would the student have to get to prove that it is not purebred?

Probability Review

8. Albinism is a recessive disorder. Mr. Smith is albino. His wife is appears normal. They already have one albino child. What is the probability that their next child will be albino? Use a Punnett Square to show your work.

9.a. What is the probability that an even number will come up on one throw of the die?

b. What is the probability that an even number will come on both dice if two dice are rolled at the same time?

10. The Jones family has eight children, all of those whom are girls. What is the chance that the next child will be a boy? Explain how you determine your answer.