Poruban1
Mr. PorubanGenetics ProblemsBiology
“A brown-eyed man marries a blue-eyed woman; their children had brown eyes (F1). One of these brown-eyed children married a woman with the same genes for eye color. THEIR children are shown in the Punnett square below:
F1 = Bb x Bb F2 =
B
/ bB
/BB
/Bb
b /Bb
/ bb- 25% of the children (F2) were blue-eyed. T F
- 50% of the children had the same genotype as their parents. T F
- 75% of the children were brown-eyed. T F
- All of the brown-eyed children were pure dominant. T F
- The child with blue eyes had the genotype BB. T F
- The genotype Bb is a hybrid. T F
- In a hybrid, the small letter represents a dominant gene. T F
- One of the original brown-eyed man’s parents must have been BB. T F
- The genotype for blue contains two recessive genes. T F
- There are twice as many hybrid genotypes as there are pure recessive genotypes. T F
2. In some plants, tall is dominant over dwarf .A homozygous tall plant is crossed with a short plant.
A) Assign a letter to represent the tall gene, and a letter to represent the dwarf gene.
B) Write the genotypes of both parental plants.
C) Cross the two using a punnett square.
D) Write the F1 genotypic ratio.
E) write the F1 phenotypic ratio.
3. In man, brown eyes are dominant over blue eyes. A brown-eyed man marries a blue-eyed woman and one of their children has blue eyes.
A) Assign a letter to represent the brown eye gene and the blue eye gene.
B) What are the genotypes of the parents?
C) What is the genotype of their blue-eyed child?
D) Cross the parents using a punnett square.
E) Write the F1 phenotypic and genotypic ratios.
5. Round pea seeds are dominant over wrinkled pea seeds.
A)Cross a pea plant heterozygous for round seeds with a pea plant with wrinkled seeds using a
Punnett square.
B) Show the F1 phenotypic and genotypic ratios.
C) What fraction of their offspring would you expect to have wrinkled seeds?
6. In some petunias, purple flowers are dominant over white flowers. I cross a homozygous purple with a white petunia. I really want to get some white flowers from this cross.
A) Using a punnett square, tell me the fraction of white-flowered offspring that I can expect to get.
9. In beagles, black coats are dominant over brown.
A) Cross a homozygous black beagle with a brown one and write the F1 phenotypic and genotypic ratio.
B) Cross the F1 using a Punnett square and write the F2 phenotypic and genotypic ratios.
13. A chicken which is homozygous for black feathers (B) is bred with a chicken which is homozygous for white feathers (W). ALL of their offspring has gray feathers.
A) What is the genotype of a gray chicken?
B) Cross two gray chickens using a Punnett square.
B)What is the F1 phenotypic and genotypic ratio?
14. Guinea pigs are codominant for coat color. A brown pig is BB, a white pig is WW, and a brown and white pig is BW.
A) Cross a brown pig and a white pig using a Punnett square and show the F1 phenotypic and genotypic ratios of the F1 generation.
B) Cross two F1 pigs using a Punnett square and write the F2 phenotypic and genotypic ratios.
16. If a person with Blood typeAB mates with a person with type A blood, one of their children ends up with type B blood
A) What are the phenotypes of the two parents?
B) Cross the two using a Punnett square.
C)What is the genotype of their type B offspring?
D)What is the probability that their next child would have type A?
17. Harold, whose parents had blood types of A and B, has a brother who has blood type O. Harold’s wife has blood type O, and their children have blood types A and B. Give the genotypes of Harold, his wife, his brother, his parents, and his children.
19. Hemophilia is a sex-linked recessive disease.
A) If a male hemophiliac marries a female who is normal but is heterozygous for the trait, what are their phenotypes?
B) Show a cross between the two using a Punnett square.
C) What is the probability that the two would have a hemophilic son? A hemophilic daughter?
20. A male with hemophilia is marries a normal woman with a hemophilic father.
A) What are the genotypes of the man and woman?
B) Cross the two using a Punnett square and write the F1 phenotypic and genotypic ratios.
22. Colorblindness is a sex-linked trait. A color blind male marries a female who has normal vision but whose mother was colorblind.
A) What are their genotypes?
B) Cross the two using a Punnett square and write the F1 phenotypic and genotypic ratios.