OTHER PATTERNS OF INHERITANCE

1. The Punnett squares both show a cross between a plant that produces red flowers and a plant that produces white flowers. What is the genotype of the plant with red flowers? Is it homozygous or heterozygous?

The genotype of the plant with red flowers is RR and it is homozygous dominant.

2. What is the genotype of the plant with white flowers? (Write both versions.) Is it homozygous or heterozygous?

The genotype of the plant with white flowers is WW and R’R’ and they are both homozygous dominant.

3. All of the offspring are plants that produce pink flowers. What must have happened in order to produce pink flowers?

Incomplete dominance must have happened in order to produce pink flowers. 

4. What are the genotypes of the offspring? (Write both versions.) Are they homozygous or heterozygous?

All of the offsprings from both Punnett squares are homozygous dominant with RW and RR’ being the genotypes.

5. What does incomplete dominance mean?

Incomplete dominance means that neither allele is dominant.

6. Why are all of the alleles written with capital letters? 

All of the alleles are written with capital letters because all of the alleles are homozygous dominant.

7. What two methods are used to write alleles for incomplete dominance? (Both methods are used regularly.)

Either the allele and then the allele prime (ex. RR and R’R’, making RR’ offspring), or to different alleles (ex. RR and WW making RW offspring).

9. What is the genotype of the black chicken? What is the genotype of the white chicken? Are they homozygous or heterozygous?

The genotype of the black chicken is BB and the genotype of the white chicken is WW. The genotypes of both chickens are homozygous.

10. What is the genotype of the offspring? What is the phenotype of the offspring? Is the offspring homozygous or heterozygous?

The phenotype of the offspring is a mix of both black and white feathers on the chicken. The offspring is neither homozygous nor heterozygous, as it has two different alleles for traits, but both of the alleles are dominant for that specific trait. 

11. If this trait was an example of incomplete dominance, what color would the chicken’s feathers be?

If this trait was an example of incomplete dominance, the color of the chicken’s feathers would be gray.

12. If the plants with red flowers and white flowers experienced codominance, what color flowers would a heterozygous plant have?

The color of the flowers of a heterozygous experiencing codominance, we will see red and white flowers in the same plant, but they will not mix and make pink.

13. What is the difference between incomplete dominance and codominance? What happens in Mendel’s complete dominance?

Incomplete dominance is the blend of both parents’ genotypes, creating a new phenotype in their offspring. Codominance is when both parents’ phenotypes are expressed together in their offspring. In Mendel’s complete dominance, one allele is 

dominant over the other recessive allele.

19. Which allele is dominant: B or O? Explain your answer.

The allele B is dominant over O because the genotype of BB and BO result in the same phenotype, meaning the allele O is recessive.

20. Which allele is dominant: A or B? Explain your answer.

Neither allele is dominant as in the genotype AB, the phenotype contains both traits of the allele A and B, meaning they experience codominance.

21. Is blood type an example of incomplete dominance or codominance? (Hint: You may want to refer back to the picture.) Explain your answer.

Blood type is an example of codominance as the blood type AB contains both traits of both the A allele and B allele, meaning they experience codominance.

26. Why are both capital and lowercase letters used?

To show that the female is heterozygous and a carrier for a recessive allele trait.

27. Why doesn’t the Y chromosome have a superscript?

Because most sex-linked traits are carried on the X chromosome.

28. Hemophilia is a recessive, sex-linked blood disorder. In this example, we will use H to designate the normal blood-clotting allele and h to designate the hemophilia allele. Can a person have hemophilia if they have a copy of the dominant H allele? Explain your answer.

No, a person with a copy of the dominant H allele cannot have hemophilia, as hemophilia is a recessive trait. This individual may be a carrier for hemophilia if the are heterozygous 

29. How many X chromosomes do males have? How many copies of the H/h blood-clotting allele will a male inherit? Explain your answer.

Males have 1 copy of the X chromosome and the male would inherit one copy of the H/h blood clotting allele. 

30. List all of the possible genotypes associated with hemophilia. (Four of them are in the Punnett square.) Determine whether a person with those genotypes will have hemophilia. (Remember it is a recessive trait.)

31. Looking back at the Punnett square in #24, does the father have hemophilia? Explain your answer.

No, the father does not have hemophilia, as he has a dominant allele.

32. Does the mother have hemophilia? Explain your answer.

No, the mother does not have hemophilia, but she is a carrier for hemophilia as she is heterozygous for hemophilia. 

33. Are males or females more likely to be affected with a recessive, sex-linked disorder? Explain your answer.

Males are more likely to be affected with a recessive sex linked disorder becuase if they recive a recessive allele for a trait, they cannot also recive a dominant allele for the same trait, making them unable to be heterozygous for the trait.