2. Wavy hair—a person that is homozygous dominant has curly hair
Wavy hair—a person that is homozygous dominant has curly hair. Homozygous recessive genotype has straight hair. A person who is heterozygous has curly hair.

3. Red-green colorblindness—the gene that codes for colorblindness is located on the x chromosome and is inherited at the same time as the x chromosome. Females are in luck because the gene is recessive. Females need two copies of the gene to be colorblind. Males only get one copy of the x chromosome so if they get one copy of the gene they are colorblind.

4. Kernel colors of corn—when corn with white kernels is crossed with corn with blue kernels the offspring will have a mix of white and blue kernels.

5. PKU—there are several alleles involved in coding for enzyme that breaks down phenylalanine. Phenylketonuria (PKU) is a disease in which the one of the alleles is mutated so a person cannot metabolize phenylalanine. The phenylalanine can build up in the person’s brain cells causing severe damage.

6. Skin color—the number of genes that contribute to skin color in humans is still being studied. There are definitely more than four genes that contribute to skin color.

7. AB blood type—B blood type (Genotypes BB or BO) has B antigens on blood cells. A blood type (Genotypes AA or AO) has A antigens on blood cells. AB blood type (Genotype AB) has A and B antigens on blood cells.

8. Cystic Fibrosis—this is a disease caused by one of several hundred alleles within the population. The phenotypes from this disease range widely from susceptibility of bronchitis to sterility.

9. Eye Color—the general eye color in humans is determined by two different genes. The eye color can also be affected by several other genes.

10. Tay-Sacs Disease—the normal human has homozygous alleles for producing LDL receptors. The LDL receptors help lower cholesterol. The homozygous genotype for not producing LDL receptors would not be able to survive. The heterozygous genotype referred to as Tay-Sacs Disease) has one allele that produces LDL receptors and one allele that does not. A person with this genotype has about half the LDL receptors of a normal person which can lead to high cholesterol levels.

11. Flower color- when red roses are crossed with white roses the result is a pink rose.

12. Chicken Feathers- A black chicken crossed with a white rooster has offspring with black and white feathers.

13. Hemophilia- people with hemophilia have blood that does not clot well
Hemophilia- people with hemophilia have blood that does not clot well. Whenever they have a cut they have excessive bleeding. This is a recessive trait and the gene for the trait is located on the x chromosome.