Because they do not have an immune system, don't have noses, don't have mouths, and just plain do not have the same functions as animals, insects, or humans. They don't have a heart or a brain, which means they can't catch a cold. They can get diseases however.
What are the answer cheseis
Answer:
The involvement of more than two genes.
Explanation:
The polygenic characteristics have many phenotypes because more than two genes governs the phenotype of individual organism. The single gene contains a pair of alleles that codes for two phenotype and two genes will code for 4 phenotype. Thus, more than two genes for example, three genes will have six phenotypes.
The skin color and height are polygenic characterstics in humans.