Human skin color is a polygenic trait, which means that multiple gene loci (with different alleles) are involved in its expression. It has been shown that there more than 350 genetic loci involved in determining skin color. Because of that, there is the enormous number of possible genotypes for the skin color and as a result, the phenotypes vary from the darkest brown to the lightest hues. Different populations have different allele frequencies of genes for human skin color, and the combination of these allele variations brings about complex and continuous variation in skin coloration. Natural skin color can change due to exposure to sunlight (becomes darker) and that is the way it adapts to intense sunlight irradiation (protection against the UV exposure).
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The responses observed in type IV hypersensitivities result from the action of T cells and phagocytes.
Hypersensitivity IV type, also called delayed-type hypersensitivity (DTH), involves T cell-antigen interactions that cause activation and secretion of cytokines. This type of hypersensitivity requires sensitized lymphocytes that respond 24–48 hours after exposure to soluble antigens. A type IV hypersensitivity reaction is a cell-mediated reaction that can occur in response to contact with certain allergens, resulting in what is called contact dermatitis, or in response to certain diagnostic procedures such as the tuberculin skin test. Certain allergens need to be avoided to treat this condition. Type IV hypersensitivity response is observed results from the action of T cells and macrophages while other types are mediated by antibodies. This reaction occurs at least 1–3 days after the initial exposure. Type IV hypersensitivity is the mechanism of many autoimmune disorders.
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The answer is ‘Life insurance could be denied’. Publishing DNA results could make public genetic predisposition to diseases such as Huntington's disease, cystic fibrosis, and disorders such as Alzheimer's that are caused by environmental factors influence on the respective genetic mutations. This would cause the life and health insurers to evade such individuals since they are considered a liability. This would deny the individuals the right to health insurance.
Well, biotic factors are living things in an ecosystem such as animals or insects. Abiotic factors are non living things in an ecosystem such as sunlight or temperature. I would say biotic factors would be more harmful since this includes bacteria or other diseases, not many abiotic factors would pose a great threat to the entire human species. Hope this helped.
