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 arrows usually point to the organisms that are doing the eating.
Explanation:
For that reason, we can say that the arrows represent the flow or transfer of energy in an ecosystem. It also specifies the direction of the flow of energy.
<span>the high expense; electron microscopes are costly</span>
The white blood cell identifies the toxin produced by the pathogen and creates antibodies to fight the pathogen