<span>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.</span> <span> 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).</span>
You didn't really provide any possible answers here. However, it's very easy to say that the responsible actors for impulse transmission across the synapses from one nervous cell to another nervous cell is what we call neurotransmitters. These are special molecules that can have different effects when binding onto the required receptor sites.
Answer:
Item 1 is phenotype
Item 2 genotype
The "p" represents an allele
Explanation:
