What is and allele I need help pls

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Explanation:

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.

colors do exist. the color of the sky is actually violet; humans percieve the color of the sky as blue.