When a farmer breeds only his or her best livestock what is this process called?

Artificial selection is a form of breeding that involves human intervention.  It is a technique used by farmers to achieve desirable traits for their animals. In order to produce the “perfect offspring”, the farmers selectively choose animals to breed by manipulating heredity.

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.