Some animals, but not humans, have an organ called a gizzard located near the top of their digestive tract. this organ is small and can contain small rocks. it also has thick, muscular walls. based on this physical description, which of the following is most likely to be the function of this organ?

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.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.