Most lipids contain long chains of which two atoms

carbon and hydrogen, I believe

I know this is late, but for the people looking for the answer, its carbon and hydrogen

not sure if this what   you'r looking for would be percent composition

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.