The building blocks of proteins are known as amino acids. These acids are not only the building blocks of proteins--they are also important in many other chemical and biological processes.
Even though facilitated diffusion involves transport proteins, it is still passive transport because the solute is moving down the concentration gradient. ... A channel protein, a type of transport protein, acts like a pore in the membrane that lets water molecules or small ions through quickly.
I don’t to be honest but my guess would be lithosphere , Hope it helps