What is the chemical reaction mechanism by which cells make polymers from monomers?

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.

since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.