Answer:
Ribose
Explanation:
Ribose, also called D-ribose, five-carbon sugar found in RNA (ribonucleic acid), where it alternates with phosphate groups to form the “backbone” of the RNA polymer and binds to nitrogenous bases.
Increasing substrate concentration also increases the rate of reaction to a certain point. Once all of the enzymes have bound, any substrate increase will have no effect on the rate of reaction, as the available enzymes will be saturated and working at their maximum rate.
Protein channels + no energy spent + following concentration gradient = passive transport via facilitated diffusion :)