What role does carbonic acid (h2co3) play in the human body?

The carbonic acid lowering the blood pH by breakdown into a bicarbonate, and proton ion. Carbonic anhydrase is known as an enzyme which helps to enable the breathing out CO2, and the balance the pH of the blood.

Bicarbonates are known as the intermediate in the transport of carbon dioxide out of the body by the process of respiratory gas exchange. Carbonic acid which is known as a weak acid forms 2 types of salts one is carbonates, and another is bicarbonates.

it has one origin of replication, but it proceeds in two directions - d)

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.