The human body must maintain a constant ph. in the blood, bicarbonate serves as a(n) to maintain the necessary ph.

Buffer.

Explanation:

Buffers may be defined as the chemicals that contains conjugate base and the weak acid . Buffer resist the pH changes of the solution when an acid or base is added to the solution.

The pH of the blood is 7.4. The bicarbonate ions acts as buffer by accepting or donating the hydrogen ions in the blood. They acts as blood buffer and resist the pH change of the body.

Thus, the answer is buffer.

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