Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?
A. Oxygen
B. Carbon monoxide
C. Carbon dioxide
D. Carbonic acid
The correct answer is d. Carbonic acid. When blood pH rises, carbonic acid can donate H+ ions to act as a buffer and help maintain the pH within a normal range. Carbonic acid is formed when carbon dioxide dissolves in water and reacts with it.
A. Oxygen is not responsible for donating H+ ions to act as a buffer when blood pH rises.
B. Carbon monoxide is a toxic gas that does not play a role in buffering blood pH.
C. Carbon dioxide can dissolve in water to form carbonic acid, which can then donate H+ ions to act as a buffer.
Therefore, the Correct Answer is D.