Question

1. for the human body to function normally, blood ph must be maintained between 7.35 and 7.45. when carbon dioxide levels in the blood rise, the ph of the blood decreases. the body then reacts to restore normal blood ph. which of the following best explains why this process is referred to as a negative feedback loop? a. carbon dioxide is removed from the body. b. it is harmful to have a decrease in blood ph. c. while a person is running, the brain sends signals to muscles. d. as carbon dioxide in the blood decreases, blood ph returns to normal.

Explanation:

Negative feedback loop is a regulatory mechanism. When carbon dioxide in blood rises (causing pH decrease), body reacts (as in option D: CO₂ decrease leads to pH return to normal). This shows variable (pH) is regulated back to set - point, which is negative feedback. Other options (A is just removal, B is about harm, C is signal - sending not feedback) don't fit negative feedback definition.

Answer:

D. As carbon dioxide in the blood decreases, blood pH returns to normal