Question

if excess hydrogen ions are added to the blood, the body will respond by ______ .
a increased respiration and reabsorption of bicarbonate ions
b increased respiration and excretion of bicarbonate ions
c decreased respiration and excretion of hydrogen ions
d decreased respiration and reabsorption of hydrogen ions

Explanation:

When excess H⁺ (hydrogen ions) are added to blood, the body aims to restore pH balance. Increased respiration helps expel CO₂ (since CO₂ + H₂O ⇌ H⁺ + HCO₃⁻; less CO₂ reduces H⁺). The kidneys reabsorb HCO₃⁻ (bicarbonate ions) to act as a buffer against H⁺. Option A matches: increased respiration (to remove CO₂) and reabsorption of HCO₃⁻ (to buffer H⁺). Option B’s excretion of HCO₃⁻ would worsen acidity. Options C and D’s decreased respiration would retain CO₂ (increasing H⁺), and their ion handling is incorrect.

Answer:

A. increased respiration and reabsorption of bicarbonate ions