Most carbon dioxide is transported in blood in the form of ........................ ions. Hydrogen ions formed when carbon dioxide enters blood become attached to ..... so that the addition of carbon dioxide causes only a small decrease in blood pH.

Explanation

**Step-by-Step Solution:**

1. **Understanding Carbon Dioxide Transport**:
- Carbon dioxide (CO2) is a waste product produced by cells during metabolism. It needs to be transported from the tissues to the lungs for exhalation.
- CO2 is transported in the blood in three main forms: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions (HCO3-).

2. **Identifying the Primary Form of CO2 Transport**:
- The majority of CO2 (about 70%) is transported in the form of bicarbonate ions (HCO3-). This occurs when CO2 reacts with water in the presence of the enzyme carbonic anhydrase, forming carbonic acid, which then dissociates into bicarbonate and hydrogen ions.
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