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

To solve the question, we need to fill in the blanks based on our understanding of how carbon dioxide is transported in the blood and the role of hemoglobin. Let's break it down step by step.

### Step-by-Step Solution:

1. **Understanding Carbon Dioxide Transport**:
- Carbon dioxide (CO2) is a waste product of metabolism and is transported in the blood to be expelled from the body. It can be transported in three main forms: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions.

2. **Identifying the Main Form of CO2 Transport**:
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