Oxygen is transported in blood mainly by

Options

A. leucocytes
B. erythrocytes
C. thrombocytes
D. blood plasma

Answer

**Step-by-Step Solution:**

1. **Understanding Oxygen Transport in Blood**: Oxygen is essential for cellular respiration and is transported in the blood to various tissues in the body.

2. **Role of Hemoglobin**: The majority of oxygen (about 97%) is transported by binding to hemoglobin, a protein found in red blood cells (RBCs). Hemoglobin can carry up to four oxygen molecules at a time.

3. **Minor Transport in Plasma**: A small percentage (about 3%) of oxygen is transported in a dissolved state in the blood plasma, which is the liquid component of blood.

4. **Identifying Blood Components**:
- **White Blood Cells (WBCs)**: These are involved in the immune response and do not transport oxygen.
- **Red Blood Cells (RBCs)**: Also known as erythrocytes, these are the primary carriers of oxygen in the blood due to the presence of hemoglobin.
- **Platelets (Thrombocytes)**: These are involved in blood clotting and do not transport oxygen.
- **Blood Plasma**: While it carries some dissolved oxygen, it is not the main transport medium for oxygen.

5. **Conclusion**: Since the majority of oxygen is transported by hemoglobin in red blood cells, the correct answer to the question is that oxygen is transported in blood mainly by erythrocytes (red blood cells).

**Final Answer**: Oxygen is transported in blood mainly by erythrocytes (red blood cells).

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