Why is blood needed by all the parts of a body?

Explanation

### Step-by-Step Solution:

1. **Introduction to Blood**: Blood is a vital fluid in the body that performs several essential functions. It consists of different types of cells, primarily red blood cells (RBCs), white blood cells (WBCs), and platelets.

2. **Function of Red Blood Cells (RBCs)**: The primary role of RBCs is to transport gases. They carry oxygen from the lungs to all parts of the body and bring carbon dioxide (CO2) back to the lungs for exhalation. This gas exchange is crucial for cellular respiration, which is how cells produce energy.

3. **Function of White Blood Cells (WBCs)**: WBCs are responsible for the immune response. They help fight infections and protect the body from pathogens. This function is essential for maintaining health and preventing diseases.

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