Which taste of food can be detected :
by the back part of the tongue?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Tongue's Structure**: The tongue has different regions that are sensitive to various tastes. It is important to know that different parts of the tongue are responsible for detecting different flavors.

2. **Identifying the Types of Tastes**: There are four primary tastes that can be detected by the tongue: sweetness, bitterness, saltiness, and sourness.

3. **Locating the Taste Sensitivity**:
- **Sweetness** is detected by the tip of the tongue.
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