What is the role of biceps and triceps in lifting weight?

Explanation

### Step-by-Step Solution:

1. **Understanding Muscle Groups**: The biceps and triceps are two important muscle groups in the upper arm. The biceps are located at the front of the arm, while the triceps are located at the back.

2. **Role of Biceps**: When lifting a weight, the biceps contract to pull the forearm upward. This contraction allows the arm to bend at the elbow, which is essential for lifting objects towards the body.

3. **Role of Triceps**: In contrast, the triceps are responsible for straightening the arm. When the biceps are contracting to lift a weight, the triceps relax to allow this movement.

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