Discuss the role of `Ca^(2+)` ions in muscle contractions. Draw neat sketches to illustrate your answer.

Explanation

### Step-by-Step Solution

1. **Introduction to Muscle Contraction**:
- Muscle contraction involves two primary contractile proteins: actin and myosin. These proteins interact to facilitate muscle movement.

2. **Role of Troponin**:
- Actin is associated with a regulatory protein called troponin. Troponin plays a crucial role by masking the active sites on actin, preventing myosin from binding to actin when the muscle is at rest.

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