Bio chemical changes in muscle contraction were explained by ………….. .

Explanation

**Step-by-Step Solution:**

1. **Understanding Muscle Contraction**: Muscle contraction involves a series of biochemical changes that allow muscle fibers to shorten and generate force.

2. **Role of Calcium**: The process begins when calcium ions are released into the muscle fibers. These calcium ions bind to a protein called troponin, which causes a change in the structure of another protein called tropomyosin.

3. **Exposure of Active Sites**: The binding of calcium to troponin causes tropomyosin to move away from the active sites on actin filaments, exposing these sites for interaction with myosin.

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