The dark band present on myofibril is

Options

A. Isotropic band
B. Anisotropic band
C. Hensen's Zone
D. M-line

Answer

**Step-by-Step Solution:**

1. **Understanding Myofibrils**: Myofibrils are the basic functional units of muscle fibers. They are composed of long chains of sarcomeres, which are the smallest contractile units of muscle tissue.

2. **Structure of Myofibrils**: Myofibrils are made up of two types of filaments: thick filaments (myosin) and thin filaments (actin). These filaments are arranged in a specific pattern that gives muscle fibers their striated appearance.

3. **Identification of Bands**: When observing a myofibril under a microscope, you will notice alternating dark and light bands. The dark bands are known as A bands, while the light bands are referred to as I bands.

4. **Composition of Dark Bands**: The dark bands (A bands) are primarily composed of thick myosin filaments, which are surrounded by thin actin filaments. This arrangement is crucial for muscle contraction.

5. **Conclusion**: Therefore, the dark band present on a myofibril is called the A band (also known as the anisotropic band).

**Final Answer**: The dark band present on myofibril is the A band.

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