Question

Assess the statements.
1. A-bands of the muscle is dark and contain myosin.
2. I-bands are the light bands and contain actin.
3. During muscle contraction the A-band contracts.
4. The part between the two Z-lines is called as sarcomere.
5. The central part of thick filament, not overlapped by thin filament, called H-zone.
Of the above statements.

• A. 1, 2 and 3 are correct while 4 and 5 are incorrect.
• B. 1, 3, 5 are correct while 2, 4 are incorrect.
• C. 1 and 2 are correct while 3, 4 and 5 are incorrect.
• D. 1, 2, 3 and 5 are correct while 4 is incorrect.
• E. 1, 2, 4 and 5 are correct while 3 is incorrect.

Answer 1

The correct option is E 1, 2, 4 and 5 are correct while 3 is incorrect.

The basic unit of the striated muscle tissue are the sarcomeres, a structure made up of highly organized contractile myofilaments that are stacked up in regular arrays. The striation is made up of thin and thick protein filaments. Electron microscopic studies show thin filaments of actin which make up the I bands and thicker filaments of Myosin which make up the A bands giving it a darker appearance. Z line is the border of the sarcomere where the actin molecules are bound. Muscle contractions result in the shortening of the I bands whereas the A bands do not change. The H zone is the region in which the central part of the thick filament has not been overlapped by the thin filament.