Question

Which of the following statements is/are not true about the sarcomere?
I. The portion between consecutive Z-lines is the sarcomere.
II. I band is also called the dark band.
III. The Z-line bisects I-band.
IV. The A-band is held together by the M-line.

• A. I and II
• B. I, III, IV
• C. II and III
• D. Only II

Answer 1

The correct option is D Only II

The sarcomere is the functional unit of the muscle. It contracts and relaxes.
The region between successive Z-lines form the functional unit called the sarcomere. The I-band is also called light band or the isotropic band. The A-band is also called the dark band or the anisotropic band. The Z line bisects I band. The A band is held together by M line.
Both the actin and the myosin filaments, also called the thin and thick filaments, respectively, form the A-band. The I-band is made only of the thin filaments.