Myofibrils are structural constituent of muscle fibre, select correct statement for myofibril:

(i) Each myofibril has alternate dark and light bands on it.

(ii) Striated appearance of myofibril is due to the distribution pattern of two important proteins-actin and myosin.

(iii) The light bands contain myosin and is called I-band or isotropic band, whereas the dark band called A or Anisotropic band contains actin.

(iv) Actin filaments are thicker as compared to the myosin filaments, hence are commonly called thick and thin filaments respectively.

(v) In the center of each A-band is an elastic fibre called Z-line which bisects it.

(vi) The thick filaments in the A-Band are held together in the middle of this band by a thin fibrous membrane called M-line

(vii) The portion of the myofibril between two successive Z-lines is considered as the functional unit of contraction and is called a sarcomere.