Question

H-zone of striated muscle fibre represents both thick and thin filaments.
A. True
B. False.

Answer 1

Hint: A sarcomere is referred to as the length between two consecutive Z lines or Z discs; when a muscle shrinks or contracts, then the length between the Z discs is decreased. The H zone the middle area of the A zone does not contain auxin and is shorter during contraction.

Complete answer:
To answer this question, first, we need to know about the striated muscle. Striated muscle tissues are muscle tissues that attribute repeating functional units referred to as sarcomeres. The presence of sarcomeres manifests as a series of bands visible along the muscle fibers, which is responsible for the striated appearance observed in microscopic images of this tissue.
Now, let us find the solution from the option.
>Myofibril activity is required for contraction of muscle on the molecular phase.
>When ATP binds to myosin, it separates from the action of the myofibril, which causes a contraction.
>Creatine phosphokinase helps in the regeneration of ATP. H zone with no actin vanish and Z zone goes towards each other.
>The muscle contraction cycle is activated by calcium ions tied with the protein component troponin, producing the active-binding sites on the actin.
>ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.

Thus, the correct option is B. i.e. False.

Note:Each muscle fibre has many parallely arranged myofibrils. Each myofibril consists of more sequentially aligned units referred to as sarcomere that are the functional blocks. In a relaxed form, the sharp corner of thin filaments on either side of the thick filaments partly grows the free ends of the thick filaments left in the middle portion of the thick filaments. This middle portion of thick filament, not lapped over by thin filaments is known as the ‘H’ zone.