Question

During muscular contraction, which of the following events occur?

(i) H-zone disappears

(ii) A band widens

(iii) I band reduces in width

(iv) Width of A band is unaffected

(v) M line and Z line come closer.

(a) (i), (iii), (iv) and (v)

(b) (i), (ii) and (v) (c)

(ii), (iv) and (v)

(d) (i), (ii) and (iii)

Answer 1

The correct option is (a) (i), (iii), (iv) and (v).

Explanation:

Muscle contraction is brought about by sliding of the actin filaments over myosin filaments. When a muscle fibril contracts, its A band *** constant and I band shortens. H zone also disappears as tire actin filaments of both sides as each sarcomere may overlap each other at M line.