Question

Electron microscopic studies of the sarcomeres have revealed that during muscle contraction (a) The width of A-band remains constant (b) The width of the H-zone becomes smaller (c) The width of I-band increases (d) The diameter of the fibre increases.
Its answer given is option a ,my question is why option a and b both are not given both should be correct...

Answer 1

HEY MATE!!!!❤❤❤HERE'S UR ANSWER!!!
THE CORRECT OPTION IS (B) THE WIDTH OF THE H-ZONE BECOMES SMALLER.
HOPE THIS HELPS YOU

Answer 2

(A) The width of A-band remains constant

Explanation:

• The sarcomere is the functional unit of a muscle fibre which is made up of actin and myosin.
• The structure of the sarcomere is divided into the bands called A bands which are made of both actin and myosin. The portion of A band which is made of the myosin is known as H zone and which the portion which is made of the actin only is known as the I band.
• During muscle contraction, when the myosin slides over the actin, both the actin and myosin moves and their zone, the H zone and I band gets shorten. However, the A band does not shorten and remains the same.

Thus, Option-A is the correct answer.

To learn more:

1. https://brainly.in/question/3288288