Question

A.A-bands of the muscle is dark and contain myosin.
B.I-bands are the light bands and contain actin.
C.During muscle contraction the A-band contracts.
D.The part between the two Z-lines is called as sarcomere.
E.The central part of thin filament, not overlapped by thick filament is called H-zone.
Which of the above statements are correct and which are incorrect?

• A. A, B and C are correct, while D and E are incorrect.
• B. A, C, E are correct, while B and D are incorrect.
• C. A and B are correct, while C, D and E are incorrect.
• D. A, B, C and E are correct, while D is incorrect.
• E. A, B and D are correct, while C and E are incorrect.

Answer 1

Answer: (E)

A, B and D are correct, while C and E are incorrect.

Thick and thin filaments overrun which forms a dark bands called A bands. It consists of myosin. So, option A is correct.
Thin filaments alone form light bands, called as I bands and are formed of actin. So, option B is correct.
During muscle contraction sarcomeres shorten, the distance between Z-lines decreases - the width of the H and I-bands also decreases. So, option C is incorrect.
Two Z-lines delimit the unit of muscle contraction and is called the sarcomere. So, option D is correct.
The H band is within the A band where there is no overlap.
So, the correct answer is option E.