Question

During muscle contraction

• A. the A band remains the same and the I band narrows.
• B. the I band remains the same and the A band narrows.
• C. both the A band and I band remain the same.
• D. both the A band and I band narrow.

Answer 1

The correct option is A

the A band remains the same and the I band narrows.

Upon muscle contraction, the A-bands do not change their length, whereas the I-bands and the H-zone shorten. This causes the Z lines to come closer together.