Question

Cytological examination of resting and contracted muscle provides important support for the sliding filaments model for how skeletal muscle contracts. This evidence includes the observation that during contraction the

A) Z lines move farther apart.
B) lengths of the thick filaments shorten significantly.
C) lengths of the thin filaments shorten significantly.
D) I bands get longer.
E) H zone becomes narrower.

Answer 1

During muscle contraction, the I bands get longer and the H zone becomes narrower. This observation supports the sliding filaments model for skeletal muscle contraction.

Step-by-step explanation:

The observation that supports the sliding filaments model for skeletal muscle contraction is that during contraction, the I bands get longer and the H zone becomes narrower.

In a contracted muscle cell, the H zone, which contains only thick filaments, almost disappears. The A band, which contains both thick and thin filaments, stays the same width during contraction.

This evidence aligns with the sliding filament model, which proposes that muscle contraction occurs when thick and thin filaments slide past each other, resulting in the shortening of the sarcomere.