Question

Which of the following steps are out of order in the muscle contraction cycle?

1) steps 1 2
2) steps 2 3
3) steps 3 4
4) steps 4 5

Answer 1

Following steps are out of order in the muscle contraction cycle 3) steps 3 4.

Therefore, correct option is 3) steps 3 4

Step-by-step explanation:

In the muscle contraction cycle, steps 3 and 4 are out of order. During muscle contraction, the sequence generally follows the excitation-contraction coupling process. Step 3 involves calcium ions binding to troponin, exposing binding sites on actin. Step 4, on the other hand, corresponds to the cross-bridge formation between myosin and actin, a step that occurs after the binding sites are exposed.

The correct sequence is typically 1) neural stimulation (excitation), 2) release of calcium ions, 3) exposure of binding sites on actin, 4) cross-bridge formation, and 5) sliding of filaments leading to muscle contraction.

Therefore, correct option is 3) steps 3 4