Question

* The sarcoplasmic reticulum stores ____ when a μscle is relaxed and releases it for binding to ____ during contraction.

a) Calcium ions; troponin
b) Sodium ions; actin
c) ATP; myosin
d) Acetylcholine; sarcolemma

Answer 1

a) Calcium ions; troponin. The sarcoplasmic reticulum stores calcium ions in muscle cells and releases them for binding to troponin during muscle contraction.

Step-by-step explanation:

The sarcoplasmic reticulum is responsible for storing calcium ions in muscle cells. When a muscle is relaxed, the sarcoplasmic reticulum stores calcium ions. During contraction, the sarcoplasmic reticulum releases calcium ions to bind to troponin, which is involved in regulating skeletal muscle contraction.