Answer: The correct answer is D.
Explanation:
Calcium is not actively transported from an organelle into the cytosol.
Calcium Pumps are protein pumps that moves Ca2+ back into the sarcoplasmic reticulum (a modified Endoplamic Reticulum) in skeletal muscle after each contraction. They belong to the ion transporters protein family.
In calcium homeostasis these pumps are basically ion transporters located on the cell membrane of all animal cells. They help to pump Ca2+ out of the cell to maintain electrochemical gradients across the cell membrane.
The pump on the the call membrane are Ca2+ ATPase (PMCA) and Sodium-calcium exchanger and they actively pumped out Calcium of cytosol •
The calcium pump has high affinity for Ca2+ but low capacity to push out Ca2+ where as NCX has low affinity for Ca2+ but high capacity to pump out Ca2+•
