The na+/k+ pump removes na+ ions and adds k+ ions.

Sodium potassium pump is an active pump which transfer sodium and potassium ions across the membrane with the expenditure of energy in the form of ATP.

This kind of pump is generally used in nerve cells.

The pump works against the concentration gradient as the pump moves three Na+ ions outside the cell and two K+ ions inside the cell, though there is a high concentration of Na+ outside the cell and a low concentration of K+ outside the cell.

b) mutualism

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- decrease the number of plants and animals living in the water.