Question

25. to conserve water, an animals kidneys can pump ions across cell membranes, allowing water to move by________?

Answer 1

Answer:

Active Diffusion

Explanation:

In active transport, a molecule is transported against its gradient which means the flow of molecule is from regions of low concentration to regions of high concentration. In order to carryout such transports, external energy is applied through biological pumps such as sodium-potassium pump (Na+/K+ ATPase)  which maintains the resting potential of the cell.  

Some times the energy produced by ATP is directly used and this process is known as primary active transport/diffusion

Answer 2

Active deffusion.. this way the water is retained and the unnecessary salts ions are expelled out.