Active transport makes it possible for cells to:. a. transport out secretory products and waste material against concentration gradients.
b. take up nutrients from the environment against concentrations gradients.
c. maintain nonequilibrium intracellular concentrations of ions such as Na , K , Ca2 , and H .
d. establish an electrical potential across the membrane.
e. All of the above are correct.

e. All of the above are correct.

Explanation:

Active transport is a type of transport in living systems in which molecules/ions/substances are moved or transported against their concentration gradient i.e. from a region where the substance is LOW to a region which it is HIGH, across a membrane. Since molecules are transported across a memembrane against their concentration gradient, an energy input in form of ATP is needed to do so.

Active transport is used in living systems to transport out secretory products and waste material against concentration gradients, take up nutrients from the environment against concentrations gradients etc. Since ions are substance moved by active transport from a low region to high region, there is an imbalance in the intracellular concentration of ions, such as Na, K etc.

Since there is no equilibrium in the concentration of ions on opposite sides of the membrane, an electric potential is formed across the membrane i.e. one part of the membrane will be more positively charged than the other.