Active transport goes against the concentration gradient (from low to high), unlike osmosis and diffusion which travel with a concentration gradient (from high to low).

Also, active transport needs energy (ATP).

Active transport needs energy, as it is going against a concentration gradient, and needs energy to rotate the protein transporting the solute.

The energy is produced in respiration and comes from the mitochondria.

The higher the rate of respiration, the higher the rate of active transport.

Mineral ions in the soil are usually in dilute solutions, more dilute than the solution in the plant cells. Active transport allows these mineral ions to be absorbed by the plant, against a concentration gradient.

In the human body, glucose is moved out of the gut and kidney tubules and into the blood, against a concentration gradient, using active transport.

These marine creatures take in too much salt from the sea water that they drink and the kidneys can't get rid of it.

Special salt glands are found near the eyes and nostrils, and sodium ions are moved here. These ions have to be moved against a very big concentration gradient, meaning active tranport is vital for the birds' and reptiles' survival.

Cyanide stops the respiration reactions in the mitochondria from happening. This stops active energy, as there is no source of energy.

However, if the cells are provided with energy, active transport will start up again even though the mitochondria are still poisoned.