Which exemplify active transport?

The proteins that transport ions across membranes fall into two general classes: passive conduits called ion channels, through which ions rush down gradients of concentration, and pumps that release energy from ATP or other source to actively push ions against those gradients and so build them up.

Aquaporins are specialized proteins that allow the movement of water across the cell membrane. However, the movement of water across the cell membrane through aquaporins is a passive process because it occurs in the direction of the concentration gradient of water molecules.

The movement of food in the phloem sieve tube elements occurs through a process called translocation. This process does not require energy. Hence, it is a passive process.