If a transporter shows Michaelis-Menten kinetics, this suggests that it binds to the molecule being transported before releasing it to the opposite side of the membrane.

Potassium ion channels have high specificity due to the ion fitting perfectly within the channel.

Ionophores tend to be polar on the outside and hydrophobic on the inside.

In secondary active transport, energy is used to transport one molecule down its concentration gradient, then the movement of that molecule against its concentration gradient is used to transport a second molecule down its concentration gradient.