One of the most important functions of the plasma membrane is the transport of the molecules across it. Which of the following statement is incorrect regarding active transport?

Transport of few ions or molecules across the membrane against the concentration gradient occurs with the help of active transport.

Active transport is the only means of transportation of polar molecules as they cannot pass through the nonpolar lipid bilayer.

Energy is required for this type of transport.

    Active transport is carried out by specific membrane-proteins.