Answer :FACILITATED DIFFUSIION
Explanation;Generally polar molecules like glucose, amino acids and Ions such as potassium and sodium can not enter or leave the cell through the phospholipid bilayer membrane of the cell. They are assisted to pass accross this barrier with the help of (1) channel proteins 2) carrier proteins.
The process by which these proteins created hydrophilic (water loving environments) to carry out transport of the above molecules and ions accross the hydrophobic (water hating environment) phospholipid membrane layer to reach the cytoplasm of cells is called facilitated diffusion.
This transport process is not active transport, because the moleucules moved down their concentration gradients.
Water- filled pores made up Channel proteins. They allows charged ions to pass through, therefore Ion channels are example of channel proteins; for example Potassium channels, Calcium channels. They are gated, thus the protein parts can move back and front like a gate to close or open the pores like a <u>Gate. Channels proteins are fixed.</u>
Carrier proteins are flexible and change the shapes with respect to the direction to convey the molecules accross the membrane, they are not fixed.
