Answer:
Ethanol is a non polar molecule.Therefore it passes through the cells membrane easily by diffusion like other non polar like CO2 and water.However, glycine is an amino acid ( the simplest amino acid) a charged molecule /polar molecule/.it can not therefore pass through the bilayer by simple diffusion because of the phospholipid bi-layers. Therefore special transport proteins are needed for its passage across the cell membrane.
Example-GLYT 1 and 2 are the carrier proteins specific for glycine transport across the membrane.
G
Explanation:
