Air must pass from the back to the front of the pharynx to enter the trachea and food must pass from the front to the back of the esophagus
Plasma membrane is a part of the cell made of a lipid bilayer and an embedded protein layer. It protects the cell from the surroundings and also controls the materials leaving or entering the cell. The membrane is semipermeable and therefore allows certain materials to enter or leave the cell. In this case, the plasma membrane may prevent unlimited flow of water into or out of the cell.
A new moon
Definition of new moon:
the phase of the moon when it is in conjunction with the sun and invisible from earth, or shortly thereafter when it appears as a slender crescent.