Question

what stabilizes the phospholipid bilayer in a cell membrane? (this is another way of asking, why does a phospholipid bilayer exist?) select all that apply. hydrogen bonding between hydrophilic heads on phospholipids and water molecules inside the cell. hydrogen bonding between water molecules inside or outside the cell and polar or charged r - groups on proteins at the cell surface (either interior or exterior). hydrophobic interactions among the tails on phospholipids hydrophobic interactions between the tails on phospholipids and nonpolar r - groups on membrane proteins. hydrogen bonding between hydrophilic heads on phospholipids and water molecules outside the cell.

Explanation:

The phospholipid bilayer is stabilized by hydrogen - bonding of hydrophilic heads to water (both inside and outside the cell) and by hydrophobic interactions of the tails. The hydrogen - bonding between water and polar/charged R - groups on proteins is not directly related to the stability of the bilayer itself. Hydrophobic interactions among phospholipid tails and between phospholipid tails and non - polar R - groups on membrane proteins contribute to the stability by keeping the hydrophobic parts away from water.

Answer:

Hydrogen bonding between hydrophilic heads on phospholipids and water molecules inside the cell.
Hydrophobic interactions among the tails on phospholipids
Hydrophobic interactions between the tails on phospholipids and nonpolar R - groups on membrane proteins
Hydrogen bonding between hydrophilic heads on phospholipids and water molecules outside the cell.