Question

Biological membranes are held together mainly by ______

a.hydrogen bonds between lipid molecules
b.hydration layers over lipid molecules
c.exclusion of the nonpolar regions of lipids by water
d.hydrogen bonds between water molecules
e.surface tension at the interface between layers of water molecules

Answer 1

Biological membranes are primarily held together by hydrophobic forces that cause the exclusion of nonpolar lipid regions by water, leading to a stable cell membrane structure with hydrophilic surfaces and a hydrophobic core.

Step-by-step explanation:

Biological membranes are held together mainly by the exclusion of the nonpolar regions of lipids by water. This occurs because the membrane's main fabric is composed of amphiphilic, phospholipid molecules that contain both hydrophilic ('water-loving') and hydrophobic ('water-hating') regions. The hydrophilic heads of these molecules are in contact with aqueous fluid both inside and outside the cell, while the hydrophobic tails face each other within the interior of the membrane. This arrangement creates a hydrophobic barrier between two hydrophilic surfaces, forming the stable structure of the cell membrane.