Final answer:
Fatty acids and monoglycerides can easily diffuse directly across the cell membrane due to their hydrophobic nature and the lipid bilayer's structure.
Step-by-step explanation:
Fatty acids and monoglycerides can easily diffuse directly across the cell membrane due to their hydrophobic nature and the lipid bilayer's structure. The cell membrane is made up of phospholipids, which have a hydrophilic head and a hydrophobic tail.
The hydrophobic tails of the phospholipids create a nonpolar environment in the middle of the bilayer, allowing hydrophobic molecules like fatty acids and monoglycerides to easily pass through.
The lipid bilayer acts as a barrier to polar molecules and ions because they cannot easily pass through the hydrophobic region. However, small, nonpolar molecules like fatty acids and monoglycerides can diffuse across the lipid bilayer without the need for any transport proteins or energy.