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Multiple Choice
Why do phospholipids form bilayers in water?
A
Because their hydrophilic tails avoid water while hydrophobic heads interact with water.
B
Because they are completely hydrophobic and repel water.
C
Because their hydrophobic tails avoid water while hydrophilic heads interact with water.
D
Because they are completely hydrophilic and dissolve in water.
Verified step by step guidance
1
Phospholipids are amphipathic molecules, meaning they have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.
The structure of a phospholipid includes a hydrophilic 'head' containing a phosphate group and two hydrophobic 'tails' made of fatty acid chains.
When phospholipids are placed in water, the hydrophilic heads are attracted to the water molecules and orient themselves towards the aqueous environment.
Conversely, the hydrophobic tails avoid water and tend to cluster together, away from the water, leading to the formation of a bilayer.
This bilayer arrangement is energetically favorable and forms the basic structure of cell membranes, with the hydrophilic heads facing the aqueous environment on both sides and the hydrophobic tails sandwiched in between.