Amphipathic Nature of Phospholipids

Steps:

• Recall that phospholipids have a polar head and nonpolar tails.
• Understand that the polar head is hydrophilic, attracting water.
• Note that the nonpolar tails are hydrophobic, repelling water.
• Recognize that in water, these molecules arrange into a bilayer with heads facing water and tails inward.

Why C is correct:

• Phospholipids are amphipathic, with hydrophilic phosphate heads and hydrophobic fatty acid tails, driving spontaneous bilayer formation as defined by the hydrophobic effect in aqueous environments.

Why the others are wrong:

• A: Insolubility alone does not explain bilayer structure; it relates to overall amphipathicity.
• B: Solubility would disperse molecules, preventing organized bilayer formation.
• D: Fatty acid saturation affects fluidity but not the fundamental ability to form a bilayer.

Final answer: C