Kinks in fatty acid tails cause what?

• A. Fatty acids not to pack tightly
• B. Higher density
• C. Increased rigidity
• D. Longer tails

Answer: (A)

Kinks in fatty acid tails come from cis double bonds and cause the tails to bend instead of lying straight. This bending prevents the tails from packing tightly against each other in the lipid bilayer, so the hydrophobic core has fewer van der Waals interactions and is less dense. That makes the membrane more fluid and less rigid at a given temperature. So the effect is that fatty acids do not pack tightly.

The other options don’t fit because straight, tightly packed tails would increase density and rigidity, and tail length is a separate property not dictated by kinks.