Question

which situation would increase the fluidity of a phospholipid bilayer?
decreasing the temperature
increasing the number of proteins
increasing the number of cholesterol molecules
increasing the number of unsaturated fatty acids

Explanation:

• Decreasing the temperature: Reduces fluidity as molecules move less.
• Increasing the number of proteins: Proteins can restrict lipid movement, reducing fluidity.
• Increasing the number of cholesterol molecules: At high temperatures, cholesterol reduces fluidity; at low temperatures, it prevents tight packing. But overall, it's not a straightforward increase in fluidity.
• Increasing the number of unsaturated fatty acids: Unsaturated fatty acids have kinks (due to double bonds) that prevent tight packing of phospholipids, increasing fluidity.

Answer:

Increasing the number of unsaturated fatty acids.