Question

why are lipids and proteins free to move laterally in membranes?
the interior of the membrane is filled with liquid water.
lipids and proteins repulse each other in the membrane.
phospholipids form hydrogen bonds with water at the membrane surface, which moves the lipids as water moves.
weak hydrophobic interactions in the interior of the membrane are easily disrupted.

Explanation:

• The interior of the membrane is not filled with liquid water. The membrane has a lipid - bilayer structure.
• Lipids and proteins do not repulse each other in a way that would cause lateral movement. There are various interactions between them.
• Phospholipids form hydrogen bonds with water at the membrane surface, but this is not the main reason for lateral movement of lipids and proteins within the membrane.
• The fluid mosaic model of the membrane suggests that the membrane is fluid. The weak hydrophobic interactions in the interior of the membrane (between the non - polar tails of phospholipids) are easily disrupted, allowing lipids and proteins to move laterally.

Answer:

Weak hydrophobic interactions in the interior of the membrane are easily disrupted.