Question

the \fluid\ part of the fluid mosaic model, that describes the structure of the cell membrane, comes from the? which are always moving, like a fluid. phosphorus molecules lipid molecules phospholipid molecules

Explanation:

The Fluid Mosaic Model describes the cell membrane. The "fluid" aspect comes from the phospholipid molecules. Phospholipids have a hydrophilic (water - loving) head and a hydrophobic (water - fearing) tail. They form a bilayer in the cell membrane. These phospholipid molecules can move laterally within the membrane, similar to a fluid. Phosphorus molecules are not the correct term here as it's about phospholipid molecules. Lipid molecules is a more general term, but specifically in the context of the cell membrane's fluidity described by the Fluid Mosaic Model, it's the phospholipid molecules.

Answer:

phospholipid molecules