Question

1. why is the structure of the plasma membrane referred to as a fluid mosaic?

Explanation:

The plasma membrane is composed of a phospholipid bilayer with embedded proteins. The phospholipids are fluid - they can move laterally. The proteins are scattered throughout like tiles in a mosaic. This gives it the appearance and properties of a fluid mosaic.

Answer:

The plasma membrane is called a fluid mosaic because the phospholipid bilayer is fluid (the phospholipids can move laterally) and has various proteins embedded in it, giving it a mosaic - like appearance.