The plasma membrane and the membranes of organelles are primarily composed of which substance?

According to the widely accepted "Fluid mosaic model", cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several respects. In this regard, which of the following statements is incorrect?

Identify $X, Y, Z$ from the given figure of the cell membrane:

An example of a selectively permeable membrane is

In human beings,the membrane of the erythrocytes has approximately ...... percent protein and ....... percent lipids.

The plasma membrane is composed of