Question

what is the primary function of the cell membrane? *
acts as a barrier
controls what can come in and out of the cell
allow for cell communication
all of the above

which statement best describes the fluid mosaic model of the cell membrane? * 1 point
a rigid structure made of proteins only
a flexible layer of phospholipids with proteins embedded throughout
a solid wall of lipids with carbohydrates on the surface
a double layer of proteins with lipids scattered inside

Explanation:

For the first question:

• The cell membrane acts as a barrier (physical separation).
• It controls the entry and exit of substances (selective permeability).
• It also allows for cell - cell communication (e.g., through receptor - ligand interactions). So all the functions mentioned are correct.

For the second question:

• The fluid mosaic model describes the cell membrane as a flexible layer.
• It is composed of a phospholipid bilayer (the basic structure) with proteins embedded throughout (integral proteins), some on the surface (peripheral proteins), and also has carbohydrates attached to lipids or proteins on the surface.

Answer:

First question: D. All of the above
Second question: B. A flexible layer of phospholipids with proteins embedded throughout