Question

The main function of the plasma membrane
A. Maintain cell shape and size
B. Control of all cellular activity
C. Regulate the flow of materials into and out of the cell
D. Store cell material

Answer 1

Hint:-There is a unique arrangement in the cell membrane that has been clarified by the Fluid Mosaic Model. Back in 1972, this model was suggested. Over time the technology has been more mature, and it is the most commonly known plasma membrane model today.
The cell membrane encloses the other cell organelles inside it.

Complete Answer:-The cell membrane is a biological membrane also known as the plasma membrane or cytoplasmic membrane, that separates the interior of all cells from the outer world. The membrane of the cells is selectively permeable to ions and organic molecules and governs the in and out the movement of substances in the cells. The cell membrane separates the cell from the external interstitial fluid which is the main part of the extracellular fluid.
Some of the functions of the cell membrane are as follows:
- By selective permeability, form specialized compartments
- Unique favourable environment
- Developing concentration gradients
- pH and charge differences
- Asymmetrically protein distribution
- Site for receptor molecule to bind for cell signalling
- The receptor binds ligand like a hormone
- Introduce intracellular reactions
- Can "line up" the enzymes in the proper sequence

Therefore the correct answer is option (C), Regulate the flow of materials into and out of the cell.

Note:- Cell membranes are active in a number of cellular processes such as cell adhesion, ion conductivity and cell signalling, and act as the binding surface for many extracellular structures, including the cell wall, the glycocalyx a layer of carbohydrates, and the cytoskeleton fibre intracellular network of protein fibres.