Question

Choose the correct statement about the key difference between the cell wall and the cell membrane.
A. The cell membrane is present in all cells but the cell wall is only present in plants, bacteria, fungi, and algae.
B. The cell membrane is present in all cells except algae but the cell wall is only present in plants, bacteria, fungi, and algae.
C. The cell membrane is present in all cells except fungi but the cell wall is only present in plants, bacteria, fungi, and algae.
D. The cell membrane is present in all cells except plants but the cell wall is only present in plants, bacteria, fungi, and algae.

Answer 1

The word cell membrane refers to a semipermeable membrane of a cell that surrounds the cell and encloses its cell organelles, cytoplasm, and nucleoplasm. The cell membrane is also referred to as the plasma membrane or cytoplasmic membrane. Cell wall refers to a covering of the cell membrane which is mostly seen in prokaryotes.

Complete step by step answer: Cell wall is a type of covering seen in some kinds of cells. Cell wall bounds or surrounds the cell membrane and acts as a semipermeable membrane. The role of structural support, protection, and filtering mechanism is provided by the cell wall. It is mostly seen in all prokaryotic organisms like bacteria, fungi, and algae. The cell wall is also seen in eukaryotes which include plants. The composition of cell walls varies depending upon the species. Mainly the cell wall is composed of cellulose, pectin, and hemicellulose. Various other polymers like lignin, chitin are also embedded in the cell wall of plants. A semipermeable membrane which surrounds and encloses the cell organelles, cytoplasm, and nucleoplasm of the cell is called a cell membrane. The cell membrane is responsible for separating the cell from the interstitial fluid. The cell membrane is mostly made up of bilipid layers which are present between the phospholipid layer. The primary function of cell membranes is to conduct the transfer of proteins and other biomolecules by osmosis or diffusion.
Therefore, it is clear that the cell membrane is present in all cells but the cell wall is only present in plants, bacteria, fungi, and algae.
So, option A is the correct option.

Note: Even though the cell wall is present in all prokaryotic organisms there is an exception. It is absent in mollicute bacteria. In eukaryotes, the cell wall is absent in animals and humans. Bacteria that belong to prokaryotes are further classified as gram-positive and gram-negative bacteria. Gram-negative bacteria possess both a plasma membrane and another membrane which separates the periplasm.