Question

Cell wall is absent in which of the following?
A.Plants
B.Animals
C.Mucor
D.Bacteria

Answer 1

Cell wall is present outside the cell membrane. It is a structural layer which can be tough, flexible, and maybe rigid. It is known for its structural support, protection and acts as a filtering mechanism. Its composition varies from species to species and may depend on cell type and developmental stage.

Complete step by step answer: Option -A- Plants
The cell wall is present in plants outside the cell membrane. They have much tensile strength to withstand internal osmotic pressure. There are three layers in the cell wall of the plants including primary cell wall, secondary cell wall, and middle lamella made up of pectins. The composition of the cell wall in land plants is polysaccharides, hemicellulose, and pectin. Other polymers include lignin, cutin, etc.
Option -B- Animals
In animal cells, the cell wall is absent outside of the cell membrane. In animal cells, they have an exoskeleton and outer covering of the cell which is the plasma membrane is composed of protein and lipid which is known for its function of protection of the internal structure of animal cells. This is the reason they lack a cell wall.
Option -C- Mucor
Mucor is a fungal group that does have a cell wall outside its cell membrane. They have three main components of cell wall which are chitin, glucans (glucose polymers linked with chitin), and some proteins which are enzymes necessary for cell wall synthesis and provide structural support.
Option -D- Bacteria
Bacteria do have a cell wall outside their cell membranes. The cell wall is made up of polysaccharide chains cross-linked by peptides having D-amino acids. Cell wall in bacteria is of two types: gram-positive and gram-negative based on the Gram stain they take. Gram-positive bacteria have peptidoglycan and teichoic acid. Gram-negative bacteria have few layers of peptidoglycan and a second layer of lipopolysaccharide and lipoproteins.
So, the correct answer to this question is the option"B".

Note: The major function of the cell wall is they act as pressure vessels, by this, they prevent the over-expansion of the cell when the water enters and prevent bursting of the cells. Cell walls as such perform many functions.