Cell Wall – Structure, Composition & Functions (NEET Biology)

Chapter: Cell – The Unit of Life
Topic: Cell Wall (Plant Cell)
Exam Focus: NEET

Introduction

The cell wall is a rigid, non-living outer covering present outside the plasma membrane of plant cells, fungi, and some prokaryotes.
It provides shape, protection, and mechanical strength to the cell.

📌 Animal cells do not have a cell wall.

What is Cell Wall?

The cell wall is a freely permeable structure that surrounds the plasma membrane of plant cells.
It is mainly made up of cellulose.

Chemical Composition of Cell Wall

1️⃣ Cellulose

• Main component of plant cell wall

• A polysaccharide made of glucose

• Provides rigidity

2️⃣ Hemicellulose

• Binds cellulose fibers

• Provides flexibility

3️⃣ Pectin

• Cementing material

• Found in middle lamella

4️⃣ Lignin

• Found in secondary wall

• Provides hardness (e.g., wood)

Structure of Cell Wall

1️⃣ Middle Lamella

• Outermost layer

• Made of calcium pectate

• Joins two adjacent cells

2️⃣ Primary Cell Wall

• Thin and elastic

• Found in young, growing cells

• Allows cell growth

3️⃣ Secondary Cell Wall

• Thick and rigid

• Found inside primary wall

• Contains lignin

• Provides maximum strength

Functions of Cell Wall

• Gives definite shape to cell

• Protects cell from mechanical injury

• Prevents bursting of cell

• Maintains turgidity

• Allows free diffusion of substances

Plasmodesmata

Plasmodesmata are cytoplasmic connections between adjacent plant cells.

Functions:

• Cell-to-cell communication

• Transport of materials

• Coordination between cells

Differences: Cell Wall vs Cell Membrane

NEET Important Points ⭐

• Cell wall is freely permeable

• Present only in plant cells

• Middle lamella = calcium pectate

• Secondary wall contains lignin

• Plasmodesmata connect adjacent cells

Common NEET Traps ⚠️

• ❌ Cell wall is NOT living

• ❌ Animal cells do NOT have cell wall

• ✔ Middle lamella is rich in pectin

• ✔ Cell wall prevents bursting

Quick Revision ⏱️

• Cell wall → Non-living

• Main component → Cellulose

• Middle lamella → Calcium pectate

• Secondary wall → Lignin

• Plasmodesmata → Cell connection

NEET Practice MCQs

Q1. Main component of plant cell wall is:
A) Starch
B) Cellulose
C) Glycogen
D) Chitin

Answer: B

Q2. Middle lamella is rich in:
A) Cellulose
B) Lignin
C) Calcium pectate
D) Protein

Answer: C

Q3. Cell wall is:
A) Selectively permeable
B) Impermeable
C) Freely permeable
D) Semi-permeable

Answer: C

One-Line NEET Takeaway ⭐

The cell wall is a rigid, non-living, freely permeable structure that provides shape, strength, and protection to plant cells.