Cell Theory (NEET Biology)

Chapter: Cell: The Unit of Life
Unit: Cell Biology
Exam Focus: NEET (Concept Clarity + Quick Revision)

What is Cell Theory?

Cell Theory states that all living organisms are made up of cells, and the cell is the basic structural and functional unit of life.
It also states that new cells arise from pre-existing cells through cell division.

This theory forms the foundation of modern biology.

Scientists Involved in Cell Theory

➡️ Final cell theory = Schleiden + Schwann + Virchow

Postulates of Cell Theory

1. All living organisms are composed of one or more cells.

2. The cell is the basic structural and functional unit of life.

3. New cells arise from pre-existing cells by cell division.

Modern Cell Theory (Important for NEET)

• Cells contain genetic material (DNA).

• Metabolic activities occur within cells.

• Cells have similar chemical composition.

• Energy flow takes place within cells.

Importance of Cell Theory

• Explains growth and development of organisms

• Explains repair and regeneration

• Forms the basis of genetics, molecular biology, and physiology

Exceptions to Cell Theory (NEET Traps)

• Viruses are acellular → cell theory does not apply

• Cell theory does not explain origin of the first cell

• Mammalian RBCs lack nucleus but are still cells

Quick Revision (NEET Last-Minute)

• Cell = basic unit of life

• Proposed by Schleiden & Schwann

• Modified by Virchow

• “Omnis cellula e cellula”

• Viruses are exceptions

NEET Practice MCQs

1. Who proposed that new cells arise from pre-existing cells?
A. Hooke
B. Schleiden
C. Schwann
D. Virchow

Answer: D

2. Cell theory does not apply to:
A. Bacteria
B. Amoeba
C. Virus
D. Plant cell

Answer: C

3. ‘Omnis cellula e cellula’ means:
A. Cells contain DNA
B. Cell is basic unit
C. Cells arise from pre-existing cells
D. Cells perform metabolism

Answer: C

Cell Theory – NEET Biology PDF