CLASS 8 SCIENCE
COMPLETE REVISION NOTES
Chapter 1
THE INVISIBLE LIVING WORLD – CELLS
What’s Included?
✔ What Are Living Things Made Up Of?
✔ Types of Organisms
✔ Discovery of the Cell
✔ Cell Theory
✔ Basic Structure of a Cell
✔ Cell Organelles and Their Functions
✔ Plant Cell vs Animal Cell
✔ Specialised Cells
✔ Variation in Cell Size
✔ Growth and Division of Cells
✔ Levels of Organisation in Living Organisms
✔ Quick Revision Notes
CBSE Class 8 Science
Complete Study & Revision Notes
Well-Organized Notes with Diagrams & Tables
For Educational Purposes Only
Version 1.0
Class 8 Science - Revision Notes 1
, Class 8 Science – Revision Notes
Chapter 1: The Invisible Living World – Cells
1. What Are Living Things Made Up Of?
Key Concept
Just like a building is made up of bricks, living organisms are made up of tiny units called
cells. A cell is the basic structural and functional unit of life.
2. Types of Organisms
Unicellular Organisms
• These organisms are made up of a single cell.
• They are microscopic and cannot be seen with the naked eye.
Examples: Bacteria, Amoeba, Paramecium, and Yeast.
Multicellular Organisms
• These organisms are made up of many cells.
• Different cells work together to perform various functions.
Examples: Humans, Animals, Birds, Trees, and Plants.
3. Discovery of the Cell
• Cells were first discovered by Robert Hooke in 1665.
• He observed a thin slice of cork under a microscope.
Class 8 Science - Revision Notes 2
COMPLETE REVISION NOTES
Chapter 1
THE INVISIBLE LIVING WORLD – CELLS
What’s Included?
✔ What Are Living Things Made Up Of?
✔ Types of Organisms
✔ Discovery of the Cell
✔ Cell Theory
✔ Basic Structure of a Cell
✔ Cell Organelles and Their Functions
✔ Plant Cell vs Animal Cell
✔ Specialised Cells
✔ Variation in Cell Size
✔ Growth and Division of Cells
✔ Levels of Organisation in Living Organisms
✔ Quick Revision Notes
CBSE Class 8 Science
Complete Study & Revision Notes
Well-Organized Notes with Diagrams & Tables
For Educational Purposes Only
Version 1.0
Class 8 Science - Revision Notes 1
, Class 8 Science – Revision Notes
Chapter 1: The Invisible Living World – Cells
1. What Are Living Things Made Up Of?
Key Concept
Just like a building is made up of bricks, living organisms are made up of tiny units called
cells. A cell is the basic structural and functional unit of life.
2. Types of Organisms
Unicellular Organisms
• These organisms are made up of a single cell.
• They are microscopic and cannot be seen with the naked eye.
Examples: Bacteria, Amoeba, Paramecium, and Yeast.
Multicellular Organisms
• These organisms are made up of many cells.
• Different cells work together to perform various functions.
Examples: Humans, Animals, Birds, Trees, and Plants.
3. Discovery of the Cell
• Cells were first discovered by Robert Hooke in 1665.
• He observed a thin slice of cork under a microscope.
Class 8 Science - Revision Notes 2
