🌿 CLASS 9 BIOLOGY NOTES
CHAPTER: THE FUNDAMENTAL UNIT OF LIFE (CELL)
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🧫 INTRODUCTION
All living organisms are made up of tiny units called cells.
👉 Cell is the basic structural and functional unit of life.
🔬 Robert Hooke discovered cells in 1665 while observing cork under a
microscope.
He saw small box-like compartments and named them cells.
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🧠 CELL THEORY
Given by:
- Schleiden
- Schwann
Modified by:
- Virchow
Main Points:
1. All living organisms are made up of cells.
2. Cell is the basic unit of life.
3. New cells arise from pre-existing cells.
⭐ “Omnis cellula e cellula”
➡️Means: Every cell comes from another cell.
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🔍 TYPES OF ORGANISMS
1. Unicellular Organisms
, Made up of only one cell.
Examples:
- Amoeba
- Paramecium
- Bacteria
2. Multicellular Organisms
Made up of many cells.
Examples:
- Humans
- Plants
- Animals
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📏 CELL SIZE AND SHAPE
- Cells can be different in size and shape.
- Shape depends on function.
Examples:
Cell| Shape
Nerve cell| Long and branched
RBC| Circular
Muscle cell| Spindle shaped
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🧬 BASIC STRUCTURE OF CELL
A cell has 3 main parts:
1. Cell membrane
2. Cytoplasm
3. Nucleus
---
CHAPTER: THE FUNDAMENTAL UNIT OF LIFE (CELL)
---
🧫 INTRODUCTION
All living organisms are made up of tiny units called cells.
👉 Cell is the basic structural and functional unit of life.
🔬 Robert Hooke discovered cells in 1665 while observing cork under a
microscope.
He saw small box-like compartments and named them cells.
---
🧠 CELL THEORY
Given by:
- Schleiden
- Schwann
Modified by:
- Virchow
Main Points:
1. All living organisms are made up of cells.
2. Cell is the basic unit of life.
3. New cells arise from pre-existing cells.
⭐ “Omnis cellula e cellula”
➡️Means: Every cell comes from another cell.
---
🔍 TYPES OF ORGANISMS
1. Unicellular Organisms
, Made up of only one cell.
Examples:
- Amoeba
- Paramecium
- Bacteria
2. Multicellular Organisms
Made up of many cells.
Examples:
- Humans
- Plants
- Animals
---
📏 CELL SIZE AND SHAPE
- Cells can be different in size and shape.
- Shape depends on function.
Examples:
Cell| Shape
Nerve cell| Long and branched
RBC| Circular
Muscle cell| Spindle shaped
---
🧬 BASIC STRUCTURE OF CELL
A cell has 3 main parts:
1. Cell membrane
2. Cytoplasm
3. Nucleus
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