Edexcel A Level (IAL) Biology -3.1 Cell Theory- Study Notes- New Syllabus
Edexcel A Level (IAL) Biology -3.1 Cell Theory- Study Notes- New syllabus
Edexcel A Level (IAL) Biology -3.1 Cell Theory- Study Notes -Edexcel A level Biology – per latest Syllabus.
Key Concepts:
- 3.1 know that all living organisms are made of cells, sharing some common features
All Living Organisms Are Made of Cells
🌱 Introduction
The cell is the basic structural and functional unit of life.
Every living organism from the tiniest bacterium to the largest tree or animal is made up of one or more cells.
This idea forms the basis of the Cell Theory.
📘 Cell Theory (Summary)
- All living things are made of one or more cells.
- The cell is the basic unit of structure and function in living organisms.
- All cells arise from pre-existing cells.
- Proposed by Schleiden (plants) and Schwann (animals), later refined by Virchow.
🧩 Common Features Shared by All Cells
| Feature | Description | Function |
|---|---|---|
| Cell membrane (Plasma membrane) | Thin, flexible boundary surrounding the cell | Controls movement of substances in & out |
| Cytoplasm | Jelly-like fluid inside the cell | Site for many chemical reactions |
| Genetic material (DNA/RNA) | Carries genetic information | Controls cell’s activities & reproduction |
| Ribosomes | Small structures in cytoplasm | Site of protein synthesis |
| Enzymes | Biological catalysts | Speed up metabolic reactions |
| Energy release system | Cellular respiration (in cytoplasm or mitochondria) | Produces energy (ATP) for cell activities |
🔬 Types of Organisms Based on Cells
| Type | Example | Description |
|---|---|---|
| Unicellular | Amoeba, Bacteria, Yeast | Made of one single cell that carries out all life processes |
| Multicellular | Humans, Plants, Fungi | Made of many specialized cells working together |
⚙️ Why Cells Are So Important
- They form tissues, which form organs and organ systems.
- They carry out all vital functions: growth, repair, energy production, and reproduction.
- All biochemical reactions occur inside cells.
🧠 Quick Recap
Definition → Cell = smallest unit of life
Cell theory → All living things made of cells; cells arise from pre-existing cells
Shared features → Cell membrane, cytoplasm, DNA/RNA, ribosomes, enzymes
Types → Unicellular (one cell) / Multicellular (many cells)
Importance → Basic building blocks of all organisms