- All living organisms are made of cells.
- Unicellular organisms: A single cell performs all basic functions (e.g., Amoeba).
- Movement, intake of food, gaseous exchange, and excretion.
- Multicellular organisms: Consist of millions of specialized cells.
- Different groups of cells perform specific functions efficiently.
- Human beings:
- Muscle cells: Contract and relax to cause movement.
- Nerve cells: Carry messages.
- Blood: Transports oxygen, food, hormones, and waste.
- Plants: Vascular tissues conduct food and water throughout the plant.
- Division of labour: Specialized cells are grouped together for specific functions.
- Tissues: A cluster of similar cells working together for a particular function.
- Examples of tissues: Blood, phloem, muscle.