Cell

A cell is the smallest part of a living thing that can carry out all life processes.

• Why it is called the “basic unit of life”: A cell can take in nutrients, use energy, remove wastes, grow, and make new cells by dividing.
• Different shapes for different jobs: Cells are not all alike—muscle cells are shaped to help in movement, and nerve cells are long so they can carry messages quickly.
• What’s inside a cell (simple idea): Most cells have a thin outer covering called the cell membrane, a jelly-like inside called cytoplasm, and a control centre called the nucleus (in many cells).
• One cell vs many cells: Some organisms are unicellular (made of one cell, like Amoeba), while humans and plants are multicellular (made of many cells that share work).
• How cells build the body: Cells join to form tissues, tissues form organs, and organs work together in organ systems—like bricks forming bigger structures.
• A useful nuance: An egg is a single cell, but it can be very large because it stores food and materials needed for early development (like the yolk in bird eggs).