From cell to organism
Build a living body, level by level.
A wall is made of bricks
A wall is built from bricks. A living body is built from cells. But a body is not just a heap of cells.
What do you think a body does with its cells?
What this lesson covers
The idea
Similar cells form a tissue, different tissues form an organ, organs working together form an organ system, and all organ systems make up an organism: Cell → Tissue → Organ → Organ system → Organism.
A wall is made of bricks
A wall is built from bricks. A living body is built from cells. But a body is not just a heap of cells.
What do you think a body does with its cells?
- It groups them into bigger and bigger parts, level by level
- It keeps them all mixed in one big heap
- Every cell works completely alone
Build a body, level by level
Start with loose cells from the stomach. Tap pieces that belong together, then press the button. Keep going up the levels.
Cell → Tissue → Organ → Organ system → Organism
Cell is the basic unit of life, just like a brick is the basic unit of a wall. A group of similar cells forms a tissue. Different tissues organised together form an organ. Several organs working together form an organ system that performs a major function of the body. All the organ systems together make up a complete organism.
- Level | What it is
- Cell | The basic unit of life: a muscle cell, a lining cell
- Tissue | A group of similar cells: muscle tissue, lining tissue
- Organ | Different tissues organised together: the stomach
- Organ system | Several organs working together: the digestive system
- Organism | All the organ systems together: a plant or an animal
Notes
Similar cells form a tissue, different tissues form an organ, organs working together form an organ system, and all organ systems make up an organism. Cell → Tissue → Organ → Organ system → Organism
Check yourself
A group of similar cells forms a:
Muscle tissue and lining tissue are different tissues. Organised together, they form the stomach. What is the stomach?
Which is the right order, from the smallest level to the biggest?
How many levels of organisation are there from a cell up to an organism? Count both the first and the last.
Answer: 5
Cell, tissue, organ, organ system, organism: 5 levels.
- Organ. An organ is made of different tissues, so it is a bigger level than a tissue.
- Tissue — correct. Yes. A group of similar cells forms a tissue.
- Organ system. An organ system is made of several organs, so it is much bigger.
- A tissue. A tissue is a group of similar cells. The stomach is made of different tissues.
- An organ system. An organ system is made of several organs working together. The stomach is just one organ.
- An organ — correct. Yes. Different tissues organised together form an organ.
- Cell → Tissue → Organ → Organ system → Organism — correct. Yes. Each level is made of the one before it.
- Cell → Organ → Tissue → Organ system → Organism. An organ is made of different tissues, so a tissue comes before an organ.
- Tissue → Cell → Organ → Organism → Organ system. The cell is the basic unit, so it comes first. The organism, made of all the organ systems, comes last.