Tissues in Action
Tissues and the division of labour
Find out why groups of cells share out the work as tissues.
You began life as one cell. It divided again and again, and the new cells took on different jobs: some became skin (protection), some muscle (movement), some bone (support), some nerves (control).
Remember the ladder from Chapter 2:
- similar cells form a tissue;
- tissues form an organ;
- organs form an organ system;
- organ systems form an organism (a whole living thing).
A tissue is a group of cells that look alike and work together for one job.
"Why not let every cell do everything?" Think of a school. One person can't teach, cook lunch, drive the bus and clean. Each person has one job, and the school runs well. In the body this is called division of labour, and it makes the body efficient.
- An amoeba is one cell, so that one cell does everything.
- In a plant or animal, muscle moves, nerves carry messages, xylem carries water and minerals, phloem carries food.
"Why are plant tissues different from animal tissues?"
| Plants | Animals |
|---|---|
| Stay in one place, so need support: their cell walls make them rigid | Most move about (sponges are an exception), so their cells are flexible |
| Have tissues to catch sunlight and make food (photosynthesis) | Have tissues to digest food they eat |
| Keep growing from special growing tissues | Grow differently, and move things around the body in other ways |
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