AQA Biology 4.2.1
Principles of organisation
Cells make tissues, tissues make organs, organs make systems. Place real examples on the ladder, then compare how big each level is.
Combined Science · Higher tier
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Bricks and rooms.
A house is made of bricks. Bricks make walls, walls make rooms, and rooms together make the house. Your body is built up in levels too.
If you had to guess, is your stomach one single part, or many different parts working together?
Five levels
Cell, tissue, organ, organ system, organism.
Cells are the basic building blocks of all living organisms. A tissue is a group of cells with a similar structure and function. Organs are groups of tissues performing a specific function. Organs are organised into organ systems, which work together to form organisms. Place each example on its level.
Example 1 of 7
A palisade cell
Size and scale
Each level is many times bigger.
To compare two sizes, divide the bigger by the smaller. They must be in the same unit first. Typical sizes: a cell about 50 µm; a layer of tissue about 1 mm; an organ a few cm; a human about 1.5 m.
1 mm = 1000 µm
1 cm = 10 mm
1 m = 100 cm
times bigger = bigger size ÷ smaller size
This is a comparison by division, not an AQA equation, so it has no triangle.
Think again · is muscle an organ?
“Muscle is an organ.”
Your call
ChooseMuscle is a group of muscle cells that contract together. What level is it?
Sort
Three tissues, one organ
The stomach is an organ. Place each job with the tissue that does it.
Tap a card, then tap the box it belongs in. Tap a placed card to take it back.
Command words in this lesson
- Define
- Each level in the spec’s words.
- Identify
- Which level an example is, and why.
- Calculate
- Same unit, then bigger ÷ smaller.
Key fact
Cells form tissues, tissues form organs, organs form organ systems, and organ systems work together to form an organism.
Key note · AQA 4.2.1
Principles of organisation
- Cells are the basic building blocks of all living organisms.
- A tissue is a group of cells with a similar structure and function.
- Organs are groups of tissues performing a specific function, e.g. the stomach: muscle, glandular and epithelial tissue.
- Organs are organised into organ systems, which work together to form organisms.
- Each level is many times bigger: convert to one unit, then bigger ÷ smaller.
Photograph this card. Tomorrow, cover it and say each line first.
Previous and next
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Not sure whether something is a tissue or an organ?
Sizes are typical round figures. The ladder figure is not to scale; the size strip shows the order of each level.