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Levels of organisation and cell structure
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Living things are built in levels, from tiny organelles to whole systems.
From organelles to systems
Organelles are structures inside cells, such as the nucleus or mitochondria.
Cells are the basic units of life.
A tissue is a group of similar cells working together to do a particular job.
An organ is made of several tissues working together.
An organ system is a group of organs working together.
Cells are the basic units of life.
A tissue is a group of similar cells working together to do a particular job.
An organ is made of several tissues working together.
An organ system is a group of organs working together.
Examples
Plant and animal cells compared
Both have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.
Only plant cells have a cellulose cell wall, chloroplasts and a large permanent vacuole containing cell sap.
Not every plant cell has chloroplasts: root cells, for example, are underground and do not photosynthesise.
Only plant cells have a cellulose cell wall, chloroplasts and a large permanent vacuole containing cell sap.
Not every plant cell has chloroplasts: root cells, for example, are underground and do not photosynthesise.
Put these in order from smallest to largest: organ, cell, organelle, system, tissue.
- Organelles are inside cells.
- Similar cells form tissues, tissues form organs, and organs form systems.
Answer: organelle, cell, tissue, organ, system
Organelles make up cells, similar cells make tissues, tissues make organs and organs make systems. Plant cells have a cell wall, chloroplasts and a large vacuole as well as the structures animal cells have.
The interactive lesson includes the diagrams for this topic.
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