1. National 5
Cells, Tissues & Organs
Mr G Davidson

2. Levels of Organisation
All organisms have different levels of organisation so that they function properly.
Unicellular organisms can lead an independent life even though they are only one cell.
Multicellular organisms, however, contain a huge number of cells.
Friday, November 16, 2018
Mr G Davidson

3. Levels of Organisation
These cells are initially all the same.
Eventually they will become specialised and this means they will develop into a special shape or develop a special structure which allows them to perform a specific task.
Friday, November 16, 2018
Mr G Davidson

4. Levels of Organisation
These cells are then divided into groups to do specific jobs and we call these groups tissues.
e.g. muscle cells are grouped to form muscle tissue, red blood cells and white blood cells to form blood tissue, sieve tubes and companion cells to form phloem tissue, etc.
Friday, November 16, 2018
Mr G Davidson

5. Levels of Organisation
If we group a number of tissues together to perform a particular function, we call it an organ.
e.g. in plants the vascular bundles are organs and are made up of phloem tissue and xylem tissue.
in animals the heart is an organ made up of muscle tissue, blood tissue, etc.
Friday, November 16, 2018
Mr G Davidson

6. Levels of Organisation
If we group a number of organs together to perform a particular function, we call it a system.
in animals the circulatory system is made up of the heart, blood, arteries, veins, etc.
If we group all the systems together, we make up the whole organism.
Friday, November 16, 2018
Mr G Davidson

7. Levels of Organisation
Cells
Tissues
Organs
Systems
Organism
Friday, November 16, 2018
Mr G Davidson

8. Levels of Organisation
Friday, November 16, 2018
Mr G Davidson