Cell organisation and diffusion

In a nutshell

Cells are organised in a particular way to make up multicellular organisms. The cells form tissues and the tissues form organs. The organs then form organ systems and a multicellular organism is made from several organ systems. 

Cell organisation

Multicellular organisms are made up of lots of cells. These are organised into groups. 

Example

Diffusion

Cells need to use glucose and oxygen to survive. They also need to get rid of their waste products like carbon dioxide. These are small molecules so they can diffuse in and out of cells. Diffusion is where a substance moves from an area of high concentration to an area of low concentration. 

Example

Below shows a partially permeable membrane (1.) which separates the outside of the cell (A) and the inside of the cell (B). The orange circles (2.) represent glucose molecules. There are more glucose molecules outside of the cell, therefore, there is a greater concentration of glucose outside of the cell. The glucose will then diffuse down the concentration gradient into the cell.