Levels

• 1. Cells


  the smallest unit of an organism.
• 2. Tissues 


  a group of cells with a similar structure and function, which all work together to do a particular job.
• 3. Organs


  Made from a group of different tissues, which all work together to do a particular job.
• 4. Organ system


  Made from a group of different organs, which all work together to do a particular jobs.
• 5. Organism


  An individual plant, animal or single-celled organism.
• 1. Cell
  2. tissue
  3. organ
  4. organ system
  5. organism
• The cell is the basic structural and functional unit of life. All living things are made up of one or more cells. Cells can exist as independent units (e.g. bacteria) or they may be specialised to form tissues that make up larger structures such as plants and animals.
• Tissues are groups of cells that have a common origin, structure and function. They are often classified according to their shape into epithelial tissue, connective tissue and muscle tissue.
• Organs are composed of two or more types of tissue working together to perform specific functions. For example, the stomach contains both glandular epithelium and smooth muscle tissue.