2.1 Principles of organisation

• 1. Cell - smallest structural and functional unit of an organism, eg. muscle cell
  2. Tissue - group of cells with a similar structure and function, eg. muscle tissue
  3. Organ - aggregation (group) of tissues performing specific functions, eg. stomach
  4. Organ system - group of organs performing specific functions, eg. digestive system
• Rewrite these in the correct order, from smallest to largest: brain, neurone, dog, nervous system, nerve. (1) Neurone (cell) → nerve (tissue) → brain (organ) → nervous system (organ system) → dog (organism
• why is this statement wrong?

  “The nucleus of a cell is an organ.”

  The nucleus is a sub-cellular structure (an organelle), not an organ
• why is this statement wrong?

  “Food passes through the liver and pancreas in the digestive system.”

  These organs can be thought of as ‘accessory organs’. Food does not pass through them, but they make substances (eg. bile and enzymes) that are released into the small intestine.