Levels of organisation

• What is the basic building block of all living organisms?


  Cells
• What is the difference between unicellular and multicellular organisms?


  Unicellular organisms consist of one cell, while multicellular organisms are made of multiple cells.
• What are organelles? Name three examples.


  Organelles are structures within cells. Examples include the nucleus, mitochondria, and ribosomes.
• In multicellular organisms, what do specialized cells form?


  Specialized cells form tissues.
• What is the hierarchy of organization in multicellular organisms from smallest to largest?


  Cells → Tissues → Organs → Organ Systems.
• What is an organ system?


  An organ system is a group of organs that work together to perform specific functions.
• Give an example of an organ system in animals.

  The digestive system.
• Give an example of an organ system in plants.

  The vascular system.