Organisation in animals

• What are the five levels of organization in biological systems?

  Cells, tissues, organs, organ systems, organism
• What is a tissue?


  A group of cells with similar structures to perform a specific function
• What is an organ?


  A group of tissues working together to perform a specific function
• What is the function of the liver in digestion?


  Produces bile, which neutralizes hydrochloric acid and emulsifies fat
• What is the function of saliva in digestion?


  Lubrication to help swallowing and contains amylase to break down starch
• Name three enzymes produced in the pancreas.


  Amylase, protease, lipase
• What are the four main components of blood?

  Red blood cells, white blood cells, plasma, platelets
• What is the function of platelets?


  Form blood clots to prevent blood loss and stop infections
• Describe three adaptations of a red blood cell.


  Bi-concave disc shape, contains haemoglobin, no nucleus
• How do white blood cells protect the body?


  They engulf pathogens and produce antitoxins or antibodies
• Name the substances transported in the blood plasma.

  Hormones, proteins, urea, carbon dioxide, glucose
• Why is the human circulatory system a double circulatory system?


  Blood passes through the heart twice for every circulation around the body
• How does the structure of an artery relate to its function?


  It carries blood away from the heart under high pressure with a small lumen and thick, elasticated walls
• How does the structure of a vein relate to its function?


  It carries blood back to the heart at low pressure and has valves to prevent backflow
• How does the structure of a capillary relate to its function?

  It has a one cell thick wall to provide a short diffusion distance
• What structures does air pass through when breathing in?

  • Mouth/nose
  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli