digestive system

• Protein food test

  Biuret solution

  Blue to purple
• Sugar food test

  Benedict's solution and hot water bath

  Blue to a scale of green to red depending on concentration
• Starch food test

  Iodine (orange to blue-black)
• Lipids food test

  ethanol

  Colourless to cloudy
• Lipids are used for


  long term energy and insulation
• Carbohydrates (starch and sugar) are used for

  Energy
• Protein is used for

  growth and repair
• What are lipids broken down into

  fatty acids and glycerol
• What is protein broken down into

  amino acids
• What is starch broken down into?

  glucose
• What is digestion?

  large food molecules are broken down to smaller molecules which are absorbed into bloodstream
• How long is the digestive system from beginning to end?

  6-9 metres
• How is anus adapted

  Control muscles which open and close it
• Anus


  Waste excreted
• How is large intestine adapted

  Contains millions of bacteria which break down undigested food
• How is the small intestine adapted for absorption?

  Villi
• small intestine


  Enzymes finish breaking down most food

  Food absorbed through walls of bloodstream
• How is stomach adapted

  Acid kills bacteria

  Walls lined with mucus to protect from acid

  Enzymes break down food
• Stomach


  Food churned up with acid and enzymes and releases hydrochloric acid which kills pathogens
• How is oesophagus adapted

  Stretchy and muscular to push food down
• Oesophagus


  Food pushed down into stomach
• How is mouth adapted

  Teeth for breaking down food

  Enzymes in saliva to break down starch
• Mouth


  Food chewed by teeth and mixed with saliva
• Tissues in stomach

  muscular to churn up contents, glandular to produce digestive juices, epithelial to cover and protect outside of the stomach
• epithelial tissue


  A protective body tissue that covers the surfaces of the body, inside and out
• glandular tissue


  Able to produce and release substance such as enzymes and hormones
• How is muscular tissue adapted

  Can contract to bring about movement
• Levels of organization

  organelle, cell, tissue, organ, organ system, organism
• tissue

  A group or layer of cells with a similar structure that work together to perform a specific function
• organ

  A collection of tissues forming a structure which performs a specific function
• Organ system

  Group of organs working together to perform a specific function e.g respiratory system
• Pancreas


  makes enzymes: amylase, lipase and protease
• Gall bladder


  Stores bile
• what does amylase break down

  Starch -> glucose
• what does protease break down

  Proteins -> amino acids
• What does lipase break down

  Lipids -> fatty acids and glycerol
• Large intestine

  Absorbs water from undigested food and forms feces
• Carbohydrates

  • contain carbon, hydrogen and oxygen
  • found in bread, potatoes, rice and pasta
  • the glucose is used for cellular respiration
• Lipids - energy store

  • solid fats and liquid oils
  • important in cell membranes, as hormones and in the nervous system
  • also made from carbon, hydrogen and oxygen
  • insoluble in water
  • found in olive oil, corn oil, butter, cream, cheese
• lipids structure

  3 fatty acids joined to glycerol