biology paper 1

• Main groups of nutrients needed

  • Carbohydrates (like starch and glucose)
  • Proteins
  • Fats
• Role of digestion


  To break all this food down into tiny pieces so that we can absorb it into our body cells
• Digestion process


  1. Physical breakdown (chewing)

  2. Chemical breakdown by enzymes
• Mouth


  1. Chew food

  2. Release saliva from salivary glands

  3. Saliva contains salivary amylase to break down carbohydrates
• Esophagus


  Food passes down
• Stomach


  1. Contracts muscular walls to push and mix food

  2. Produces pepsin enzyme to break down proteins

  3. Produces hydrochloric acid to kill bacteria and provide right environment for pepsin
• Small intestine


  1. Digested food absorbed into bloodstream

  2. Produces digestive enzymes

  3. Pancreas produces and pushes digestive enzymes into small intestine

  4. Gallbladder releases bile to neutralize acid and emulsify fats
• Lining of small intestine

  • Villi (finger-like projections) to increase surface area
  • Single layer of surface cells for short diffusion distance
  • Good blood supply to maintain concentration gradient
• Large intestine


  1. Absorbs excess water from leftover material

  2. Stores feces in rectum
• Recap of full digestive process

  Food in mouth - chewed and mixed with saliva

  2. Swallowed down esophagus into stomach

  3. Stomach mixes and breaks down food

  4. Passed to small intestine, mixed with pancreatic juices and bile

  5. Nutrients absorbed into bloodstream

  6. Leftover material passes to large intestine, water absorbed, feces stored in rectum