Biology- Yr 8

• Enzymes

  Breaks down large molecules (food) into smaller molecules
• Amylase


  Enzymes within saliva that break down carbs
• Digestive system organs


  • Mouth
  • Liver
  • Pancreas
  • Large intestine
  • Small intestine
  • Stomach
  • Anus
  • Oesophagus
• Ingestion


  Taking in
• Categories of enzymes


  • Carbohydrase (Amylase)
  • Lipase
  • Protease (Pepsin)
• Carbohydrase (Amylase)


  Breaks down starches, found in saliva and pancreas
• Lipase


  Breaks down lipids (fats) into fatty acid and glycerol, found in pancreas, mouth, stomach
• Protease (Pepsin)


  Breaks down proteins, found in stomach, pancreas, small intestine
• Food groups


  • Vitamins (A, D, C)
  • Carbs (Bread)
  • Water
  • Minerals (iron, calcium)
  • Lipids (Fats, Avocado)
  • Protein (Meat)
  • Fibre (beans, broccoli)
• Liver is the biggest organ in the body, produces bile which neutralises acid
• Villi


  Hairlike projections on small intestine that increase surface area for faster diffusion
• Large intestine


  Forms faeces, always wider than small intestine
• Pancreas creates most enzymes
• Tests for food components

  • Iodine solution - test for starches
  • Benedict's solution - test for sugar
  • Biurets solution - test for proteins
  • Ethanol - test for fats
• Practical - Bread


  1. Measure weight

  2. Measure temperature before

  3. Measure temperature after
• Vitamins


  • Vitamin A - Healthy eyes and skin, Deficiency: Xerophthalmia, Symptoms: Night blindness
  • Vitamin B - Healthy nerves, respiration, blood cells, Deficiency: Beriberi, Symptoms: Tingling in hands and feet, problems with balance
  • Vitamin C - Healthy joints and blood vessels, Deficiency: Scurvy, Symptoms: Feeling tired, Red/Blue spots on skin
  • Vitamin D - Helps absorb calcium, keeps bones and teeth strong, Deficiency: Rickets, Symptoms: Weak, bent bones
• Dependent variable


  Variable that you measure
• Independent variable


  Variable that you change
• Enzymes are biological catalysts
• Aerobic Respiration


  Glucose + Oxygen → Carbon dioxide + water + energy
• Aerobic respiration


  With oxygen
• Anaerobic respiration


  Without oxygen
• Why we need energy: Muscle contraction, Maintain body temperature, Growth
• Mitochondria are where most aerobic respiration happens (ATP energy produced)
• All living things must respire
• Anaerobic respiration


  Glucose → Lactic acid
• Anaerobic respiration occurs when oxygen is being used up faster than it is being replaced, causes fatigue and muscle soreness
• Oxygen debt is when your body has run out of O2, you need to regain O2 for energy
• Lactic acid is transported in blood to the liver where it is turned back into glucose, requires oxygen
• Plants photosynthesise during the day, and respire during the day and also the night
• Plant cells respire anaerobically to produce ethanol and carbon dioxide, as well as energy
• Yeast is an important microorganism in food production, used to make bread, beer, vodka and wine through fermentation
• Fermentation


  Glucose → Ethanol (alcohol) + Carbon dioxide + Energy
• Gasohol is a fuel containing a mixture of gasoline and alcohol, mixing alcohol with a fossil fuel makes the non-renewable fossil fuel last longer
• Biogas is a mixture of gases (mainly methane) produced when bacteria break down plant material or human waste, can be burnt as fuel or used to generate electricity
• Biogas generators are used in areas with no electricity, use up plant and animal wastes and the material left can be used for fertiliser
• Variation


  The differences between individual organisms
• Causes of variation


  • Genetic factors
  • Environmental factors
  • Genetic and environmental factors
• Dogs are the same species even though a labrador and poodle look very different, their offspring is fertile
• Species


  A group of similar looking organisms that can breed together to form children (offspring) who can also grow up and have children of their own