nutrition/photosyn/systems

• Photosynthesis


  The process where some organisms are able to turn light energy into chemical energy
• Organisms that use photosynthesis to make their own food


  • Producers
• Type of reaction

  Photosynthesis is an endothermic reaction
• Where photosynthesis takes place


  Photosynthesis takes place in the chloroplasts
• Photosynthesis chemical reaction


  Carbon dioxide + Water → Glucose + Oxygen
• Photosynthesischemical equation

  6CO2 + 6H2O → C6H12O6 + 6O2
• As temperature increases

  The rate of photosynthesis increases
• Once the temperature exceeds the optimum

  The rate of photosynthesis decreases as enzymes begin to denature
• As the light intensity increases

  The rate of photosynthesis increases
• Inverse square law

  As the distance from the light source doubles, the light intensity quarters. Light intensity ∝ 1 / distance2
• As the concentration of carbon dioxide increases

  The rate of photosynthesis increases
• Limiting factor


  A factor that limits the rate of a reaction when there is not enough of it
• Leaves are thin which provides a short diffusion distance
• The spongy mesophyll layer has lots of air spaces for efficient gas exchange
• Palisade mesophyll cells have lots of chloroplasts for photosynthesis
• Mineral ions

  Used for growth in plants
• Common ions in plants


  • Magnesium ion (Mg2+)
  • Nitrate ion (NO3-)
• Magnesium ions

  Used in chlorophyll
• Nitrate ions

  Used in amino acids
• The body needs different substances in different proportions to function properly, too much or too little of different things can be harmful
• Groups needed for a balanced diet

  • Carbohydrates
  • Proteins
  • Lipids (fats)
  • Vitamins
  • Minerals
  • Water
  • Dietary fibre
• Carbohydrates


  The body's main source of energy
• Proteins

  Can have structural or metabolic roles in the body and are used as hormones, enzymes, antibodies, etc
• Functions of lipids in the body

  • Energy storage
  • Cell membranes
  • Buoyancy
  • Insulation
• Uses of vitamin A

  • Keeping the skin healthy
  • Improved vision in the dark
  • Strengthening the immune system
• Vitamin C

  Used for growth and repair
• Vitamin D

  Used in the absorption of calcium
• Calcium

  Strengthens bones and teeth
• Iron


  Used in haemoglobin to transport oxygen in the blood
• Uses of water in the body

  • A reaction medium
  • Temperature control
  • Transport
• Dietary fibre

  Helps keep everything flowing through the digestive system
• Water

  Used as a reaction medium, for temperature control, and for transport
• More active people

  Have greater energy requirements
• As we age

  Adults generally require more energy than children
• Alimentary canal

  The complete tube that food passes through as it passes through the body
• Digestive system

  Includes the alimentary canal and digestive glands
• Passage of food through the alimentary canal

  Mouth → oesophagus → stomach → small intestine → large intestine → rectum
• Function of the mouth

  To chew and break down food, and to secrete digestive enzymes
• Function ofOesophagus

  The tube that carries food from the mouth to the stomach
• function od Stomach

  A muscular sac containing acid that pummels the food and breaks it down further