Keywords

• Factors that affect health

  • Lifestyle
  • Genetics
  • Stress
• Communicable disease


  Caused by a pathogen, and can be spread
• Non-communicable disease


  Not caused by a pathogen and cannot be spread
• Risk factor


  Factors that increase the risk of suffering from an illness
• Pathogens


  Micro-organisms that cause infectious diseases
• Types of pathogen


  • Fungi
  • Bacteria
  • Viruses
  • Protists
• Bacterial diseases


  Bacteria produce toxins which damage tissues and make you feel ill
• Viral diseases


  Viruses enter living cells and reproduce, causing cell damage
• Malaria is caused by a protist
• Non-specific defence system


  • Skin acts as a barrier, nose, trachea and bronchi prevent entry of pathogens and eject them from the body, stomach contains acid to kill bacteria
• Phagocytes


  Engulf and destroy pathogens during phagocytosis
• Antibodies


  Specific to each pathogen, they attach to pathogens and clump them together to enable them to be destroyed by phagocytes
• Antitoxins


  Break down toxins produced by pathogens
• Vaccine


  A dead or weakened form of the pathogen
• Herd immunity


  A large percentage of the population must be vaccinated to protect those who are not
• Risk factor


  A chemical which causes a change in the body
• Antibiotics are used to kill bacterial pathogens inside the body, but do not work on viruses
• Viruses live inside living cells, so killing the virus without damaging body tissues is difficult
• Digitalis and aspirin


  • Digitalis comes from foxgloves, aspirin comes from willow tree bark
• Drugs are synthesised in a lab and made in factories in the pharmaceutical industry in modern times
• Less chlorophyll, so less photosynthesis, so less glucose production in plants
• Palisade mesophyll


  Where most photosynthesis is carried out in a leaf
• Tissue


  A group of specialised cells that work together to perform a specific function
• Meristem tissue is found at the tips of roots and shoots
• Word equation for photosynthesis

  Carbon dioxide + water -> glucose + oxygen
• Photosynthesis


  An endothermic reaction as it requires light energy, absorbed by chloroplasts in order to happen
• Factors affecting photosynthesis


  • Carbon dioxide concentration
  • Light intensity
  • Temperature
  • Chlorophyll
• Unspecialised plant cells


  Meristematic cells
• A farmer needs to consider factors like carbon dioxide, light, temperature and chlorophyll to maximise photosynthesis and plant growth, while also balancing spending on light and heat in a greenhouse to maximise profit
• Xylem


  Transports water and minerals, cells strengthened by lignin join end to end to form a tube
• Transpiration


  Evaporation of water and loss through stomata of leaf
• Factors affecting transpiration rate

  • Temperature
  • Humidity
  • Light intensity
  • Air movement
• Phloem


  Transports dissolved sugars from leaves to the rest of the plant, cells join to form hollow tubes
• Translocation


  The movement of dissolved sugars through phloem
• Uses of glucose in plants

  • Growth
  • Respiration
  • Oils and fats
  • Proteins
  • Starch
• Testing a leaf for starch

  Use iodine, orange-blue/black
• Testing a leaf for proteins


  Use Biuret solution, blue-purple
• Testing a leaf for glucose

  Use Benedicts solution, blue-orange