Biology: Topic 3+ 4

• Communicable diseases


  • Bacteria
  • Fungi
  • Virus
• Bacteria


  • Can be spread by air, direct contact
• Bacteria


  • Salmonella
  • Malaria
• Fungi


  • Athlete's Foot
• Virus


  • TMV
• Preventing communicable diseases


  1. Staying hygienic

  2. Washing hands

  3. Self-isolation

  4. Vaccination
• If you get a disease, your body has many ways of fighting against it
• Three main lines of defense


  • Skin
  • Mucus
  • Lymphocytes
• Lymphocytes make antibodies and memory cells
• Second line of defense


  • Phagocytes
  • Stomach acid
  • Lysozymes
• Antibodies are part of the immune response
• Aerobic respiration


  1. Glucose

  2. Oxygen

  3. Water

  4. Carbon dioxide
• During exercise


  Heart and breathing rate increase to supply more oxygen and glucose to muscles
• Respiration provides energy for chemical reactions, warmth, and movement
• Anaerobic respiration


  1. Glucose

  2. Lactic acid
• Lactic acid is broken down by the liver using oxygen
• Anaerobic respiration in plants


  1. Glucose

  2. Ethanol

  3. Carbon dioxide
• Metabolism


  The sum of all chemical reactions in a cell/organism
• Metabolic processes


  • Glucose to starch, glycogen & cellulose
  • Fatty acids to lipids (fat)
  • Respiration
  • Breakdown of excess proteins
• Xylem transports water from roots up the plant for transpiration
• Phloem transports food up and down the plant through translocation
• the endocrine system is made up of glands that secrete hormones into the bloodstream
• Pathogen


  A micro-organism that causes disease
• Types of pathogens


  • Bacteria
  • Viruses
  • Fungi
  • Protists
• Viruses reproduce


  1. Inserting genes into cells

  2. Causing cells to produce more copies
• Viruses


  • Measles (rash, spread by droplets)
  • HIV (an STD/STI that causes AIDS compromised immune system)
• Bacteria


  Release toxins into your body that damage cells
• Bacteria


  • Salmonella (undercooked food, food poisoning)
  • Gonorrhoea (STD, causes yellow discharge)
• Fungi


  Damage cells
• Protists


  Single-celled organisms
• Protist disease


  • Malaria (caused by a protist that infects red blood cells)
• Plant diseases


  • Rose black spot (fungus, causes leaves to fall off)
  • Tobacco mosaic virus (discolours leaves, less chlorophyll, stunted growth)
• Skin stops, mucus in nose/traches traps, acid & enzymes kill pathogens
• Plant defences


  • Cell wall
  • Waxy cuticle
  • Bark are barriers
  • Antibacterial chemicals
  • Poison/thorns to deter other organisms
• Antigen


  A substance that triggers the immune response
• Lymphocytes


  A type of white blood cell that produces antitoxins and antibodies
• Antitoxins


  Neutralise toxins made by pathogens
• Antibodies


  Bind to the antigen of a pathogen, stop viruses from infecting cells, and cause them to clump together
• T cells


  Store antibodies in lymph nodes, ready for next time (immunity)
• Phagocytes


  Another type of white blood cell that ingests pathogens