Communicable Diseases

• What are the main disease-causing pathogens in humans?

  Bacteria and viruses
• How do bacteria and viruses differ in structure?

  Bacteria are prokaryotic; viruses are not cells
• What form does bacterial genetic information take?

  Circular strand of DNA
• Why do bacteria not require a host to survive?

  They can live independently
• What is the size comparison between bacteria and viruses?

  Viruses are significantly smaller than bacteria
• What structures do bacteria possess that viruses do not?

  Cell membrane, cell wall, cytoplasm, organelles
• What bacterium causes tuberculosis (TB)?

  Mycobacterium tuberculosis
• How does TB initially affect the body?

  First infection is symptomless
• What happens to TB bacteria when the immune system weakens?

  They become active and destroy lung tissue
• What are the symptoms of active TB?

  Breathing problems, coughing, weight loss, fever
• What can meningitis be caused by?

  Bacterial infection of the meninges
• What virus causes AIDS?

  Human Immunodeficiency Virus (HIV)
• What are the first symptoms of HIV?

  Fevers, tiredness, and headaches
• What happens after several weeks of HIV infection?

  HIV antibodies appear in blood
• What leads to the development of AIDS from HIV?

  Weakening of the immune system
• What does the influenza virus infect?

  Ciliated epithelial cells of the gas exchange system
• What is Athlete's foot caused by?

  A fungus
• How is Athlete's foot spread?

  Direct contact with spores
• What is malaria transmitted by?

  Female Anopheles mosquito
• What virus infects tobacco plants?

  Tobacco mosaic virus
• What are the physical barriers of pathogen entry in plants?

  Cellulose cell walls, lignin layer, waxy cuticles
• What happens when a pathogen is detected in plants?

  Various mechanisms are activated to prevent spread
• What is necrosis in plants?

  Cells near infection are killed
• What are menthols produced by mint classified as?

  Terpenoids
• What is the role of lysozyme in animals?

  Kills bacterial cells by damaging cell walls
• What is the function of interferons?

  Prevent viruses from spreading to uninfected cells
• What is phagocytosis?

  Process where white blood cells engulf pathogens
• What do blood clots do?

  Reduce blood loss and seal openings
• What are memory cells in the immune system?

  Cells that replicate when exposed to pathogens
• Where do B cells mature?

  In the bone marrow
• What is the role of T helper cells?

  Stimulate B cells and T killer cells to divide
• What are antibodies?

  Globular protein molecules produced by lymphocytes
• What is the function of antibodies?

  Attach to antigens and inhibit their action

  
• What are the components of antibodies?

  Four polypeptide chains linked by disulphide bridges
• What is the constant region of an antibody responsible for?

  Phagocyte interaction to stimulate phagocytosis
• How does the variable region of an antibody differ?

  It varies for each type of antibody
• What is active immunity?

  Production of antibodies in response to an antigen

  
• What is natural passive immunity?

  Antibodies crossing from mother to child
• What is the difference between bactericidal and bacteriostatic antibiotics?

  Bactericidal kill bacteria; bacteriostatic inhibit growth
• How do bacteria develop antibiotic resistance?

  Through natural selection of resistant bacteria