Communicable disease

• What are the four types of micro-organisms?

  • Bacteria
  • Virus
  • Fungi
  • Protists
• What are some features of bacteria?

  • Very small in shape (tube/spherical shaped)
  • No distinct nucleus
  • Can produce rapidly wherever
  • Can produce poisons
  • Easily eradicated with antibiotics or by the body
• What are some feautures of virus?

  • Vary in shape
  • Smallest of micro-organisms
  • Border living/ non-living
  • Have to be inside in cell to reproduce
  • Break cells open
• What are some features of fungi?

  • Produce external symptoms
  • Tend to be largest of microorganism
  • 'Plant like' cells
  • Reproduce asexually
• What are some features of protists?

  • Mostly unicellular
  • Can be neutrophic or autrophic
  • Most live in water
  • All eukaryote
  • Feed on the cell contents as they grow
• What are some plant defences?

  • Waxy cuticles - provides physical barrier against pathogens
  • Cell wall - physical barrier
  • Production of cellulose - makes it hard for pathogens to enter
• What some risk factors of communicable diseases in plants?


  • Overcrowding
  • Crop variety
  • Mineral nutrition
  • Climate change
• What are the two defence mechanisms?

  • Non-specific
  • Specific
• Whats a non-specific defence mechanism?

  • Act quickly to defend the body but respond in the same way for all pathogens
• What is a specific defence mechanism?

  • Slower to defend the body but produce a specific response for each pathogen
• What are antigens?

  • Unique molecules that can be found on the surface of the cells
• What do the antigens do?


  • allow the immune system to distinguish between the body's own cells (self) and foreign cells (non-self)
  • Any foreign cells can then be destroyed whilst leaving the body's own cells unaffected
• What cells do the antigens allow to identify?

  • Pathogens
  • Toxins
  • Abnormal body cells
• What are the two types of phagocytes and what do they do?

  • Neutrophils = Rapidly engulf and destroy pathogen at site of infection
  • Macrophages = These engulf and digest pathogens but also present the pathogen's antigens on its cell surface to activate other cells in the immune system.
• What happens before phagocytosis?

  • Chemotaxis
  • Infected cells and pathogens release chemicals that attract neutrophills to area 'distress signal'
• What is the 1st stage of phagocytosis?

  • Adherence
  • Chemical markers on the outside of cells
  • Specific to the organisms opsonins
  • protein molecules which attatch to the antigens on the pathgogens phagocyte membrane
  • have receptors for the antigens opsonins
• Whats the second stage of phagocytosis?

  • Endocytosis
  • The ingestion of the microbe by the phagocyte which recognises it as non-self
• Whats stage 3 and 4 of phagocytosis?

  • Phagosome
  • phagocyte engulfs the pathogen to form a phagosome
  • Phagolysosome
  • The fusion of phagosome with lysosome
• Whats stages 5 and 6 phagocytosis?

  • The phagolysosome gets broken down by enzymes
  • The digested phagolysosome is absorbed by phagocyte antigens combine with MHC in cytoplasm
• Whats the last stage of phagocytosis?

  • Exocytosis
  • The discharge of waste material
  • It is displayed on the phagocyte membrane
• What does the specific immune response depend on?

  • White blood cell
  • Lmyphocyte
  • Produced in bone marrow
• What are the 2 types of lymphocytes?

  • T lymphocytes or cells -
  • B lymophcytes or cells
• What are the types of immune cells?

  Types of immune cells include T cells and B cells
• Where are immune cells produced?

  Immune cells are produced in bone marrow
• What is the function of immune cells in the immune response?

  They help protect the body from pathogens
• What type of immune cell is a neutrophil?

  Neutrophils are a type of phagocyte
• Where do bone marrow cells mature?

  Bone marrow cells mature in the bone marrow
• What is the role of macrophages in the immune system?

  Macrophages engulf and digest pathogens
• What type of immune cell is involved in the adaptive immune response?

  T-lymphocytes are involved in adaptive immunity
• What do B-lymphocytes do in the immune response?

  B-lymphocytes produce antibodies against pathogens
• What is the function of memory cells?

  Memory cells provide long-term immunity
• How do plasma cells function in the immune response?

  Plasma cells secrete antibodies into the bloodstream
• What is the role of killer T cells?

  Killer T cells attack and destroy infected cells
• What do helper T cells do?

  Helper T cells stimulate other immune cells
• What is the function of memory B cells?

  Memory B cells remain in the body for years
• How do antibodies function in the immune response?

  Antibodies bind to and neutralize pathogens
• How do T cells and B cells differ in their roles?

  T cells attack infected cells; B cells produce antibodies
• What is the role of cytokines in the immune response?

  Cytokines are signaling molecules in immunity
• What is the significance of the bone marrow in the immune system?

  Bone marrow produces and matures immune cells
• How do the functions of macrophages and neutrophils compare?

  Both engulf pathogens, but macrophages are longer-lived