BIOLOGY

• A pathogen is a disease causing organism
• A transmissible disease is a disease that can be passed from one host to another
• A pathogen is transmitted through;

  1. Indirect contact
  2. Direct contact
• Direct contact pathogen transmission:

  1. Through blood
  2. Through bodily fluids
• Indirect contact pathogen transmission :

  1. Through contaminated surfaces
  2. Through raw meat , food
  3. Through animals
  4. Through air (sneezes & coughs)
• Diseases can be controlled by:

  1. Clean water supply
  2. Sewage Treatment
  3. Good personal hygiene
  4. Proper waste disposal
  5. Hygienic food preparation
• Active immunity is the defense against a pathogen by antibody production in the body
• An antigen is a chemical recognized by the immune system
• Antigens stimulate the production of antibodies
• Specific antibodies have complementary shapes with specific antigens
• Antibodies are proteins that bind onto pathogens which either destroy them or MARK pathogens for destruction by phagocytes
• Active immunity is gained by :

  1. vaccination
• Active immunity is gained by :

  1. Infection from a pathogen
  2. vaccination
• During vaccination;

  A harmless form of a pathogen is introduced to the body by injection or swallowing. The presence of a pathogen triggers white blood blood cells to produce specific antibodies to fight possible infection and produce memory cells which give long term immunity.
• Passive immunity is a short term defense against pathogens by antibodies from other individuals e.g Breastfeeding & the placenta

  * does not produce memory cells
• The first line of defence is physical barriers such as skin, mucous membranes, cilia etc.
• Cholera is a disease caused by a bacterium that is transmitted through contaminated water
• Cholera works by:

  Cholera bacterium are ingested and multiply then the bacteria attach themselves to the wall of the alimentary canal. The bacteria releases a toxin which stimulates the cells lining in the intestine to secrete chloride ions which increases the concentration of fluid in the lumen, lowering water potential and now causes DEHYDRATION
• Treatment for Cholera includes rehydration therapy (IV fluids) and antibiotics
• Symptoms of Malaria include fever, headache, muscle pain, vomiting and fatigue
• Blood includes;

  1. Red Blood cells
  2. White blood cells
  3. Platelets
  4. Plasma
• Platelets -> Fibrinogen -> Fibrin
• Plasma transports:

  1. Urea
  2. Carbon dioxide
  3. Waste products
  4. Mineral ions
• Blood clotting prevents loss of blood and entry of pathogens into the body
• Trachea is the tube which air travels to the lungs
• Cartilage is used to prevent the trachea from collapsing
• The thorax is the chest
• Gaseous exchange happens in the alveoli
• Alveoli are tiny sacs where gases diffuse across the walls
• Alveoli are good for gaseous exchange due to ;

  1. Thin so that capillaries can receive diffused oxygen into the blood
  2. Good transport system
  3. Large surface area
  4. Good oxygen supply
• Ventilation is the movement of air in and out of the lungs by breathing movements
• In the alveoli:

  1. Carbon dioxide diffuses out of the blood
  2. Oxygen diffuses into the blood
• When we breath in;

  1. Diaphragm contracts
  2. Internal intercoastal muscles relax
  3. External intercoastal muscles contract
  4. Volume increases
  5. Pressure decreases
• When we breath out:

  1. Pressure increases
  2. Internal intercoastal muscles contract
  3. External intercoastal muscles relax
  4. Volume decreases
  5. Diaphragm relaxes
• Movement


  An action by an organism or a part of an organism causing a change of position or place
• Metabolism


  Chemical reactions that take place in the body
• Anabolism


  When a complex molecule is formed from simpler ones
• Catabolism


  When a complex molecule is broken down into a simple molecule
• Respiration


  The chemical reactions in the cell that break down nutrient molecules and release energy for metabolism
• Sensitivity


  The ability to detect or sense stimuli in the internal or external environment and make appropriate responses