Eco systems and Disease

• Biodiversity


  The range of different species in a community
• High biodiversity


  • A large number of different species live in an ecosystem
  • Helps stabilize an ecosystem when physical conditions change
  • Shows how healthy and responsive an ecosystem is
  • The higher the diversity the easier it is to stay in equilibrium
  • An ecosystem with many different species is likely to stay stable and less likely to be disrupted by environmental changes
• The number of predators and prey


  Tends to change as they affect each other
• Genetic biodiversity


  • Biodiversity within organisms of the same species
  • As organisms reproduce, slight variations are introduced which improve their ability to survive despite possible environmental and habitat alterations
• Threats to biodiversity


  • Over explosion - overhunting, overfishing, etc
  • Invasion of non-living species
  • Habitat loss/deforestation/degradation
  • Pollution+invasion
  • Climate change
• Photosynthesis


  1. The sun produces energy

  2. Plants use CO2 and H2O in the presence of sunlight and chlorophyll to produce Glucose (C6H12O6) and O2
• Food chains


  • Show the relationship between producers, consumers, and decomposers
  • The progressive loss of energy along the food chain explains why the chain is short
  • Show the flow of energy from one living thing to another
• Animals in ecosystems


  • They have 'special features' - adaptations - that assist in the best chance of survival
• Greenhouse effect


  • Caused by the gas CO2 together with other gases such as CH4 (Methane)
  • Too little greenhouse gases and the world would be too cold whereas too much of these gases and the world would be unsustainable to live in
  • The greenhouse effect is natural and required for survival
  • CO2 and other gases block and prevent the transmission of long-wavelength radiation from leaving the Earth's atmosphere
  • The 'blanket' of the greenhouse gases in the Earth's atmosphere has effectively become thicker, which enhances the greenhouse effect
  • The greenhouse effect has led to global warming, increasing the temperature by 0.18 every decade
• Biotic interactions


  • Predation
  • Mutualism
  • Competition
  • Parasitism
  • Commensalism
• Factors that influence an ecosystem

  • Abiotic Factors - non-living factors e.g. air quality, sunlight, etc
  • Biotic factors - Living factors e.g. predators, competition, etc
• Disease


  Any condition that interferes with the proper function of the body/mind
• Types of diseases


  • Infectious disease
  • Non-infectious disease
• Pathogens


  • Any organism or infective agent that lives in or on another living organism and causes a disease
  • To cause a disease the pathogen needs the right conditions to multiply and be transmitted
• Ways pathogens can spread

  • Direct Contact
  • Indirect contact
  • Contact with animals and insects
  • Contact with contaminated food/water
• Types of pathogens


  • Prions
  • Viruses
  • Bacteria
  • Protozoans
  • Fungi
  • Macro-parasites
• Antibiotics


  • Medicine that can either kill the pathogen or relieve symptoms of diseases to allow the body system to fight off the disease
  • Discovered accidentally in 1928 by Alexander Flemming
• Antibiotics resistance


  • Some bacteria may develop a mutation allowing them to resist a certain antibiotic
  • These bacteria can reproduce and pass this resistance to their offspring
• Vaccination


  • Triggers immune system response without experiencing the symptoms of the illness
  • Used as a preventive measure against viral infections
  • Vaccines become less effective over time and boosters are usually administered
• Methods of disease transfer

  • Airborne Droplets
  • Fecal oral
  • Blood/Bodily fluid
  • Sexually transmitted infections (STI)
• Lines of Defence


  • First Line of Defence - Physical and Chemical Barriers
  • Second Line of Defence - Inflammation
  • Third Line of Defence - Immune response
• Bacteria are microscopic, unicellular organisms that can act as pathogens and cause disease
• When green plants capture light energy - they make glucose. This is used in respiration
• The chemical reaction of photosynthesis involves carbon dioxide and water combining to form sugar and oxygen
• 90% of energy is lost in a food web, only 10% is passed upwards
• Nitrogen cycle: Process of moving nitrogen from Earth to atmosphere to living organisms
• nitrogen cycle is essential in the cycle of matter as the Earth cannot work without the specific nutrient
• Abiotic factors include temperature, rainfall, soil type, wind speed, sunlight intensity, etc.
• Ecosystems are made up of biotic (living) and abiotic factors (non-living)
• First Line of Defence

  Physical and Chemical Barriers
• First line of defense

  • Attempts to prevent the entry of pathogens
• Physical Barriers


  • Skin
  • Cilica
  • Nasal hair
• Cilia


  Small hairs in the windpipe that trap debris like dust, smoke, etc
• Chemical Barriers


  Can break down simple pathogens before they cause infection
• Chemical Barriers


  • Saliva
  • Mucus
  • Tears
• When a pathogen enters the body, 2nd line of defense begins


  1. The affected area becomes inflamed ---> red, hot, and swollen

  2. Infected cells release histamine which causes more blood to flow in the affected area

  3. Within the blood, there are special white blood cells called neutrophils

  4. The neutrophils consume pathogens that have entered the body - phagocytosis

  5. Pus can form at the infection site and is a combination of dead bacteria, dead tissue, etc
• Third Line of Defence

  Immune response
• Immune response


  • Specific - can distinguish between different types of pathogens
• White blood cells responsible

  • T cells
  • B cells
• T cells


  Responsible for identification and marking of pathogens using their antigens