m6 s6 and 7

• What is an ecosystem?


  All the living organisms found in one area, and the non-living aspects of their environment.
• Why are ecosystems described as 'dynamic'?


  Because they depend on interactions between biotic and abiotic factors.
• What are biotic factors? Give an example.


  Biotic factors are living features of an ecosystem, such as predators.
• What are abiotic factors? Give an example.


  Abiotic factors are non-living features of an ecosystem, such as light.
• What is biomass?


  The total weight of living matter in a certain area.
• How is biomass transferred in an ecosystem?


  Biomass is transferred up trophic levels through consumption.
• How can biomass be measured?


  In terms of mass of carbon, or dry mass of tissue.
• What is the formula for efficiency of biomass transfer?


  Efficiency = $\frac{\text{biomass transferred}}{\text{biomass intake}} \times 100$
• How can human activities affect biomass transfer?


  By maximizing light, water, temperature, and increasing nutrients in soil.
• What are the roles of microorganisms in the nitrogen cycle?

  • Nitrogen-fixing bacteria (e.g., Rhizobium, Azotobacter) convert gaseous nitrogen into ammonia.
  • Nitrifying bacteria (e.g., Nitrosomonas) convert ammonium compounds into nitrites, and Nitrobacter converts nitrites to nitrates.
• What are the roles of organisms in the carbon cycle?


  • Respiration of plants and animals adds carbon dioxide to the atmosphere.
  • Photosynthesis of plants removes carbon dioxide from the atmosphere.
  • Decomposers (microorganisms) decay plant and animal material into carbon dioxide.
• What is primary succession?


  It is where an area previously devoid of life is colonized by a community of organisms.
• Summarize the process of primary succession.


  • Pioneer species colonize the area.
  • They die, decompose, and add nutrients to the ground.
  • This allows more complex organisms to survive over time.
• What is a climax community?


  The final stage of succession where the ecosystem is balanced and stable.
• How is a climax community reached?


  When the soil is rich enough to support large trees or shrubs, and the environment is no longer changing.
• What is deflected succession?


  It is where succession is interrupted, usually by human interference.
• What is sampling?


  Selecting a group of individuals that will represent the whole target population.
• What are methods of sampling and how are they used?


  • Quadrats: Used in small areas, randomly or regularly placed; frequency or % cover calculated.
  • Transects: Used in larger areas; samples taken along a line that crosses the habitat, can be combined with quadrats.
• What is carrying capacity?


  The maximum population size that a habitat can support, defined by limiting factors.
• What factors limit the maximum size of a population?

  • Food
  • Water
  • Light
  • Oxygen
  • Nesting sites
  • Shelter
  • Parasites
  • Predators
• Describe the pattern of a typical predator-prey relationship in terms of population change.


  • Prey is eaten by predator, increasing predator population and decreasing prey population.
  • Fewer prey leads to increased competition for food, decreasing predator population.
  • Fewer predators allow more prey to survive, restarting the cycle.
• What is intraspecific competition?


  Competition between organisms of the same species.
• What is interspecific competition?


  Competition between organisms of different species.
• Differentiate between conservation and preservation.


  • Conservation: Maintains biodiversity by allowing sustainable use of resources.
  • Preservation: Maintains biodiversity by minimizing human impact.
• Why do we conserve and preserve habitats?

  • Economic: Food source, natural pest control, boosts tourism.
  • Social: Many organisms can be used in medicine, aesthetics.
  • Ethical: Responsibility to maintain habitats for future generations.
• What is sustainability?


  Using resources in a way that maintains them for future generations.
• What methods allow sustainable use of an ecosystem’s resources?


  • Timber production: Coppicing, replacing felled trees, selective cutting.
  • Fishing: Ensuring stocks are not depleted, avoiding overfishing.
• Give an example of how the conflict between conservation and human needs can be balanced.


  In the Terai region (Nepal), locals are responsible for forest care while using it for fuel.
• Give an example of how human effects are controlled in sensitive ecosystems.

  In the Galapagos Islands, efforts are made to balance tourism and hunting impacts on endangered species.