Topic 9- Ecosystems and Material Cycles

• What do organisms depend on each other for in ecosystems?

  Food and shelter
• What does interdependence mean in an ecosystem?


  Species rely on each other for survival
• How can a change in one species' population affect others in the community?

  It can cause knock-on effects for other species
• What factors can cause changes in the environment of organisms?

  Biotic and abiotic factors
• What are abiotic factors?

  Non-living environmental factors
• What are biotic factors?

  Living environmental factors
• How do abiotic factors affect communities?

  They can cause stress or changes in population
• How do biotic factors affect communities?

  They influence competition and predation
• What are the steps to use a quadrat for studying organisms?


  1. Place a quadrat randomly in the sample area
  2. Count organisms within the quadrat
  3. Note the species observed
  4. Repeat several times
  5. Calculate the mean number of organisms
  6. Compare means from different areas
• What is a quadrat?

  A square frame for sampling area
• Why is it important to place a quadrat randomly?

  To ensure representative sampling of the area
• How do you estimate population size using quadrats?

  Multiply mean organisms per quadrat by total area
• If a quadrat has an area of $0.5 \text{ m}^2$ and the mean is 10 daisies, what is the mean per $1 \text{ m}^2$?


  $20\text{ daisies per m}^2$
• What is a belt transect used for?

  Studying distribution along a gradient
• What are the steps to use a belt transect?

  1. Mark a line in the study area
  2. Collect data using adjacent quadrats
  3. Count organisms or estimate percentage cover
  4. Record abiotic factors
  5. Repeat and find mean values
  6. Plot graphs to analyze data
• What is the source of energy for nearly all life on Earth?

  The Sun
• How do plants convert light energy?

  Into chemical energy during photosynthesis
• What happens to energy as it moves up the food chain?

  Most energy is lost at each stage
• Why is energy not fully transferred to the next trophic level?

  Some energy is used for life processes
• What is a pyramid of biomass?

  A diagram showing weight at each food chain level
• What does a pyramid of biomass illustrate?

  Energy stored at each stage in the food chain
• How do you calculate energy lost between trophic levels?

  Subtract energy transferred from previous level
• What is the efficiency formula for energy transfer?

  $\text{efficiency} =$$\frac{\text{energy transferred}}{\text{energy available}} \times 100$
• What happens to biomass as you move up the food chain?

  Biomass decreases at each trophic level
• What is the energy available at the first trophic level in the example food chain?

  80,000 kJ
• How do you calculate the efficiency of energy transfer between levels?

  Use the efficiency formula provided
• What is the impact of farming fish in open water?

  It can reduce biodiversity in surrounding areas
• What is a non-indigenous species?

  A species not native to an area
• How do non-indigenous species affect indigenous species?

  They compete for resources and can reduce populations
• What is reforestation?

  Planting trees in deforested areas
• How does reforestation affect biodiversity?

  It increases biodiversity in deforested areas
• What does sustainability mean in the context of food security?

  Meeting current needs without compromising future needs
• How do new pests and pathogens affect food security?

  They can damage crops and reduce yields
• What is the carbon cycle?

  A process of recycling carbon in the environment
• How do plants use carbon from CO₂?

  To make carbohydrates, fats, and proteins
• What happens to carbon compounds in a food chain?

  They are passed from plants to animals
• What do organisms release back into the atmosphere?

  CO₂ during respiration
• What is a basic term for the carbon cycle?

  Old carbon for nature
• What does the carbon cycle illustrate about carbon in the environment?

  Carbon is constantly recycled
• What is the primary process that powers the carbon cycle?

  Photosynthesis