Biology topic 9

• What is the main topic of the study material?

  Ecosystems and Material Cycles
• How are ecosystems organized?

  Into different levels of organization
• What is a community in ecological terms?

  All the organisms of species living in a habitat
• What does interdependence mean in a community?

  Organisms depend on each other for survival
• What is mutualism?

  A relationship where both organisms benefit
• What is parasitism?

  A relationship where one organism benefits and the other is harmed
• How do environmental changes affect communities?

  They can change the distribution of populations
• How does water availability affect daisies?

  They grow best in slightly damp soils
• What happens to grasses as trees grow?

  Grasses may be replaced by fungi
• What is the effect of high sulfur dioxide levels on lichens?

  Lichens cannot survive high concentrations
• What is competition in ecosystems?

  Organisms compete for the same resources
• How do red and grey squirrels compete?

  For the same food resources
• What happens if the number of lions decreases?

  The number of gazelles might increase
• What is the procedure for using quadrats to study small organisms?

  1. Place a 1 m² quadrat randomly in the sample area.
  2. Count the organisms within the quadrat.
  3. Repeat multiple times for accuracy.
  4. Calculate the mean number of organisms per quadrat.
• How do you calculate the mean number of organisms per quadrat?

  Total organisms counted divided by number of quadrats
• If Isha counted 154 daisies in 7 quadrats, what is the mean?

  22 daisies per quadrat
• How do you estimate the population size of daisies in a field?

  Multiply mean by total area of the field
• If the mean number of daisies is 10 per quadrat in an 800 m² field, what is the estimated population?

  16,000 daisies in the field
• What is the procedure for using belt transects to study distribution along a gradient?

  1. Mark a line in the study area.
  2. Place quadrats next to each other along the line.
  3. Count organisms or estimate percentage cover.
  4. Record abiotic factors.
  5. Repeat and find mean values.
• What should you remember about correlation in data interpretation?

  Correlation does not imply causation
• What are the roles of producers and consumers in a food chain?

  • Producers make their own food using sunlight.
  • Primary consumers eat producers.
  • Secondary consumers eat primary consumers.
• What is the source of energy for nearly all life on Earth?

  The Sun
• How do plants use light energy?

  To convert CO2 and water into glucose
• What do primary consumers do with the energy they obtain?

  They use some energy and store the rest
• What is biomass?

  The mass of living material in an organism
• What happens to energy as it moves through a food chain?

  Some energy is lost at each trophic level
• Why are long, unbroken food chains rare in ecosystems?

  Many options for consumption and evasion exist
• What is the role of producers in an ecosystem?

  Producers make their own food using sunlight
• Who eats primary consumers?

  Secondary consumers eat primary consumers
• Why are long, unbroken food chains rarely seen in ecosystems?

  Many options for organisms to consume exist
• What is the source of energy for nearly all life on Earth?

  The Sun is the source of energy
• How do plants convert light energy?

  Plants convert light energy into glucose via photosynthesis
• What happens to glucose produced by plants?

  Some is used in respiration, some stored as biomass
• What does a secondary consumer eat?

  A secondary consumer eats primary consumers
• What is a trophic level?

  Each stage of a food chain is a trophic level
• How is energy used by organisms at each trophic level?

  Energy is used for respiration and life processes
• What happens to energy lost at each stage of a food chain?

  It is lost to the surroundings as heat
• Why is energy not transferred to the next trophic level?

  Not all of an organism gets eaten or digested
• Why are food chains rarely longer than five trophic levels?

  Energy loss limits support for more organisms
• What do pyramids of biomass represent?

  • Show the amount of biomass at each trophic level
  • Each bar is drawn to scale
  • Indicates energy stored in each level