Biology Chapter 2.1: Ecosystems and Populations
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Questions and Answers

What happens to the average biomass of organisms during the season after breeding when many young are present?

  • It remains constant.
  • It decreases. (correct)
  • It increases significantly.
  • It becomes unpredictable.

    • In aquatic ecosystems, which group typically has a greater biomass than the other?

  • Phytoplankton compared to zooplankton.
  • Zooplankton compared to phytoplankton. (correct)
  • Phytoplankton and zooplankton have equal biomass.
  • Neither group has a measurable biomass.

    • What characterizes the Pyramid of Productivity in terms of energy flow?

  • It shows increasing energy flow as you move up.
  • It is always the widest at the top.
  • It shows decreasing energy flow as you move up. (correct)
  • It is the same width at all levels.

    • Why does variation occur in the steepness of the energy pyramid?

    <p>Based on how efficiently energy is transferred between levels.</p> Signup and view all the answers

    What is one reason energy flow decreases with each trophic level in an ecological pyramid?

    <p>Energy loss occurs as heat.</p> Signup and view all the answers

    What is the primary characteristic that defines a species?

    <p>A group of organisms that can interbreed and produce fertile offspring</p> Signup and view all the answers

    Which of the following best describes an ecosystem?

    <p>A community of organisms and their physical environment, interacting as a system</p> Signup and view all the answers

    What role does a decomposer play in an ecosystem?

    <p>They recycle nutrients from dead organic matter back into the ecosystem</p> Signup and view all the answers

    In a food chain, energy is typically lost as heat at each trophic level. What is the primary reason for this loss?

    <p>Organisms use energy for growth and reproduction</p> Signup and view all the answers

    Which of the following accurately describes a niche?

    <p>The role an organism plays and its interactions with the environment</p> Signup and view all the answers

    Which type of organism is classified as a herbivore?

    <p>Cows, which primarily eat plants</p> Signup and view all the answers

    Which of the following statements about abiotic factors is correct?

    <p>They include non-living components such as temperature and pH</p> Signup and view all the answers

    What distinguishes a carnivore in an ecosystem?

    <p>They exclusively consume other animals for food</p> Signup and view all the answers

    What is the primary energy source for parasites?

    <p>Living host tissue</p> Signup and view all the answers

    What term is used to describe the maximum population size that an environment can sustain?

    <p>Carrying Capacity</p> Signup and view all the answers

    What is the difference between Gross Primary Productivity (GPP) and Net Primary Productivity (NPP)?

    <p>GPP is total energy, NPP is energy after respiration.</p> Signup and view all the answers

    Which statement best describes biomagnification?

    <p>Pollutants increase in concentration as they move up the food chain.</p> Signup and view all the answers

    What does carbon sequestration primarily aim to achieve?

    <p>Capture and store carbon dioxide</p> Signup and view all the answers

    What is the primary factor that limits energy transfer between trophic levels?

    <p>Heat loss during energy transformations</p> Signup and view all the answers

    What characteristic defines a J-Curve in population dynamics?

    <p>Population grows rapidly in ideal conditions.</p> Signup and view all the answers

    Which form of biomass measurement involves burning a dried sample?

    <p>Calorimetry</p> Signup and view all the answers

    In an ecological pyramid, which scenario may cause an inverted pyramid of numbers?

    <p>Single large producer supports many consumers.</p> Signup and view all the answers

    What happens to entropy according to the Second Law of Thermodynamics?

    <p>Entropy increases due to energy loss in transformations.</p> Signup and view all the answers

    What type of energy source do scavengers rely on?

    <p>Decomposing organic matter</p> Signup and view all the answers

    Which of the following describes a source in carbon cycling?

    <p>Burning fossil fuels releasing more carbon</p> Signup and view all the answers

    Which statement best describes the Third Law of Thermodynamics?

    <p>Entropy approaches a minimum as temperature approaches absolute zero.</p> Signup and view all the answers

    What role do keystone species play in an ecosystem?

    <p>They greatly influence the structure and health of their ecosystem.</p> Signup and view all the answers

    Study Notes

    2.1 Individuals, Populations, Communities, and Ecosystems

    • Atmosphere: Layer of gases surrounding Earth.
    • Hydrosphere: All water on Earth (oceans, lakes, glaciers).
    • Lithosphere/Geosphere: Earth's rocky part.
    • Biosphere: All living organisms on Earth.
    • Individual: Single organism of a species.
    • Species: Group of organisms interbreeding to produce fertile offspring.
    • Population: Organisms of the same species in the same area.
    • Community: Interacting populations in the same area.
    • Ecosystem: Community and its physical environment, interacting as a system, including biotic (living) and abiotic (non-living) components.
    • Abiotic Factors: Non-living factors affecting populations (temperature, sunlight, pH, salinity, soil texture).
    • Biotic Factors: Living factors affecting populations (predators, diseases, food, competition).
    • Habitat: The physical environment where an organism lives (abiotic factors only).
    • Niche: An organism's role in its ecosystem, including interactions and environmental requirements (biotic and abiotic factors).

    2.2 Energy and Biomass in Ecosystems

    • Energy Flow: Energy flows through food chains/webs from producers to consumers.
    • Trophic Level: Step in a food chain (producers, primary consumers, secondary consumers).
    • Energy Loss: Energy lost as heat at each trophic level, limiting chain length.
    • Decomposers: Break down dead organic matter, recycling nutrients.
    • Detrivores: Internal digesters, feeding on dead organic matter (e.g., worms).
    • Saprotrophs: External digesters, secreting enzymes to decompose matter and absorbing nutrients (e.g., mushrooms).
    • Herbivores: Eat only plants (e.g., cows).
    • Carnivores: Eat only meat (e.g., lions).
    • Omnivores: Eat both plants and meat (e.g., humans).
    • Producers (Autotrophs): Use photosynthesis to convert sunlight to chemical energy (e.g., plants, algae).
    • Predators: Hunt, kill, and consume other animals.
    • Parasites: Live on or in a host, deriving nutrients.
    • Scavengers: Feed on dead animals and plant matter.
    • Productivity: Rate of energy or biomass production.
    • Gross Primary Productivity (GPP): Total energy captured by producers.
    • Net Primary Productivity (NPP): Energy remaining after respiration (GPP - Respiration).
    • Ecological Efficiency: Only about 10% of energy transfers to the next trophic level. Issues include inefficient digestion and incomplete consumption.
    • Biomass: Total mass of living organisms (often dry weight). Measurement methods include drying and weighing, combustion/calorimetry, and extrapolation.

    2.3 Biogeochemical Cycles

    • Carbon Cycle: Movement of carbon between atmosphere, organisms, and Earth (photosynthesis, respiration, decomposition).
    • Human Impact: Deforestation and fossil fuel burning disrupt the cycle, causing climate change and ocean acidification.
    • Carbon Sequestration: Capturing/storing CO₂ to reduce atmospheric levels.
    • Natural Sequestration: Plants absorbing CO₂ during photosynthesis, soils and oceans storing carbon.
    • Artificial Sequestration: Technologies like carbon capture and storage (CCS).

    Key Terms and Definitions

    • Bioaccumulation: Pollutants accumulating in an organism over time.
    • Biomagnification: Pollutants increasing in concentration up the food chain.
    • Carrying Capacity: Maximum population size an environment can sustain.
    • Keystone Species: Species with significant impact on its ecosystem.
    • Carbon Sink: System absorbing more CO₂ than it releases.
    • Carbon Source: System releasing more CO₂ than it absorbs.
    • Carbon Store: System where carbon is balanced, neither significantly absorbed nor released.
    • Three Laws of Thermodynamics:
      • First Law: Energy cannot be created or destroyed, only transferred.
      • Second Law: Energy transformations are inefficient, some energy lost as heat (increasing entropy).
      • Third Law: As temperature approaches absolute zero, particle motion slows, and entropy approaches a minimum (absolute zero cannot be reached).

    Population Growth Curves

    • J-Curve (Exponential Growth): Rapid population growth in ideal conditions (unlimited resources, no predation), eventually unsustainable.
    • S-Curve (Logistic Growth): Population growth slows as it reaches the carrying capacity, reflecting real-world limitations.

    Pyramids of Numbers, Biomass, and Productivity

    • Pyramid of Numbers: Number of organisms at each trophic level, can be inverted depending on organism densities.
    • Pyramid of Biomass: Biomass (total mass) at each trophic level, can be inverted in aquatic ecosystems.
    • Pyramid of Productivity: Energy flow through trophic levels, always upright due to energy loss. Variations occur based on energy transfer efficiency.

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    Description

    Explore the interrelationships between individuals, populations, communities, and ecosystems in this quiz. Understand key concepts such as abiotic and biotic factors, habitats, and niches. Test your knowledge on how these elements interact to form the biosphere.

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