Science Topic 9

Parts of an Ecosystem

  • Biotic Factors:

    • Definition: Living things in an ecosystem, such as plants, animals, and microbes.
    • Includes:
    • Plants and microbes (visible and invisible).
    • Remains of previously living organisms.
    • Waste products of living organisms.

  • Abiotic Factors:

    • Definition: Non-living components in an ecosystem.
    • Examples:
    • Sunlight
    • Water
    • Air
    • Rocks
    • Spaces (e.g., nesting sites for birds).
    • Importance: Organisms must interact with these factors.
    • Water can vary in quality (e.g., fresh vs. polluted) affecting local organisms.

Defining an Ecosystem

  • Ecosystem:
    • Definition: A complex system made up of biotic and abiotic factors interacting with one another.
    • Interaction: Every factor influences others positively or negatively.
    • Study Focus: Delineate boundaries to consider relevant factors when studying an ecosystem (e.g., deficiencies in tomato plants).

Energy in an Ecosystem

  • Energy Requirement:
    • All organisms require energy for life processes (e.g., creating proteins, transporting materials).
    • Energy must come from the environment, e.g., food, sunlight.
  • Law of Conservation of Energy:
    • Total energy in the universe remains constant.
    • Energy can transfer forms but is neither created nor lost.
  • Energy Transformation Example:
    • Frogs convert chemical energy of food into kinetic energy for movement.

Photosynthesis

  • Definition:
    • A process by which autotrophs (e.g., plants) create their food using sunlight.
  • Chemical Process:
    • Light energy + CO₂ + H₂O → sugar (C₆H₁₂O₆) + O₂
    • Sugar molecules are a form of potential energy.
  • Energy Flow:
    • Immediately used for growth and chemical reactions or stored in molecules for future use.
    • If eaten by heterotrophs, chemical energy is transferred and used by consumers.
    • Energy ultimately derives from sunlight, emphasizing the sun’s role as the primary energy source in ecosystems.

Cellular Respiration

  • Definition:
    • Process of breaking down sugar (C₆H₁₂O₆) using oxygen (O₂) to produce usable energy.
    • All living organisms, including plants and animals, undergo this process.
  • Energy Flow:
    • Chemical energy from sugars comes originally from the sun (via photosynthesis).
    • Autotrophs convert light energy into potential chemical energy which is then used through cellular respiration by themselves and consumers.

Transformation of Energy

  • Energy Transformation in Respiration:
    • Energy released from sugars transforms into various forms:
    • Kinetic energy (movement).
    • Thermal energy (heat).
  • Food Chains & Webs:
    • Food chains represent how energy flows between organisms; numerous food chains create a food web.
    • Starts with sunlight, leading to autotrophs that create their own food.

Fermentation

  • Definition:
    • An energy production method that occurs in anaerobic environments (absence of oxygen).
    • Types:
    • Alcoholic Fermentation:
      • Product: Alcohol and CO₂.
      • Application: Used in baking (yeast in bread).
    • Lactic Acid Fermentation:
      • Occurs during intense exercise when muscles lack oxygen.
      • Result: Burning sensation from the buildup of lactic acid.
  • Energy Yield:
    • Fermentation produces significantly less energy compared to aerobic respiration.

Conservation of Matter and Energy

  • Laws:
    • Law of Conservation of Mass: Mass is neither created nor destroyed; can change form during chemical/physical changes.
    • Law of Conservation of Energy: Energy transformations occur without loss of total energy.
  • Example:
    • In a terrarium, the mass remains constant as components (plants, soil, air) cycle.

Water Cycle

  • Water's Role:
    • Essential abiotic component of ecosystems.
  • Processes of Water Cycle:
    • Evaporation:
    • Process where water transitions from liquid to gas due to sunlight.
    • Occurs in bodies of water and through plant transpiration.
    • Condensation:
    • Cooling of water vapor that forms tiny droplets, resulting in clouds.
    • Precipitation:
    • Collection of condensed water that falls as rain, snow, etc.
  • Resulting Paths:
    • Water can become groundwater or run off to rivers/lakes.

Carbon and Oxygen Cycles

  • Importance of Carbon:
    • Building block of life, present in proteins and bones.
  • Carbon Cycle:
    • Producers absorb CO₂ during photosynthesis, converting it into food.
    • Consumers obtain carbon from food.
    • Decomposers return carbon to soil/air after breaking down organic material.
  • Oxygen Cycle:
    • Oxygen is released by producers during photosynthesis and used by most organisms in cellular respiration.
  • Conservation Laws:
    • Carbon and oxygen atoms are recycled; total quantity remains constant.
  • Human Influence:
    • Activities such as burning fossil fuels and deforestation increase atmospheric CO₂ levels, disrupting equilibrium.

Nitrogen Cycle

  • Role of Nitrogen:
    • Essential for building proteins; atmospheric nitrogen is mostly unusable.
  • Nitrogen Fixation:
    • Process converting atmospheric nitrogen (N₂) to usable nitrogen compounds, primarily by bacteria and during lightning.
    • Legume plants host nitrogen-fixing bacteria in root nodules.
  • Usage of Nitrogen:
    • Producers utilize fixed nitrogen to make proteins.
    • Consumers acquire nitrogen through consumption, recycling through the ecosystem.
  • Cycle Continuity:
    • After being used, nitrogen can be broken down and returned to the atmosphere as free nitrogen.