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Ecosystems and Energy in General Biology

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이 집합의 용어 (28)

  • What defines an ecosystem?
    An ecosystem consists of all organisms living in a community plus the abiotic factors with which they interact.
  • What are the two main processes in ecosystem dynamics?
    Energy flow and chemical cycling are the two main processes; energy flows through ecosystems, while matter cycles within them.
  • State the first law of thermodynamics in the context of ecosystems.
    Energy cannot be created or destroyed, only transferred or transformed; energy enters ecosystems as solar radiation and is transformed by photosynthesis.
  • What does the second law of thermodynamics imply for ecosystems?
    Every energy exchange increases entropy; energy conversions are inefficient, and some energy is lost as heat, requiring continuous solar input.
  • Explain the law of conservation of mass in ecosystems.
    Matter cannot be created or destroyed; chemical elements are continually recycled within ecosystems through uptake, transformation, and decomposition.
  • How do ecosystems gain or lose elements?
    Ecosystems are open systems that absorb energy and mass and release heat and waste; elements enter as dust or solutes and leave via water or other pathways.
  • What is the role of autotrophs and heterotrophs in energy and mass transfer?
    Autotrophs build molecules using photosynthesis or chemosynthesis; heterotrophs depend on autotrophs' biosynthetic output for energy.
  • Define detritivores and their ecological role.
    Detritivores consume nonliving organic matter (detritus); they connect all trophic levels by decomposing organic material.
  • What is primary production in ecosystems?
    Primary production is the amount of light energy converted to chemical energy by autotrophs during a given time period.
  • Differentiate between gross primary production (GPP) and net primary production (NPP).
    GPP is total chemical energy from photosynthesis; NPP is GPP minus energy used for autotrophic respiration, representing energy available to consumers.
  • Why is standing crop not a reliable indicator of NPP?
    Standing crop is total biomass at a time, but slow-growing ecosystems may have high biomass with low new biomass production.
  • What limits primary production in aquatic ecosystems?
    Both light penetration and nutrient availability limit production; nitrogen and phosphorus are common limiting nutrients.
  • What is eutrophication and its ecological impact?
    Eutrophication is nutrient enrichment causing phytoplankton blooms, increased decomposition, oxygen depletion, and loss of fish species.
  • What factors control primary production in terrestrial ecosystems?
    Temperature and moisture, including precipitation and evapotranspiration, are main factors controlling terrestrial primary production.
  • How do plants adapt to nutrient limitations in soil?
    Plants form mutualisms with nitrogen-fixing bacteria and mycorrhizal fungi, have root hairs to increase surface area, and release enzymes to access nutrients.
  • What is production efficiency in secondary production?
    Production efficiency is the fraction of energy stored in food used for growth and reproduction; varies by organism type.
  • What is trophic efficiency and its average value?
    Trophic efficiency is the percentage of production transferred between trophic levels, averaging about 10%.
  • Describe the shape of biomass pyramids in most ecosystems.
    Biomass pyramids typically show a sharp decrease in biomass at successively higher trophic levels.
  • What role do decomposers play in nutrient cycling?
    Decomposers break down organic matter, releasing inorganic nutrients back into the ecosystem for reuse.
  • What factors influence decomposition rates in ecosystems?
    Temperature, moisture, and nutrient availability control decomposition rates, affecting nutrient cycling speed.
  • What distinguishes biogeochemical cycles?
    They involve both biotic and abiotic components and may be global (gaseous elements) or local (heavier elements).
  • Summarize the water cycle's key processes and reservoirs.
    Key processes include evaporation, transpiration, condensation, precipitation, and movement through surface and groundwater; oceans hold 97% of biosphere water.
  • Outline the carbon cycle's biological importance and key processes.
    Carbon is essential for organic molecules; photosynthesis takes up CO2, respiration and fossil fuel burning release CO2.
  • What are the main forms and processes in the nitrogen cycle?
    Nitrogen forms include NH4+, NO3-, and organic forms; processes include fixation, nitrification, denitrification, and assimilation.
  • Describe the phosphorus cycle's reservoirs and key processes.
    Phosphorus reservoirs include sedimentary rocks and soil; key processes are weathering, leaching, uptake, excretion, and decomposition.
  • What was learned from the Hubbard Brook Experimental Forest study?
    Internal nutrient cycling conserves most minerals; deforestation increases water and nutrient loss, especially nitrates.
  • What is bioremediation in ecosystem restoration?
    Bioremediation uses organisms like prokaryotes, fungi, or plants to detoxify ecosystems by metabolizing toxic molecules.
  • What is biological augmentation?
    Biological augmentation adds essential materials to degraded ecosystems, e.g., nitrogen-fixing plants or mycorrhizal fungi.