GENVI

• Environment is composed of the four spheres of the earth: atmosphere, lithosphere, hydrosphere, and biosphere
• Abiotic components of the environment are non-living physical and chemical factors like air, water, soil, mineral, and sunlight
• Biotic components of the environment are living biological factors such as plants, animals, microorganisms, and humans
• Ecosystem is made up of interacting biotic and abiotic components that together make up an ecosystem
• Material flow in ecosystems occurs in biogeochemical cycles like the water cycle, carbon cycle, nitrogen cycle, sulfur cycle, and phosphorus cycle
• Energy flow in ecosystems occurs in different trophic levels involving producers and consumers
• Biomes are large ecosystems with distinct biotic and abiotic characteristics that provide a life support system for organisms
• Environmental Science is an applied science that uses ecosystem concepts and principles to address environmental issues due to human activities
• Environmental Science is interdisciplinary and covers various subject matters related to the environment
• Environmental Science branches include environmental engineering, environmental chemistry, and atmospheric science, all aiming to provide solutions to environmental problems
• Knowledge about the life-supporting environment is essential to understand how the natural and physical worlds interact
• Understanding environmental problems involves knowing their causes and effects on the environment
• Addressing environmental issues involves finding solutions like natural resource management, conservation of ecosystems, preservation of biodiversity, and pollution control
• Environmental science enhances people's awareness through skills acquisition, active participation, evaluation ability, attitude development, knowledge gain, and environmental awareness
• Limiting factors are ecological stresses that restrict the ability of an organism to grow, survive, or reproduce
• Abiotic factors that can be limiting include water, temperature, salinity, pH, light, nutrients, and space
• Biotic factors that can be limiting include interactions such as parasitism, predation, and competition
• Temperature:

  • Low temperatures limit physiological activity time
  • High temperatures also impose severe constraints on organisms
  • Organisms can cool themselves through sweating, panting, defecating
  • Many organisms are adapted to withstand high temperatures
  • Pyrophytic plants need fire for seed reproduction
• Salinity:

  • Salt concentrations affect water uptake
  • Higher salt concentrations increase osmotic resistance to water uptake
  • Halophytes are plants adapted to withstand highly saline conditions
• pH:

  • Acidity or alkalinity affects plant and animal distribution
  • Most plant roots are damaged below pH of 3 or above pH of 9
  • Soil pH influences factors affecting plant growth
• Soil quality:

  • Low nutrient availability is associated with low soil temperatures and anaerobic conditions
  • Components of soil affect nutrient availability for each species
  • Pine needles can decrease soil pH, inhibiting growth of other plants
• Light:

  • Important limiting resource for plants affecting daily and seasonal rhythms
  • Light and dark reactions in photosynthesis
• Water Availability:

  • Limits distribution and abundance of many species
  • Rate of evaporation and transpiration depend on temperature
• Liebig’s Law of the Minimum:

  • Plants require certain amounts of nutrients to grow properly
  • Growth and survival are determined by the least available mineral nutrient
• Shelford’s Law of Tolerance:

  • Too much or too little of a requirement for survival is limiting to organisms
• Range of Tolerance:

  • Organisms can tolerate changes within their range of tolerance
  • Optimum range allows normal physiological processes
  • Zones of physiological stress make it difficult for organisms to grow, reproduce, and survive
  • Zones of intolerance lead to organism death
• Homeostasis:

  • Organisms maintain internal stability despite external changes
  • Failure to maintain homeostasis can lead to adverse effects and death
  • Feedback mechanisms help maintain homeostasis
• Anthropogenic activities that upset the balance of external factors can be limiting to organisms