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Area II: The Living World (10-15%)

Area IIB: Energy Flow (Main ideas from Living in the Environment, 14th Edition, by G. Tyler Miller, Jr.)

4-3 Ecosystem Components
  • The major components of ecosystems are abiotic (nonliving) water, air, nutrients, solar energy, and biotic (living) plants, animals, and microbes.

4-4 Energy Flow in Ecosystems
  • Food chains and food webs help us understand how eaters, the eaten, and the decomposed are interconnected in an ecosystem.
  • Energy flow in a food web/chain decreases at each succeeding organism in a chain or web.
  • The dry weight of all organic matter within the organisms of a food chain/web is called biomass.
  • Ecological efficiency is the term that describes the percentage of usable energy transferred as biomass from one trophic level to another and ranges from 2%–40% with 10% being typical.
  • The greater number of trophic levels in a food chain, the greater loss of usable energy.
  • The pyramid of energy flow visualizes the loss of usable energy through a food chain.

4-5 Primary Productivity of Ecosystems
  • Production of biomass takes place at different rates among different ecosystems.
  • The planet’s net primary productivity (NPP) limits the number of consumers who can survive on Earth.
  • Humans are using, wasting, and destroying biomass faster than producers can make it.
APES-Area2b-Energy Flow

Area IIB Animations
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Energy Flow

Energy Flow in Silver Springs, FL

Matter and Energy

Ecosystem Roles

Rainforest Food Web

Area IIC: Ecosystem Diversity (Main ideas from Living in the Environment, 14th Edition, by G. Tyler Miller, Jr.)

5-1 Origins of Life
  • Chemical evolution of organic molecules, biopolymers, and systems of chemical reactions were needed to form the first cell. It took about 1 billion years
  • Biological evolution followed, from single-celled prokaryotic bacteria to single-celled eukaryotic organisms to multicellular organisms. Is has been continuing for 3.7 billion years.
  • Knowledge of past life comes from fossils, ice-core drilling, chemical analysis, and DNA analysis.

5-2 Evolution and Adaptation
  • Evolution is the change in a population’s genetic makeup over time.
  • All species descend from earlier, ancestral species.
  • Microevolution describes the small genetic changes that occur in a population over time; over time, a population’s gene pool changes when mutations (beneficial changes) in DNA molecules are passed on to offspring. There may be several different forms (alleles) of a single gene.
  • Natural selection’s role in microevolution occurs when members of a population have genetic traits that improve their ability to survive and produce offspring with those specific traits.
  • Interactions between species can result in microevolution in each of their populations, a process called coevolution.

5-4 Speciation, Extinction, and Biodiversity
  • Natural selection can lead to development of an entirely new species.
  • When population members cannot adapt to changing environmental conditions, the species becomes extinct.
  • When local environmental conditions change, some species will disappear at a low rate; this is called background extinction.
  • Mass extinction is a significant rise in extinction rates above the background extinction level.
  • It takes one to ten million years to rebuild biological diversity after a mass extinction/depletion.
  • The Earth’s biodiversity is decreasing because of human activities.

5-5 What is the Future of Evolution?
  • Man has used artificial selection to change the genetic characteristics of populations.
  • Genetic engineering is an unpredictable process and raises privacy, ethical, legal, and environmental issues. It is a trial and error process.

Area IIC Animations
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Tree of Life

Peppered Moth Selection

Stabilizing Selection

Disruptive Selection

Area IID: Natural Ecosystem Change (Main ideas from Living in the Environment, 14th Edition, by G. Tyler Miller, Jr.)

8-5 Ecological Succession: Communities in Transition
  • With new environmental conditions, community structures can change; one group of species is replaced by another; ecological succession is the gradual change in species composition of a given area.
  • Primary ecological succession is the gradual establishment of biotic communities on lifeless ground.
  • Secondary ecological succession defines a series of communities with different species developing in places with soil or bottom sediment.
  • The classic view of ecological succession is that it is an orderly sequence, each stage leading to the next, more stable stage until a climax community is reached.

8-6 Ecological Stability, Complexity, and Sustainability
  • Living systems maintain some degree of stability or sustainability through constant change in response to changing environmental conditions.
  • Some communities obtain ecological stability or sustainability by having many different species present.

9-3 Effects of Genetic Variations on Population Size
  • Variations in genetic diversity can affect the survival of small, isolated populations.
Area IID Animations
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Area IIE: Natural Biogeochemical Cycles (Main ideas from Living in the Environment, 14th Edition, by G. Tyler Miller, Jr.)

4-7 Matter Cycling in Ecosystems
  • Nutrient cycles/biogeochemical cycles are global recycling systems that interconnect all organisms.
  • The water/hydrologic cycle collects, purifies, and distributes the earth’s water in a vast global cycle.
  • The carbon cycle circulates through the biosphere. Carbon moves through water and land systems, using processes that change carbon from one form to another; excess carbon dioxide being added to the atmosphere through our use of fossil fuels and our destruction of the world’s photosynthesizing vegetation has contributed to global warming.
  • Nitrogen is recycled through the earth’s systems by different types of bacteria.
  • We need to use phosphorus-based fertilizers because the phosphorus cycle is much slower in moving through the earth’s water, soil, and organisms and is often the limiting factor for plant growth.
  • Sulfur cycles through the earth’s air, water, soil, and living organisms. Much is sorted in rocks and minerals, buried deep under ocean sediments.

Area IIE Animations
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Carbon Cycle

Nitrogen Cycle

Phosphorus Cycle

Sulfur Cycle

Hydrologic Cycle

Hubbard Brook Experiment