This page was last edited by - acetone acetone on Sep 12, 2011 12:50 pm. (4 total edits)
Home | APES
FRQ | U.S. Legislation | Field Trips | Summer Work | Area IIa | Areas IIb-d


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
Click the links to see the animations full size.
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.
APES-Area2c-Ecosystem_Diversity

Area IIC Animations
Click the links to see the animations full size.
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.
APES-Area2d-Natural_Ecosystem_Change
Area IID Animations
Click the links to see the animations full size.
Succession


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.
APES-Area2e-Natural_Biogeochemical_Cycles

Area IIE Animations
Click the links to see the animations full size.
Carbon Cycle

Nitrogen Cycle

Phosphorus Cycle

Sulfur Cycle

Hydrologic Cycle

Hubbard Brook Experiment