EOC Review 08-09
Goal 5: The learner will develop an understanding of ecological relationships among
organisms.
ECOLOGY
Relate photosynthesis and cellular respiration to the carbon cycle.
-Photosynthesis removes CO2 from the atmosphere and incorporates it into the biotic portion of the ecosystem.
-Cellular respiration produces CO2 which is released into the environment.
- Formula for Photosynthesis 6CO2 + 6H2O ----- C6H12O6 + 6O2
-Producer- an organism capable of producing it's own food. EX: plants and algae
-Consumer- an organism that is unable to produce it's own food.
-Decomposer-an organism such as fungi that breaks down and absorbs nutrients from dead organisms.
-Food Chain- a series of steps from producers to consumers to decomposers by which food and energy are
transferred through the environment. Remember, the arrows represent the flow of energy in the food chain.
-Food web- an interconnected series of food chains.
- niche- the role a species plays in the environment. Includes conditions it can tolerate, methods it uses to
obtain resources and all other interactions with its environment.
-Flow of Energy in a community- It flows through in a line rather than in a cycle like food. There must
be a constant input of energy from the sun.
-Abiotic factors are nonliving parts of an organism’s environment such as sunlight, temperature, and
precipitation
-Biotic factors are all the living organisms that inhabit an environment.
-biotic potential- the highest possible rate of reproduction for a given population under ideal conditions.
-limiting factors- circumstances that keep populations from reaching their biotic potential.
Density dependent limiting factors – a variable related to the density of a population that affects
population size. Ex: shortages of food or nesting sights.
Density independent limiting factors – a variable that affects population size the same way regardless of
population density. Ex: weather, floods, and fire.
-population – group of organisms of the same species, which interbreed and live in the same place at the same
time.
-community- collection of several interacting populations that inhabit a common environment.
- ecosystem- interactions among the populations in a community and the communities physical surroundings, or
abiotic factors.
- biome- a group of ecosystems with the same climax communities; biomes on land are called terrestrial
biomes, those in water are called aquatic biomes.
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Abiotic factors such as precipitation and temperature determine the type of plant life there will be in a given
area. The plant life in turn determines the kind of animals that will live there.
-Recycling of materials in the Environment
The Carbon Cycle
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EOC Review 08-09
The Nitrogen Cycle
-symbiosis- living together of two dissimilar organisms for their mutual benefit. Ex: lichens are formed by a
symbiotic association between a fungus and an alga.
Types of symbiotic relationships
▪ Commensalism- helps one, doesn’t affect the other. Ex: cattle egret and grazing animals
▪ Mutualism- both benefit. Ex: flowers and their pollinators
▪ Parasitism- one benefits while the other is harmed. Ex: dog and heartworm
Review predator-prey relationships.
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POPULATION GROWTH
J curve – exponential growth - Under ideal conditions, (unlimited food
supply, no competition for mates, etc.) a population's size would continue to
increase indefinitely. This can be shown graphically and resembles the letter
J.
-S curve – logistic growth -In real populations size
cannot continue to increase indefinitely. It will increase
until carrying
capacity has been reached then it will level off.
-carrying capacity -the number of individuals of a
population that a given environment can support.
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EOC Review 08-09
-trophic levels - in an ecosystem, an organism's position in a food chain - for example, herbivores make up the
second trophic level and carnivores make up higher trophic levels.
Ex:
plant ---- mouse-------- snake---------owl------decomposer
(producer) (first order
(second order (third order
consumer)
consumer)
consumer)
FOOD WEB
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- pyramid of energy- each wlevel within a pyramid of energy represents the energy available within that
trophic level. Each time you move upward in the food chain there is roughly a 90% decrease in the amount of
available energy. This means each level contains only about 10% of the energy that was available at the
previous level.
-pyramid of numbers- a diagram that shows how many individuals an ecosystem can support.
-food web -a series of interrelated food chains in an ecosystem.
-biomass- total dried weight of all organic matter at different trophic levels.
-pyramid of biomass- shows how much living matter an ecosystem can support. Note the difference in the
characteristic shape of a terrestrial ecosystem versus an aquatic ecosystem.
algal bloom or algae bloom - explosive population increase in algae that occurs when large amounts of
phosphates and/or nitrates enter a body of water in the presence of warm temperatures.
-Phosphates are found in many detergents.
-Phosphates and nitrates are found in fertilizers
- Phosphates and nitrates serve as nutrients for algae. With lots of food and warm temperatures the algae
population increases extremely rapidly until they have used up all the available nutrients, then they begin to die
off very rapidly. As they die they settle to the bottom where they decompose. The decomposition process uses
up so much oxygen that there is not enough left for other organisms to carry out cellular respiration. As a result
they also begin to die. An entire lake may become stagnant as a result of an algae bloom.
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- acid precipitation caused by sulfur dioxide, SO2, which is produced when fossil fuels are burned. Can make
lakes and rivers too acidic for organisms to live in, kill trees, and corrode stone.
-ozone layer - found at the top of the stratosphere, the layer of ozone gas that absorbs almost all the Ultraviolet radiation that reaches the Earth from the sun. Many scientists think the ozone layer is thinning due to the
release of air pollutants known as CFC's (chlorofluorocarbons). CFC's are used as coolants in refrigerators and
air conditioners, in the manufacture of styrofoam, and as propellants in aerosol spray cans.
-greenhouse effect - results when carbon dioxide traps heat near the Earth's surface; could be producing global
warming, which may eventually have a serious effect on climate.
- biological magnification- the accumulation and increased concentration of non-biodegradable toxins in the
environment as you move up the food chain. Biological magnification of the pesticide DDT caused bald eagles
to become endangered.
Habitat destruction- is the process in which natural habitat is rendered functionally unable to support the
species originally present. In this process, plants and animals which previously used the site are displaced or
destroyed, reducing biodiversity. Agriculture is the principle cause of habitat destruction. Other important
causes of habitat destruction include mining, logging, trawling and urban sprawl. Habitat destruction is
currently ranked as the most important cause of species extinction worldwide.
Deforestation- The cutting down and removal of all or most of the trees in a forested area. Deforestation can
erode soils, contribute to desertification and the pollution of waterways, and decrease biodiversity through the
destruction of habitat.
ecological succession - gradual processes by which communities change over time.
primary succession - succession that begins in areas where there is no life such as a new volcanic island or an
area that has just been exposed due to the movement of a glacier.
pioneer stage - the first stage of primary succession, consisting of algae, protists, and cyanobacteria in an
aquatic community. Consists of lichens growing on bare rocks in a terrestrial (land) environment. The action of
the lichens and their subsequent death and decomposition lead to the formation of soil.
-Early stages in succession are characterized by communities with small inhabitants with short life cycles, few
different species, simple food chains, and wasted energy.
- The community continues to undergo an orderly series of changes until it reaches the final stage of succession.
climax community - the final community in ecological succession. The climax community is complex, stable,
and tends to remain basically the same unless disturbed by nature or humans. Climax communities are
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characterized by larger inhabitants with longer life cycles, many species, complex food webs, and efficient
energy use.
- Typical succession in a terrestrial biome: rock  lichen  mosses  grasses  shrubs  trees
Quadrant Study- a small portion of the entire area being studied (such as a 1 meter square quadrant) is marked
and all the organisms found there are documented. The counts taken in this area are then multiplied to
determine the likely number of individuals found in the entire study area.
POPULATIONS
Review factors influencing birth rates and death rates.
Effects of population size, density, and resources used on the environment.
- immigration- movement into a population.
- emigration- movement out of a population.
An introduced species (also known as an exotic species) is an organism that is not native to the place or area
where it is considered introduced and instead has been accidently or deliberately transported to the new location
by human activity. Introduced species can often be damaging to the ecosystem it is introduced to.
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-Estuaries- coastal body of water, partially surrounded by land, in which freshwater and saltwater mix.
-Estuaries are considered the most fertile of the aquatic environments and they exhibit a great deal of species
diversity.
-Salt concentrations in estuaries will vary.
Sustainable Practices/Stewardship
Sustainability- in recent years, has been expressed as “development that meets the needs of the present without
compromising the ability of future generations to meet their own needs”. Sustainable practices include the use
of alternative energy sources such as solar and wind power, recycling, and composting.
Environmental or ecological stewardship involves using sustainable practices and acting in an
environmentally friendly fashion.
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