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ECOLOGY – Chap 3

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I. General InfoA. Ecology is the study of the

interactions of living (biotic) organisms with their non-living (abiotic) environment.

What abiotic factor Is this orangutan interactingwith?

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B. Levels of Organization (smallest to largest)

1. Species - any organism that is able to interbreed and have fertile offspring

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2. Populations - groups of the same species living in the same area

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3. Communities - groups of populations (plants & animals) that live together in a defined area

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4. Ecosystem - the relationship of the community with its nonliving environment

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5. Biomes - ecosystems in different locations with similar climate and communities (e.g. desert, temperate forest, arctic, etc

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6. Biosphere - area on the planet where life exists (e.g. all biomes put together)

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Levels of organization

Ecosystem

Community

Population

Individual

Biome

Biosphere

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II. Energy Flow in a CommunityA. Producers (autotrophs) – Plants,

some algae. Photosynthesis is the main source of energy for life on earth

6CO2 + 6H2O → C6H12O6 + 6O2

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II. Energy Flow in a Community

B. Consumers (heterotrophs)1. Herbivores, carnivores, omnivores,

scavengers, and detritivores (feed on plant and animal remains, e.g. mites, earthworms, crabs)

2. Decomposers – break down dead organisms.

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C. Energy Transfer1. As organisms eat and in turn

are eaten, they transfer energy.2. This flow of energy travels in

one direction and is illustrated by a food chain or web.

3. Food Chaina. Almost always begins with a

plant or algae Why?

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3. Food Chain (cont)sun → producers → consumers

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4. Food Weba. Complex feeding relationship among

various organisms

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5. Food Pyramida. Each organism in the food chain/web

is placed in a different level called trophic levels.

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5. Food Pyramid (cont)b. Only 10% of energy is transferred to

organisms at next trophic level. Why?c. Total amount of living tissue in a given

trophic level is called the biomass.

5,000 grams of grain

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6. Biological Magnificationa. Some chemicals (DDT) and elements (lead

and mercury) cannot be burned or removed with the organism’s wastes.

b. They accumulate as you move up the food chain.

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III. Cycles of MatterA. The 4 most common elements found

in organisms are:

B. These elements are continuously recycled throughout the biosphere.

Hydrogen

Oxygen

Carbon

Nitrogen

H

O

N

C

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III. Cycles of Matter

Composition of Earth's Atmosphere

Nitrogen 78.1%Oxygen 20.9%

Argon 0.9%Carbon dioxide, Methane, inert

gases 0.1%

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C. The Water Cycle Process1. Water moves between the

ocean, atmosphere, and land.

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2. Water molecules enter the atmosphere as water vapor, a gas, when they evaporate from the ocean or other bodies of water.

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3. Water can also enter the atmosphere by evaporating from the leaves of plants in the process of transpiration.

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4. Water vapor condenses into tiny droplets that form clouds, and returns to Earth’s surface in the form of rain, snow, etc.

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D. Human Impacts on the Water Cycle.

1. Eutrophicationa. Fertilizers (N and P) run off

into freshwater ecosystems b.Explosive algal growthc. Ecosystem is drained of

nutrients and dissolved oxygen (DO)

What effect does this have on a lake?

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Eutrophication

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2. Acid Raina. Burning fossil fuels

produces SO2 and NOx.

b.They mix with water forming H2SO4 (sulfuric) and HNO3 (nitric) acids.

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Acid Rain

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2. Acid Rain Continuedc. This lowers the pH of the soil and

aquatic ecosystems. What are the effects of acid

rain?

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Long-term exposure to acid rain leaches nutrients from soil and makes plants vulnerable to nutrient

deficiencies.

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A forest devastated by acid rain in the Jizera mountains of the Czeck Republic

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III. Cycles of MatterE. The Carbon Cycle

1. Carbon is a key component of tissues in living organisms. Carbon is stored in the atmosphere (CO2 gas), oceans (dissolved CO2), organisms on land, & underground as coal/ petroleum).

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Carbon CycleCO2 in Atmosphere

Photosynthesis

feeding

feeding

Respiration

Deposition

Carbonate Rocks

Deposition

Decomposition

Fossil fuel

Volcanic activity

Uplift

Erosion

Respiration

Human activity

CO2 in Ocean

Photosynthesis

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2. There are 4 main processes that move carbon through its cycle:a. Biological processes -

(photosynthesis, respiration, & decomposition) take up & release carbon & oxygen. Plants take in the CO2, & convert it to carbohydrates which are passed through the food web to consumers.

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b. Geochemical processes – (erosion & volcanic activity) release carbon dioxide to the atmosphere & oceans.

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c. Storage – carbon is stored underground as coal, oil, & natural gas. Dead organisms are buried & eventually converted through heat & pressure to coal & oil (fossil fuels).

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d. Carbon release – human activities such as clear cutting forests, mining, burning forests, & burning gas & oil release CO2 into the atmosphere.

Clearcut by Weyerhaeuser in Oregon.

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E. The Carbon Cycle cont.3. Global Warming “Greenhouse Effect”

a. Caused by the accumulation of excess CO2 in the atmosphere

What are some sources of the CO2?

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3. Global Warming “Greenhouse Effect” (cont)b. CO2 and other gases warm the surface

of the planet naturally by trapping solar heat in the atmosphere (draw)

sunlight Some heat escapes into space

Greenhouse gases trap some heat

atmosphere

What kind of problems can this cause?

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NASA Surface Temperature Analysis

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Between 1979 – 2003 Arctic perennial sea ice has been decreasing at 9% per

decade.

Arctic sea ice cover 1979. Arctic sea ice cover 2003.

Credit: NASA Goddard Space Flight Center.

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F. The Nitrogen Cycle1. All organisms require nitrogen to

make proteins.a. Only certain types of bacteria can

use nitrogen gas directly.b. Nitrogen fixation – Some bacteria

in the soil and on the roots of plants called legumes (black beans, kidney beans, lima beans) convert nitrogen gas into ammonia (NH3).

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Nitrogen Cycle (draw)

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Nitrogen Cycle

Bacterial nitrogen fixation

N2 in Atmosphere

NH3

Synthetic fertilizer manufacturer

Uptake by producers

Reuse by consumers

Decomposition excretion

Atmospheric nitrogen fixation

Uptake by producers

Reuse by consumers

Decomposition

Decomposition excretion

NO3 and NO2

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2. Other bacteria in the soil convert ammonia (NH3) into nitrates (NO3-) and nitrites (NO2-) which are used by producers to make proteins.

3. Consumers then eat the producers and reuse the nitrogen to make their own proteins.