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3–1 What Is Ecology? Pages 63 - 65A. Interactions and

InterdependenceB. Levels of OrganizationC. Ecological Methods

1. Observing2. Experimenting3. Modeling

Section 3-1

Section Outline

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3.1 What Is Ecology?

Interactions & Interdependence*Ecology is the study of interactions among organisms and between organisms and their environment*Biosphere- contains the combined portions of the planet in which all of life exists, including land, water and air, or atmosphere; extends 8 kilometers above Earth’s surface to as far as 11 km below the surface of the ocean*Interactions within the biosphere produce a web of interdependence between organisms and the environment in which they live.

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Levels of Organization

*Some ecologists study interactions between a particular kind of organism and its surroundings.

*Species- a group of organisms so similar to one another that they can breed and produce fertile offspring.

*Populations- groups of individuals that belong to the same species and live in the same area.

*Communities- assemblages of different populations that live together in a defined area

*Ecologists may study a particular ecosystem- collection of all the organisms that live in a particular place together with their nonliving environment.

*Biomes are groups of ecosystems that have the same climate and similar

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dominant communities.*Regardless of the tools they use, scientists conduct modern ecological

research using three basic approaches: observing, experimenting, and modeling.

*Observing- 1st step in asking questions*Experimenting- used to test hypotheses; some are conducted in labs,

some in natural ecosystems*Modeling- gives insight into complex phenomena such as the effects of

global warming on ecosystems

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Section 3-1

Figure 3-2 Ecological Levels of Organization

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3–2 Energy FlowA.Producers

1. Energy From the Sun2. Life Without Light

B.ConsumersC.Feeding Relationships

1. Food Chains2. Food Webs3. Trophic Levels

D.Ecological Pyramids1. Energy Pyramid2. Biomass Pyramid3. Pyramid of Numbers

Section 3-2

Section Outline

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Section 2 Energy Flow

One of the most important factors that determine whether an ecosystem can sustain life.

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3-2A. Producers

Autotrophs – use energy from the environment to make their own food.Sunlight is the main energy source for life on Earth.Chemical energy – Mineral water flowing underground can release energy needed by some organisms.

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A-1 Energy from the sun

a. Photosynthesis – uses light energy to power chemical reactions that convert CO2 and H2O into oxygen and energy rich carbohydrates such as sugars and starches.

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A-1 Continued

2. Land – plants are the main autotrophsFreshwater – algaeWet ecosystems – cyanobacteria

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A-2 Life without Light

Chemosynthesizers – use chemical energy to produce carbohydrates.(Deep sea vents)

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3-2B. Consumers

1.Obtain energy from other organisms because they cannot produce their own energy.

2.Heterotrophs – organisms that must rely on other organisms for their food and energy supply

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Continued….

Types of Heterotrophs:a.Herbivores – eat only plants; cow, deerb.Carnivores – eat only animals; snakes,

owls, dogsc.Omnivores – eat both plants and

animals; humans, bears, crows

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continued

d. Detritivores – eat plant and animal remains and other dead matter (detritus); mites, earthworms, snailse. Decomposers – break down organic matter; fungus & bacteria

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3-2C Feeding Relationships

Introduction:Energy is a one way path from the sun to autotrophs to heterotrophs1. Food chains – a series of steps in which organisms transfer energy by eating and being eaten

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C-2 Food Webs

Show more complex feeding relationships; more realisticLinks all food chains in an ecosystem together

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Section 3-2

Figure 3-8 A Food Web

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C-3 Trophic Levels

a.Each step in a food chain or webb.Producers always make up the first

trophic levelc.Consumers make up the second, third,

fourth, etc.d.Each consumer depends on the trophic

level before it for energy

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3-2D Ecological Pyramids

Introduction:A diagram that shows the relative amount of energy or matter contained within each trophic level in a food chain or food web.

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D-1 Energy Pyramid

Only about 10% of the energy in the previous tropic level is transferred to the next level. The energy is used for life processes such as growth, reproduction, and movement. (lost as heat)Usually because the organisms are bigger and harder to maintain.

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D-2 Biomass Pyramid

Biomass – the total amount of living tissue within a given trophic levelIt represents the amount of potential food available for each trophic level in an ecosystem.

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D-3 Pyramid of Numbers

Number of individual organisms at each trophic level.

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3–3 Cycles of MatterA. Recycling in the BiosphereB. The Water CycleC. Nutrient Cycles

1. The Carbon Cycle2. The Nitrogen Cycle3. The Phosphorus Cycle

D. Nutrient Limitation

Section 3-3

Section Outline

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Condensation

Seepage

Runoff

Precipitation

TranspirationEvaporation

RootUptake

Section 3-3

The Water Cycle

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CO2 inAtmosphere

CO2 in Ocean

Section 3-3

Figure 3-13 The Carbon Cycle

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N2 in Atmosphere

NH3

NO3-

and NO2-

Section 3-3

Figure 3-14 The Nitrogen Cycle

Video

Click the image to play the video segment.

Cycles in Nature

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3.3 Cycles of Matter

1. More than 95% of an organism’s body is made up of oxygen, carbon, hydrogen, and nitrogen

*RECYCLING IN THE BIOSPHERE1. Unlike the one-way flow of energy, matter is recycled within and

between ecosystems.2. Elements, chemical compounds, and other forms of matter are passed

from one organism to another and from one part of the biosphere to another through biogeochemical cycles.

3. Matter can cycle through the biosphere because biological systems do not use up matter, they transform it.

4. Biogeochemical cycles pass the same molecules around again and again within the biosphere.

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The Water Cycle

1. All living things require water to survive.2. Water molecules enter the atmosphere as water vapor when they

evaporate from the ocean or other bodies of water.3. The process by which water changes from liquid form to an atmospheric

gas is called evaporation.4. Water can also enter the atmosphere by evaporating from the leaves of

plants in the process of transpiration.5. Sun heats atmosphere during the day.6. As warm air rises, it cools.7. Water vapor condenses into droplets that form clouds.8. When droplets become large enough, they return to Earth’s surface in

the form of precipitation.

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9. On land, much of the precipitation runs along the surface of the ground until it enters a river or stream that carries runoff back to an ocean or lake.

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Nutrient Cycles

• All the chemical substances that an organism needs to sustain life are its nutrients.

• Nutrients are needed for: building tissues and carrying out essential life functions

• Nutrients are passed between organisms and the environment through biogeochemical cycles

• The Carbon Cycle- carbon is a key ingredient in living tissue- in the form of calcium carbonate, carbon is an important component of animal skeletons and is found in different rocks.

CO2 is taken in by plants during photosynthesis and is given off by both plants and animals during respiration

• 4 main types of processes move carbon through its cycle:

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1. Biological processes, such as photosynthesis, respiration, and decomposition take up and release carbon and oxygen

2. Geochemical processes, such as erosion and volcanic activity, release carbon dioxide to the atmosphere and oceans.

3. Mixed biogeochemical processes such as the burial and decomposition of dead organisms and their conversion under pressure into coal and petroleum, store carbon underground.

4. Human activities such as mining, cutting and burning forests, and burning fossil fuels, release carbon dioxide into the atmosphere.

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• In the atmosphere, carbon is present as CO2. *CO2 is released into the atmosphere by volcanic activity, by respiration, by human activities and by decomposition.

• Plants take in CO2 and use the carbon to build carbs during photosynthesis.

• Carbs passed along food webs to animals.• In the ocean, carbon is found in the form of calcium carbonate, which is

formed by marine organisms.• Accumulates as a chalky substance in the bones and shells of

organisms.• Compounds break down and the carbon returns to the atmosphere.

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The Nitrogen Cycle

• All organisms require nitrogen to make amino acids, which in turn are useful to build proteins

• N2 makes up 78% of Earth’s atmosphere.• NH3 (Ammonia), nitrate ions, and nitrite ions are found in wastes

produced by many organisms• Plant fertilizers add nitrogen to the biosphere• Nitrogen gas is the most abundant form of nitrogen on Earth• Only certain bacteria can use this form of nitrogen directly• Some bacteria convert nitrogen gas into ammonia by nitrogen fixation• When organisms die, decomposers return nitrogen to the soil as ammonia• Other soil bacteria convert nitrates into nitrogen gas by

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dentrification.

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The Phosphorus Cycle

1. Phosphorus- impt in the formation of DNA and RNA2. Not common in the biosphere3. Does not enter the biosphere4. Remains mostly on land in rock and soil minerals5. Exists as inorganic phosphate6. As rock and sediment wear, phosphate is released7. Washes into rivers and streams where it dissolves; some makes its way

to the oceans, where it is used by some marine organisms8. Some phosphate stays on land and cycles between organisms and the

soil.9. When plants absorb phosphate form the soil or from water, the plants

bind the phosphate into organic compounds.

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Nutrient Limitation

1. Primary Productivity- rate at which organic matter is created by producers; controlled by the amount of available nutrients; limiting nutrient- when an ecosystem is limited by scarce nutrients

2. Fertilizers containing nitrogen, phosphorus, and potassium are added to crops to boost productivity.

3. When an aquatic ecosystem receives a large input of a limiting nutrient, the result is often an immediate increase in the amount of algae and other producers- algal bloom

Interest Grabber Answers

1. What living things are found in and around your school?Living things in the school are students, teachers, principal, assistant principals, clerical staff, custodians, lunchroom staff. Students may also include animals in science labs. Living things around the school include grass, trees, shrubs, insects, birds, and so on.

2. What nonliving things are found in your school?The building, furniture, desks, books, papers, and so on

3. Into what large groups are the students in your school divided?9th, 10th, 11th, 12th grades, or years

4. Into what smaller groups are these large groups divided?Classes

5. Are these groups ever divided into even smaller groups? If so, what are these groups?Students may say that science classes are divided into lab groups; other classes may be divided into groups for projects.

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Interest Grabber Answers

1. Make a list of five foods that you like to eat. Indicate whether the food comes from a plant (producer) or an animal (consumer). Student lists will be individualized. One possible example would be a hamburger, which comes from a cow or steer.

2. Like many birds, chickens eat grains, which are seeds. Where do seeds come from?Seeds come from plants.

3. Meat comes from beef cattle. What do cattle eat?Cattle eat grass or grains.

4. Construct a diagram showing how one of your favorite foods obtains its energy. Include as many levels as you can.Student diagrams will be individualized based on their food choice. Using the hamburger example, the beef in the hamburger comes from cattle. The cattle feed on grass or grain. Grass or grains are plants, which use energy from the sun to make their own food.

Interest Grabber Answers

1. When rain falls on the ground, it either soaks into the soil or runs across the surface of the soil. When rainwater runs across the land, what body of water might collect the rain?Possible answers: a stream, river, pond, or lake

2. From here, where might the water flow?Into a river, and eventually into the ocean

3. After the rain, the sun comes out and the land dries. Where does the water that had been on the land go?It evaporates and becomes a gas in the atmosphere.

4. Construct a diagram that would illustrate all the places a molecule of water might go. Begin with a raindrop and end with a cloud.Student diagrams may include the following: a raindrop —> lawn —> a stream —> river —> large lake —> atmosphere —> cloud.