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Chapter 4Matter and Energy in

the Ecosystem

Ecosystems transfer energy!

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Section 4.1: Roles of Living Things

PRODUCERS - also known as Autotrophs• Organisms that make their own food from

inorganic molecules and energy.• Plants are the most familiar.• Almost all capture energy from the sun and

make food through photosynthesis.• Photosynthesis Formula: Sunlight energy + H2O + CO2 = C6H12O6(food) + O2

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CONSUMERS – also known as heterotrophs• Organisms that cannot make their own food.• This includes all animals, fungi and many

protists (single-celled organisms) and bacteria.• Four basic kinds of consumers.

oHerbivores – eat plantsoCarnivores – eat meat (herbivores &

carnivores)oOmnivores – eat producers & consumersoScavengers – eat dead organisms

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HERBIVORE

CARNIVORE

OMNIVORE

SCAVENGER

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DECOMPOSERS – also known as heterotrophs• Bacteria & fungi that consume the bodies of

dead organisms and other organic wastes. • They consume leaves fallen from trees to

bodies of dead herbivores and carnivores.• Bacteria and fungi break down organic matter

in animal waste.• Decomposers are beneficial to an ecosystem

because they recycle nutrients from organisms back into the environment to be used again.

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TROPHIC LEVELS• A layer in the structure of feeding relationships in

an ecosystem.• Producers make up the first and largest trophic

level, they make their own food so they are called autotrophs. (at the bottom)

• Consumers make up several more trophic levels, because they cannot make their own food they are called heterotrophs.

• Decomposers – are on the top. Break everything back down into the earth.

• Most ecosystems have 3, 4, or 5 trophic levels.• Humans exist at any trophic level except the first.

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Section 4.2 Ecosystem Structure

Food Chains and Food Webs• Energy moves through ecosystems in the

form of food.• Food chain – a series of different organisms

that pass food between the trophic levels.• Food web – a network of food chains

representing the feeding relationships among organisms.

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Biological Magnification• The effects of pollution by humans can be

magnified in a food web.• The pesticide DDT was passed through a food

web• It was sprayed on crops to kill insects

• DDT washed into lakes and streams by rain and was taken in by producers.

• The DDT passed through consumers and caused problems in reproduction decreasing the population of bald eagles greatly.

• Humans are particularly vulnerable to toxic pollutants because of biological magnification.

Section 4.2 Ecosystem Structure

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• BIOMASS• Energy in the form of

biomass is transferred through the ecosystem as one trophic level feeds on another.

• Biomass – is the total amount of organic matter present in a trophic level.

• Biomass pyramids depict the mass of organic matter in each trophic level.

Section 4.3 Energy in the Ecosystem

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About 96% of your body is made up of just 4 elements:Carbon (C)Hydrogen (H)Nitrogen (N)Oxygen (O)

These 4 elements are also essential to the growth of producers in an ecosystem.

Section 4.4 Cycles of Matter

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WATER CYCLE• Water moving between the ocean, atmosphere and

land.• The sun is the source of energy that powers the

cycle.• Evaporation – water changes from a liquid to a

gas and enters the atmosphere.• Transpiration – the evaporation of water from the

leaves of plants into the atmosphere.• Condensation - Water vapor cools as it rises and

condenses into tiny droplets, forming clouds.• Precipitation – water returns to the earth’s

surface as rain, snow, sleet or hail.

Section 4.4 Cycles of Matter

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Scientists estimate that it can take a water molecule that falls on land 4,000 years to complete the cycle

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CARBON CYCLE• The reactions of 2 primary processes of

photosynthesis and cellular respiration could not occur without carbon.

• Photosynthesis o Sunlight energy + H2O + CO2 = C6H12O6(food) +

O2

• Cellular Respiration o C6H12O6(food) + O2 = CO2 + H2O + energy

• 2 other important sources of carbon are the ocean and rocks.

• CO2 dissolves easily in water.

• Carbon also stored in rocks like coal, limestone, oil.

Section 4.4 Cycles of Matter

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• NITROGEN CYCLE• Organisms require nitrogen which

is a key element in the formation of amino acids.

• Amino Acids are the building blocks of protein.

• Certain type of bacteria use nitrogen gas directly from the atmosphere.

• Without bacteria, living things would not be able to utilize nitrogen.

• Such nitrogen-fixing bacteria produce ammonia (NH3), a form of nitrogen plants can use.

Section 4.4 Cycles of Matter

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• Nitrogen fixing bacteria live both in the soil and in the roots of legumes.

• Legumes include peanuts, beans, and clover.• Legumes enrich the soil by adding nitrogen to it

through their root nodules.• Animals get nitrogen by eating the plants with

the protein or other consumers• Decomposers return nitrogen to the soil and

the cycle starts again.

Section 4.4 Cycles of Matter

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