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Ecosystems and Biomes

Chapter 2

Section 1: Energy in Ecosystems

Energy Roles in the Ecosystem

� Producers

� Consumers

� Decomposers

Producers

� Plants

� Capture energy from the sun

� Main source of all the energy in an ecosystem

Consumers (3types)

� Herbivores- eat plants only (first level consumers)

� Omnivores- eat both plants and animals

� Carnivores- eat animals only

� Scavengers – a carnivore that feeds on dead animals

Decomposers

� Bacteria and fungi that decay (break down) dead organisms and return material to the soil

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Food Chain

� A sequence of events in which food energy is passed from one individual to another

Food Webs

� Ecosystems have many food chains

� An animal in one food chain often eats animals in other food chains

� When food chains overlap, it is called a food web

Energy Pyramid (energy flow)

� 1% of the sun’s energy is used by plants to make food

� Most of this energy is used up by the plant (only small amount stored)

� This energy is passed on to primary consumer who uses most of this energy (only 10% passed on)

� At each level of the pyramid, the amount of energy available decreases

Section 2: Cycles of Matter

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Water Cycle

� Evaporation, condensation, precipitation

� Transpiration- water vapor from plants

� Percolation- water seeping into ground

� Runoff

Carbon-Oxygen Cycle

� organisms need oxygen to release energy from their food (respiration)

� carbon dioxide is needed by plants to make food (photosynthesis)

� animals take in O2 and give off CO2

� plants take in CO2 and give off O2

� CO2 is given off when dead plants and animals decompose

Nitrogen Cycle

� Nitrogen-fixing bacteria in plant roots change N2 from the air into a form of nitrogen (NO3

-) plants can use

� The nitrogen becomes part of the plant.

� The nitrogen becomes part of the animal when the animal eats the plant

� Decomposers break down dead plants and animals and nitrogen is returned to the soil.