BIG IDEA:

WHAT HAPPENS TO ENERGY STORED IN BODY TISSUES WHEN ONE ORGANISM

EATS ANOTHER?

Energy Flow In Ecosystems

Food Chains & Food Webs

How does energy flow through ecosystems? A 1-way stream, from

primary producers to consumers

Food Chains A series of steps in which

organisms transfer energy by eating and being eaten

Food Chains & Food Webs

Food Webs A network of feeding relationships; shows all the

feeding relationships within an ecosystem

Food Chains & Food Webs

Food Webs – Very complicated

Notebook Time: Describe the ecosystem that is your backyard Draw a food web of that ecosystem

Be as specific as possible Draw a food chain from within your food web What role do decomposers & detritivores play in food

webs?

Food Chains & Food Webs

Disturbances In your groups, answer the following questions using

the food web below: What effect would an insecticide have on the food web? Would this have an effect on the populations of non-insect

eating animals? What populations would increase? What populations would decrease? Would this change any animals

eating habits? Which ones & how?

Trophic Levels & Ecological Pyramids

Trophic Level Each step in a food chain

Ecological Pyramids Show relative amount of energy or matter contained

within each trophic level in a given food chain or food web

There are 3 different types of Ecological Pyramids Pyramids of Energy Pyramids of Biomass Pyramids of numbers

Ecological Pyramids

Pyramids of Energy Show relative amounts

of energy available at each trophic level

Typically 1/10 or 10% of available

energy within one trophic level is passed on to the next level

In other words: 1/10 of the solar

energy captured and stored in leaves of grasses ends up stored in the tissues of cows

Ecological Pyramids

Pyramid of Biomass & Numbers Biomass –

Total amount of living tissue within a given trophic level

Pyramid of Biomass Illustrates the relative

amount of living organic matter available at each trophic level of an ecosystem

Ecological Pyramids

Pyramid of Biomass & Numbers Pyramid of Numbers

Shows the relative number of individual organisms at each trophic level in an ecosystem

Cycles of Matter

How does matter move through the biosphere? Biogeochemical cycles

Elements pass from one organism to another and among parts of the biosphere in closed loops

These loops are powered by the flow of energy.

4 Processes involved with biogeochemical cycles Biological Processes

Any and all activities performed by living organisms Geological Processes

Volcanic eruptions, erosion, plate tectonics Chemical & Physical Processes

Formation of clouds, flow of running water, lightning Human Activity

Deforestation, burning of fossil fuels, use of fertilizers

Water Cycle

Water moves continuously between, oceans, the atmosphere, land and the organisms in them.Transpiration

Evaporation of water from leaves of the plantsEvaporation

Loss of water from surface of bodies of waterCondensation

When water vapor cools & becomes liquidPrecipitation

When water falls out of the atmosphere

Nutrient Cycles

3 main Nutrient Cycles Carbon Nitrogen Phosphorus

Nutrient Cycles

Carbon Cycle Found in several large reservoirs in biosphere

Atmosphere = CO2 Oceans = Dissolved CO2 Land = in organisms, soil & rocks Underground =

Coal, Petroleum & Calcium Carbonate In Life = base of all organic molecules

Nutrient Cycles

Nitrogen Cycle Required to build proteins, DNA, RNA Atmospheric Nitrogen

N2 = Non-usable form for most organisms Needs to be “fixed” Nitrogen Fixation

• Process of N2 being converted into ammonia, nitrates & nitrites by bacteria

• Relatively small amounts of N2 can be fixed by Lightning Denitrification

• When N2 is released by soil bacteria who use nitrates for energy Fertilizer

Huge human influence in adding excess Nitrates & Nitrites into aquatic ecosystems Can cause algal blooms

Nutrient Cycles

Phosphorus Cycle Essential for creation of DNA, RNA Not very abundant in biosphere

Remains mostly on land in rock, soil, & sediments As rock & sediments wear down, P is released to

environment.

Nutrient Cycles

Nutrient Limitation Limiting Nutrient

The nutrient whose supply limits productivity

In Soil Typically Limiting Nutrients are:

Ca, Mg, S, Fe, Mn, P, Fixed N, In Ocean

Typically Limiting Nutrients are: Fixed N