bellringer you are trying to stop world hunger. on your quest to do so, you choose to provide food...
TRANSCRIPT
Bellringer
You are trying to stop world hunger. On your quest to do so, you choose to provide food for a third world country.
Which would be ideal to provide: grains or meat? Why?
Energy Transformation
What is an ecosystem?
• An ecosystem consists of– all the organisms in a community and– the abiotic environment with which the
organisms interact.
• In an ecosystem,• energy flow moves through the components
of an ecosystem and• chemical cycling is the transfer of materials within the ecosystem.
A TerrariumA terrarium represents the components of an ecosystem and
illustrates the fundamentals of energy flow.
Lightenergy
Chemicalenergy
Energy flow
Chemicalelements
Heatenergy
Bacteria,protists,and fungi
Primary production sets the energy budget for ecosystems
• Primary production– carried out by producers
– is the amount of solar energy converted to chemical energy by an ecosystem’s producers for a given area and during a given time period
– produces biomass, the amount of living organic material in an ecosystem
• Different ecosystems vary in their– primary production and
– contribution to the total production of the biosphere.
© 2012 Pearson Education, Inc.
Figure 37.15
Open ocean
Estuary
Algal beds and coral reefs
Desert and semidesert scrub
Tundra
Temperate grassland
Cultivated land
Boreal forest (taiga)
Savanna
Temperate deciduous forest
Tropical rain forest
0 500 1,000 1,500 2,000 2,500
Average net primary productivity (g/m2/yr)
Figure 37.16A
Plant materialeaten by caterpillar
100 kilocalories (kcal)
50 kcal35 kcal
15 kcalFeces
Cellularrespiration
Growth
50% is eliminated in feces,35% is used in cellular respiration15% is used for growth.
Why do food chains and webs typically have only
three to five levels?
Energy supply limits the length of food chains
• A pyramid of production shows the flow of energy– from producers to primary consumers and to
higher trophic levels
© 2012 Pearson Education, Inc.
Only about 10% of the energy stored at each trophic level is available to the
next level.
Figure 37.16B
Tertiaryconsumers
Secondaryconsumers
Primaryconsumers
Producers
10 kcal
100 kcal
1,000 kcal
10,000 kcal
1,000,000 kcal of sunlight
Energy comes in the form of CALORIES here.
CONNECTION: A pyramid of production explains the ecological cost of meat
• When humans eat…
– grain or fruit primary consumers
– beef or other meat from herbivores secondary consumers
– fish like trout or salmon tertiary or quaternary consumers
© 2012 Pearson Education, Inc.
Figure 37.8_s5 Trophic level
Plant
A terrestrial food chain An aquatic food chain
ProducersPhytoplankton
GrasshopperPrimary
consumers Zooplankton
MouseSecondaryconsumers Herring
TunaSnake
Tertiaryconsumers
Killer whaleHawk
Quaternaryconsumers
• Only about 10% of the chemical energy available in a trophic level is passed to the next higher trophic level.
• Therefore, the human population has about ten times more energy available to it when people eat plants instead of the meat of herbivores.
• Eating meat of any kind is expensive both economically and environmentally
© 2012 Pearson Education, Inc.
Figure 37.17_1
Trophic level
Vegetarians
Corn
Primaryconsumers
Secondaryconsumers
Producers
Figure 37.17_2
Corn
Cattle
Meat-eaters
Trophic level
Primaryconsumers
Secondaryconsumers
Producers
Chemicals are cycled between organic matter and abiotic reservoirs
• Ecosystems are supplied with a continual influx of energy from the sun and Earth’s interior.
• Except for meteorites, there are no extraterrestrial sources of chemical elements.
• Thus, life also depends on the recycling of chemicals.
© 2012 Pearson Education, Inc.
• Biogeochemical cycles include– biotic components– abiotic components (non-living factors i.e. water)– abiotic reservoirs, where a chemical
accumulates or is stockpiled outside of living organisms
• Biogeochemical cycles can be– local or– global.
Biogeochemical Cycles
© 2012 Pearson Education, Inc.
Exit Slip
Thinking back on our primary production graph, what explains
why tropical rain forests were among the highest contributors?
End of Class/HomeworkEnd of Class/Homework
In your textbook, read pages 752 (starting with
section 37.18) to 756.
Be sure to add any “new” words to your vocabulary list.