copyright © 2003 pearson education, inc. publishing as benjamin cummings trophic levels and food...
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Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Trophic Levels and Food Chains
• Food Chain:
– set of food (energy) transfer from trophic level to trophic level
Figure 19.21
Carnivore
Carnivore
Carnivore
Herbivore
Plant
A terrestrial food chain
Quaternary consumers
Tertiary consumers
Secondary consumers
Primary consumers
Producers
Carnivore
Carnivore
Carnivore
Zooplankton
Phytoplankton
A marine food chain
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Herbivores: eat plants, algae, or autotrophic bacteria, are the primary consumers of an ecosystem
• Carnivores, which eat the consumers from the levels below
– Secondary consumers include many small mammals, such as rodents, and small fishes that eat zooplankton
– Tertiary consumers, such as snakes, eat mice and other secondary consumers
– Quaternary consumers include hawks and killer whales.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Decomposers:
– What is a decomposer and what do they do? What trophic level would you put them at?
– Derive their energy from the dead material left by all trophic levels
– Are often left off of most food chain diagrams
Figure 19.22
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Figure 19.23
Quaternary,
tertiary,
and secondary consumers
Tertiary and
secondary consumers
Secondary and
primary consumers
Primary consumers
Producers (plants)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• When energy flows as organic matter through the trophic levels of an ecosystem, much of it is lost at each link in a food chain. Why?
• When you burn energy to run down the mile in gym what happens to most of the energy you are using?
Energy Pyramids
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Figure 19.25
Plant material eaten by caterpillar
100 kilocalories (kcal)
50 kcalFeces
15 kcal
Growth
35 kcalCellular respiration
Does all the energy this caterpillar eats get passed to the bird who eats him?
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Energy pyramid
– Is a diagram that represents the cumulative loss of energy from a food chain
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 19.26
Tertiary consumers
Secondary consumers
Primary consumers
Producers
10 kcal
100 kcal
1,000 kcal
10,000 kcal
What happens to energy as you go up trophic levels? Why?
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Ecosystems
CHEMICAL CYCLING IN ECOSYSTEMS
– Depend on a recycling of chemical elements
– What gets recycled in our ecosystem?
• Energy?? NOOO
• Water
• Carbon
• Phosphorus
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Generalized scheme for biogeochemical cycles
Figure 19.28
Consumers
Producers
Detritivores
Nutrients available to producers
Abiotic reservoir
Geologic processes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 19.29a
CO2 in atmosphere
Burning
Wood and fossil fuels
Cellular respiration
Higher-level consumers
Decomposition
Detritivores
Photosynthesis
Producers
Primary consumers
Detritus
(a) The carbon cycle
• The carbon cycle
What do we eat that has carbon?
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Carbon Cycle
• Producers: Plants take in CO2 and make sugar by photosynthesis.
• Consumers: Animals eat plants to get energy (respiration) from sugar and make proteins from the carbon.
– Breath out CO2 as a waste product of respiration.
• Animals die and dentritus (decomposers) break down the carbon and other elements back into the soil and air for plants to use again.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 19.29b
Denitrifying bacteria Assimilation
by plants
Nitrogen (N2) in atmosphere
Amino acids and proteins in plants and
animals
Detritus
Detritivores
Nitrogen-fixing bacteria
in root nodules of legumesDecomposition
Nitrogen fixation Nitrogen-
fixing bacteriain soil
Ammonium (NH4
+ )Nitrifying bacteria
Nitrates (NO3
– )
• The nitrogen cycle
(b) The nitrogen cycle
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Nitrogen Fixation by bacteria
• Plants need nitrogen but cannot take it in from the air.
• Bacteria in the soil on the roots of plants take in nitrogen (N2) and make ammonia (NH4) which plants can then use to get nitrogen.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 19.29c
• The phosphorous cycle Uplifting
of rockPhosphates
in rock
Weathering of rock
Phosphatesin organic
compoundsConsumers
Producers
Rock
Precipitated (solid)
phosphatesPhosphates in solution
Phosphatesin soil
(inorganic)
Detritus
Detritivores in soil
(c) The phosphorus cycle
What part of you has phosphate?
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The water cycle
Figure 19.29d
Precipitation over the sea
(283)
Solar heat
Water vapor over the sea
Oceans
Net movement of water vapor by wind (36)
Evaporation from the sea (319)
Evaporation and transpiration (59)
Water vapor over the
land
Precipitation over the land (95)
Surfacewater and
groundwater
Flow of water from land to sea
(36)
(d) The water cycle
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