1. 2.1 Energy Flow in Ecosystems
___________is the total mass of all living things in a given area.
Biomass can also refer to the mass of a particular type of ___________, such as organic materials used to produce biofuels.
Biomass is generally measured in g/m2 or kg/m2 .
Within an organism’s ___________, the organism interacts with the ecosystem by:
Obtaining ___________from the ecosystem
Contributing ___________to the ecosystem
___________are called producers because they produce
carbohydrates from carbon dioxide, water, and the Sun’s energy.
___________get their energy by feeding on producers or other consumers.
___________is the breakdown of wastes and dead organisms by organisms called decomposers through the process of biodegradation.
Bees are consumers.
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2. Energy Flow and Energy Loss in Ecosystems: Food Chains
Scientists use different methods to represent ___________moving through ecosystems.
Food chains
Food webs
Food pyramids
Food chains show the flow of
___________in an ecosystem.
Each step in a food chain is a ___________level
___________= 1st trophic level
___________consumers = 2nd trophic level
___________consumers = 3rd trophic level
___________consumers = 4th trophic level
Examples of terrestrial and aquatic food chains
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3. Energy Flow and Energy Loss in Ecosystems: Food Chains (continued)
___________in a food chain can be classified as:
___________– consumers that obtain energy and nutrients from dead organisms and waste matter
Examples include earthworms, bacteria and fungi.
Detrivores feed at every trophic level.
Detrivores have their own, separate food chains
and are very numerous.
___________– primary consumers
Herbivores eat plants (producers) only.
___________– secondary or tertiary consumers
Secondary consumers eat non-producers, such as herbivores.
Tertiary consumers eat secondary consumers.
Also called top consumers or top carnivores.
___________– consumers that eat both plants and animals
Examples include humans and bears.
This dung beetle is a detrivore.
See page 61
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4. Energy Flow and Energy Loss in Ecosystems: Food Webs
Most organisms are part of many food ___________.
Food ___________represent interconnected food chains.
Food webs are models of the feeding relationships in an ___________.
Arrows in a food web represent the flow of ___________and nutrients.
Following the arrows leads to the ___________carnivore(s).
This food web represents a terrestrial ecosystem that could be found in British Columbia.
See page 62
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5. Energy Flow and Energy Loss in Ecosystems: Food Pyramids
Food ___________show the changes in available energy from one trophic level to another in a food chain.
Energy enters at the first trophic level (___________), where there is a large amount of biomass and therefore much energy.
It takes large quantities of organisms in one trophic level to meet the energy needs of the next trophic level.
Each level loses large amounts of the ___________
it gathers through basic processes of living.
80 – 90 percent of energy taken in by consumers
is used in ______________________in the body
and is lost as thermal energy.
There is very ___________energy left over for growth or increase in biomass.
Ninety percent of this mouse’s food energy is used to maintain its life functions.
See page 63
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6. Energy Flow and Energy Loss in Ecosystems: Food Pyramids (continued)
Food pyramids are also known as ___________pyramids.
Ecological pyramids may show biomass, population, or energy numbers.
The amount of life an ecosystem can contain is based on the bottom level of the ecological pyramid, where producers capture energy from the ___________.
Each level in the energy pyramid = a loss of ___percent of total energy available.
Lower trophic levels have much
larger populations than upper levels.
This shows the importance of
maintaining large, biodiverse
populations at the ___________levels
of the food pyramid.
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Take the Section 2.1 Quiz
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7. 2.2 Nutrient Cycles in Ecosystems
____________ are chemicals required for growth and other life processes.
Nutrients move through the biosphere in ____________ or exchanges.
Nutrients often accumulate in areas called ____________ .
Without interference, generally the amount of nutrients flowing into a store equals the amount of nutrients flowing out.
Human activities can upset the natural ____________ of nutrient cycles.
Land clearing, agriculture, urban expansion, mining, industry, and motorized transportation can all increase the levels of nutrients more quickly than the stores can absorb them.
Excess nutrients in the biosphere can have unexpected consequences.
There are five chemical ____________ required for life.
Carbon, hydrogen, oxygen, and nitrogen cycle between living things and the atmosphere.
Phosphorus cycles in from sedimentary rock.
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8. Nutrient Cycles: The Carbon Cycle
____________ atoms are a fundamental unit in cells of all living things.
Carbon is also an essential part of chemical processes that sustain life.
Carbon can be stored in many different ____________ .
Short-term shortage is found in aquatic and terrestrial organisms,
in CO2 in the atmosphere and in the top layers of the ocean.
Long-term storage is found in middle and lower ocean layers as dissolved CO2 and in coal, oil, and gas deposits in land and ocean sediments.
Sedimentation ____________ many long-term stores of carbon.
Layers of soil and decomposing organic matter become buried
on land and under the oceans.
Slowly, under great pressure over many years, coal, oil, and gas form.
Layers of shells also are deposited in sediments on the ocean floor, forming carbonate rocks like limestone over long periods of time.
Carbon stores are also known as ____________ .
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9. Nutrient Cycles: The Carbon Cycle (continued)
Carbon is cycled through ____________ in a variety of ways.
____________ : energy from the sun allows CO2 and H2O to react
6CO2 + 6H2O + sunlight  C6H12O6 + 6O2
Carbon in the atmosphere is transformed by plants into carbohydrates.
Photosynthesis also occurs in cyanobacteria and algae in oceans.
____________ ____________ : carbohydrates release energy in consumers
C6H12O6 + O2  6CO2 + 6H2O + energy
The energy released is used for growth, repair, and other life processes.
____________ : decomposers break down large quantities of cellulose
Cellulose is a carbohydrate most other organisms cannot break down.
____________ processes: CO2 dissolves in cold, northern waters and sinks
Ocean currents flow to the tropics where the water rises and releases CO2.
This process is called ocean mixing.
____________ and fires – volcanic eruptions can release CO2.
Forest fires also release CO2.
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10. Nutrient Cycles: The Carbon Cycle (continued)
See page 76
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11. Nutrient Cycles: The Carbon Cycle (continued)
Many human activities can influence the carbon cycle.
Since the start of the Industrial ____________ (160 years ago), CO2 levels have increased by 30 percent due to the increased burning of fossil fuels.
The increase in CO2 levels in the previous years was percent
Carbon is being removed from long-term storage more quickly than it naturally would as we mine coal and drill for oil and gas.
CO2 is also a greenhouse gas, which absorbs heat in the atmosphere.
____________ ____________ for agriculture and urban development reduces plants that can absorb and convert CO2.
Farmed land does not remove as much CO2 as natural vegetation does.
Clearing Land for
Agriculture
Urban
Expansion
See page 77
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12. Nutrient Cycles: The Nitrogen Cycle
____________ is very important in the structure of DNA and proteins.
In animals, proteins are vital for muscle function.
In plants, nitrogen is important for growth.
The largest store of nitrogen is in the ____________ in the
form N2.
Approximately 78 percent of Earth’s atmosphere is N2 gas.
Nitrogen is also stored in oceans, and as organic matter in soil.
Smaller nitrogen stores are found in terrestrial ecosystems and
waterways.
Nitrogen is cycled through processes involving ____________ .
Nitrogen fixation
Nitrification
Uptake
See page 78
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13. Nutrient Cycles: The Nitrogen Cycle (continued)
Nitrogen fixation is the conversion of N2 gas into compounds containing ____________ (NO3–) and ____________ (NH4+).
Both nitrate and ammonium compounds are usable by ____________ .
Nitrogen fixation occurs in one of three ways.
In the ____________ – lightning provides the energy for N2 gas to react with O2 gas to form nitrate and ammonium ions.
Compounds formed by these ions then enter the soil via precipitation.
This provides only a small amount of nitrogen fixation.
In the ____________ – nitrogen-fixing bacteria like Rhizobium convert N2 gas into ammonium ions
These bacteria grow on the root nodules of legumes like peas.
The plants provide sugars, while bacteria provide nitrogen ions.
In the ____________ – some cyanobacteria convert N2 into ammonium during the process of photosynthesis.
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14. Nutrient Cycles: The Nitrogen Cycle (continued)
____________ occurs when certain soil bacteria convert ammonium.
Ammonium is converted into nitrates (NO3–) by nitrifying bacteria.
Ammonium is converted to nitrite (NO2–), which is then converted to nitrate.
____________ enter plant roots through the process of uptake.
These nitrogen compounds compose plant proteins.
Herbivores then eat plants and use nitrogen for DNA and protein synthesis.
Nitrogen is returned to the
atmosphere via ____________ .
Nitrates are converted back to N2
by denitrifying bacteria.
N2 is also returned to the
atmosphere through volcanic eruptions.
Nitrification
See page 80
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15. Nutrient Cycles: The Nitrogen Cycle (continued)
Excess nitrogen ____________ in water, enters the waterways, and washes into lakes and oceans.
The nitrogen compounds eventually become trapped in sedimentary rocks and will not be released again until the rocks undergo hundreds of years of weathering.
See page 81
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16. Nutrient Cycles: The Nitrogen Cycle (continued)
Human activities can also affect the nitrogen cycle.
Due to human activities, the amount of nitrogen
in the ecosystem has ____________ in the last 50 years.
Burning fossil fuels and treating sewage releases
nitrogen oxide (NO) and nitrogen dioxide (NO2).
Burning also releases nitrogen compounds that increase acid precipitation in the form of nitric acid (HNO3).
Agricultural practices often use large amounts of nitrogen-containing ____________ .
Excess nitrogen is washed away, or leaches, into the waterways.
This promotes huge growth in aquatic algae called algae blooms.
Algae blooms use up all CO2 and O2
and block sunlight, killing many aquatic organisms.
Algae blooms can also produce neurotoxins that poison animals.
Acid rain damaged these trees
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17. Nutrient Cycles: The Phosphorous Cycle
____________ is essential for life processes in plants and animals.
Phosphorus is a part of the molecule that carries energy in living cells.
Phosphorus promotes root growth, stem strength, and seed production.
In animals, phosphorous and calcium are important for strong bones.
Phosphorus is not ____________ in the atmosphere.
Instead, it is trapped in phosphates (PO43–, HPO42–, H2PO4–) found in rocks and in the sediments on the ocean floor.
____________ releases these phosphates from rocks.
Chemical weathering, via acid precipitation or lichens, releases phosphates.
Physical weathering, including wind, water and freezing, releases phosphates.
Phosphates are then absorbed by plants, which are then eaten by animals.
Weathering does not occur until there is geologic uplift,
exposing the rock to chemical and physical weathering.
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18. Nutrient Cycles: The Phosphorous Cycle (continued)
Humans add excess phosphorus to the environment through mining for ____________ components.
Extra phosphorus, often along with potassium, then enters the ecosystems faster than methods can replenish the natural stores.
Humans can also reduce phosphorus supplies.
Slash-and-burning of forests removes phosphorus from trees, and it then is deposited as ash in waterways.
The Phosphorus Cycle
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19. How Changes in Nutrient Cycles Affect Biodiversity
Any significant changes to any of these nutrients
(C, H, O, N, or P) can greatly affect ____________ .
Carbon cycle changes contribute to climate change and global ____________ .
Slight temperature fluctuations and changes in
water levels can drastically change ecosystems.
Changes influence other organism in the
food webs.
Increased levels of nitrogen can allow certain plant
species to ____________ other species, decreasing
resources for every species in the food webs.
Decreased levels of phosphorus can inhibit the
growth of algae that are very important
producers in many food chains.
Salmon are sensitive to temperature changes.
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Take the Section 2.2 Quiz
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20. 2.3 Effect of Bioaccumulation on Ecosystems
____________ live on both land and in the water.
Amphibians are sensitive to ____________ changes in the environment.
They are therefore valuable ____________ of environmental health.
Since the 1980s, many of the world’s amphibian species have suffered declines in population.
There also have been alarming increases in amphibian birth ____________ .
Many theories attempt to explain these changes, including drought, increased UV rays, pollution, habitat loss, parasites, and diseases.
Amphibians, like this frog, have exhibited drastic changes since the 1980s.
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21. Bioaccumulation
____________ refers to the gradual buildup of chemicals in living organisms.
Many harmful chemicals cannot be decomposed naturally.
These chemicals can be eaten or absorbed and sometimes
cannot be removed from the body of the organism effectively.
If a ____________ species suffers a chemical bioaccumulation,
it can affect every other organism in its far-reaching niches.
A keystone species is a ____________ part of an ecosystem.
Biomagnification is the process by which chemicals become more ____________ at each trophic level.
At each level of the food ____________ , chemicals that do not get broken down build up in organisms.
When a consumer in the next trophic level eats organisms with a chemical accumulation, it receives a ____________ dose of the chemical(s).
Organisms are sometimes exposed to toxic chemicals.
See page 94
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22. Bioaccumulation (continued)
An example of ____________ in British Columbia is the effect of PCBs on the Orca.
PCBs are chemicals that were used for many industrial and electrical applications in the mid-20th century.
PCBs were banned in 1977 because of their environmental impact.
PCBs bioaccumulate and
have a long half-life
(they break down very slowly).
PCBs will affect the
reproductive cycles of orcas
until at least 2030.
See page 95
The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae.
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23. Bioaccumulation (continued)
Chemicals like PCBs and DDT are called
____________ organic pollutants (POPs).
POPs contain carbon, like all organic compounds, and ____________ in water and soil for many years.
Many POPs are ____________ , used to control pest populations.
DDT was introduced in 1941 to control mosquito populations, and is still used in some places in the world.
Like PCBs, DDT also bioaccumulates
and has a long half-life.
Even at low levels (5 ppm), DDT in
animals can cause nervous, immune,
and reproductive system disorders.
ppm = parts per million
Spraying DDT, 1958
See page 96
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24. Bioaccumulation (continued)
____________ are metallic elements that are toxic to organisms.
Levels of lead in the soil have increased due to human activities.
Lead is not considered safe at any level.
Many electronics contain lead and must
be recycled carefully.
Lead can cause anemia and nervous and
reproductive system damage.
Cadmium is also found in low levels naturally.
Cadmium is used in the manufacture of plastics
and nickel-cadmium batteries.
It is toxic to earthworms and causes many health problems in fish.
In humans, the main source of cadmium is exposure to cigarette smoke.
Cadmium causes lung diseases, cancer,
and nervous and immune system damage.
Electronics Waste Contains Lead.
See page 97
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25. Bioaccumulation (continued)
____________ also is found naturally.
Mercury has entered ecosystems through the burning of fossil fuels, waste incineration, mining, and the manufacture of items like batteries.
Coal burning accounts for 40 percent of the mercury released into the atmosphere.
Mercury bioaccumulates in the brain, heart and kidneys of many animals.
Mercury compounds bioaccumulate in fish, adding risk for any organisms eating fish.
Reducing the effects of chemical pollution
____________ is the use of micro-organisms or plants to help clean up toxic chemicals.
Example: the oil industry uses bacteria to “eat” oil spills.
By trapping chemicals in the soil, they cannot enter the food chains as easily.
See pages
Take the Section 2.3 Quiz
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