Name:_____________________________     Date:___________________  

 

2.1 Energy Flow in Ecosystems Student Notes

General Information

Biomass is ___________________________________________________________ ______________________________________________________________________

• Biomass is also sometimes used to measure the mass of organic materials that are used to produce biofuels such as biogas.

• Biomass is generally measured in g/m2 or kg/m2

Within an organism’s niche, the organism interacts with the ecosystem by:

1._______________________________________________________________

2._______________________________________________________________

• Plants are called “producers” because they produce carbohydrates from carbon dioxide, water and the sun’s energy, a process called photosynthesis.

• “_____________________________” get their energy by feeding on producers or other consumers.

• ______________________________ is the break-down of wastes and dead organisms, by organisms called “decomposers”, through the process of biodegradation.

Energy Flow

Scientists use different methods to represent energy moving through ecosystems. • Food chains • Food webs • Food pyramids

Name:_____________________________     Date:___________________  

 

Food chains show the flow of energy in an ecosystem

• Each step is a __________________________ Feeding & niche relationship

• _______________________ = 1st trophic level • _______________________ = 2nd trophic

level • _______________________ = 3rd trophic level

• ____________________________________ =

4th trophic level

Energy Flow and Types of Consumers

Consumers in a food chain can be classified as: 1. __________________________ - consumers that obtain

energy and nutrients from dead organisms and waste matter and includes small insects, earthworms, bacteria and fungi Detrivores feed at___________________ trophic level

• Detrivores have their own, separate food chains, and are ___________________________

2. _________________________- primary consumers • herbivores eat plants (producers) only

3. _________________________ - secondary or tertiary consumers

• Secondary consumers eat non-producers, such as herbivores

• Tertiary consumers eat secondary consumers o Aka top consumers, top carnivores or top consumers

4. _________________________ - consumers that eat both plants and animals • Examples include humans and bears

Energy Flow - Food Webs

Most organisms are part of many food chains. A food web is used to represent _____________________________________________________.

Name:_____________________________     Date:___________________  

 

• Food webs are models of the feeding relationship in an ecosystem.

• Arrows in a food web represent the _______________________

_________________________ and nutrients.

• Following the arrows _______

_________________________

_________________________

This food web represents a terrestrial ecosystem that could be found in British Columbia

Energy Flow - Food Pyramids

Food pyramids show the ____________________________________________ from one trophic level to another in a food chain.

• Energy enters at the first tropic level (producers), where there is a_________________ amount of biomass, and therefore _____________________energy

• It takes large quantities of organisms in one tropic level to meet the energy needs of the next trophic level because:

o Each level loses large amounts of the energy it gathers through basic processes of living.

o __________________ of energy taken in by consumers (at each level) is used in chemical reactions in the body, and is lost as heat energy.

o There is _____________________ energy if left over for growth or increase in biomass.

Name:_____________________________     Date:___________________  

 

Food pyramids are also known as ecological pyramids.

• Ecological pyramids may show ___________________________________________ ________________________________.

• The amount of life an ecosystem can contain is _______________________________ _____________________________ of the ecological pyramid, where producers capture energy from the sun.

• Each level in the energy pyramid = a loss of ______________ of total energy available

o Lower trophic levels have much larger populations than upper levels. o This shows the importance of maintaining large, biodiverse populations at

the lowest levels of the food pyramid

Practice Assignments: Complete crossword, quiz and Check your understanding questions at the end of the online notes.

Name:_____________________________     Date:___________________  

 

2.2 – Nutrient Cycles in Ecosystems Student Notes

General Information

Nutrients are __________________________________________________________ _____________________________________________________________________.

• 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

___________________ the amount of nutrients flowing out.

Human activities can _______________________________ 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 elements required for life.

• ________________________________________________ cycle between living things and the atmosphere.

• Phosphorous cycles in from _______________________________.

The Carbon Cycle

Carbon 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 locations.

• _____________________________ is found in aquatic and terrestrial organisms, and in CO2 in the atmosphere and top layers of the ocean.

• _______________________________ is found in middle and lower ocean layers as dissolved CO2, and in coal, oil and gas deposits in land and ocean sediments.

o Sedimentation traps many long-term stores of carbon o Layers of soil and decomposing organic matter become buried on land and

under the oceans.

Name:_____________________________     Date:___________________  

 

o Slowly, under great pressure over many years, _______________ ________________________________ form.

o Layers of shells also are deposited in sediments on the ocean floor, forming _____________________ rocks like limestone over long periods of time.

Carbon stores are also known as carbon sinks

Carbon is cycled through ecosystems in a variety of ways.

• Photosynthesis: energy from the sun allows CO2 and H2O to react

• Carbon in the _____________________ is transformed by plants into carbohydrates.

• Photosynthesis also occurs in cyanobacteria and algae in oceans. • Cellular respiration: ______________________________________________ in

consumers. (opposite of photosynthesis)

• The energy _____________________ is used for growth, repair and other life processes. Decomposition: decomposers break down large quantities of cellulose

o Cellulose is a carbohydrate most other organisms _______________________________________________________

• Ocean Processes: CO2 dissolves in cold, northern waters and sinks • Ocean currents flow to the tropics, the water rises and releases CO2

o This process is called ocean mixing. • Eruptions and fires: volcanic eruptions can _________________________

o Forest fires also release CO2

Name:_____________________________     Date:___________________  

 

Many human activities can influence the carbon cycle

• Since the start of the Industrial Revolution (160 years ago), CO2 levels have _______________________________ from the increased burning of fossil fuels.

• The increase in CO2 levels in the previous 160 000 years was 1% - 3% • Carbon is being ___________________________________________ more quickly than it naturally would as we mine coal and drill for oil and gas. • CO2 is also a ___________________________, which traps heat in the atmosphere.

Nitrogen Cycle

Nitrogen is very important in the structure of ______________________________.

• In animals, proteins are vital for______________________ function.

• In plants, nitrogen is important for ________________________.

The largest store of nitrogen is in the atmosphere in the form N2.

Name:_____________________________     Date:___________________  

 

• Approximately ______________of the 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 plants

1. _______________________

2. _______________________

3. _______________________

______________________ - is the conversion of N2 gas into compounds containing nitrate (NO3

–) and ammonium (NH4+)

• Both nitrate and ammonium compounds are usable by plants. • Nitrogen fixation occurs in one of three ways

1. ______________________ - 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 only provides a small amount of nitrogen fixation.

2. ___________________- nitrogen-fixing bacteria like Rhizobium in the soil 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.

3. _____________________ - some species of cyanobacteria also convert N2 into ammonium during the process of photosynthesis.

___________________ - 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.

Name:_____________________________     Date:___________________  

 

______________________ - enter plant roots via 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.

Excess nitrogen __________________________, 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 weather.

Name:_____________________________     Date:___________________  

 

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).

o Burning also releases nitrogen compounds that increase ____________________________________ in the form of nitric acid (HNO3).

o Agricultural practices often use large amounts of _________________ _________________________________________.

o Excess nitrogen is washed away, or________________, into the waterways.

This promotes huge growth in aquatic algae = ___________________________________

These algal blooms use up all __________________________ ________________________________, killing many aquatic organisms.

The algal blooms can also produce neurotoxins that poison animals.

• Clearing land for agriculture and urban development __________________ plants that can absorb and convert CO2.

o Farmed land __________________________________ CO2 as natural vegetation does.

Phosphorous Cycle

Phosphorous is essential for life processes in plants and animals.

• Phosphorous is a part of the molecule that carries energy in living cells. • Phosphorous promotes root growth, stem strength and seed production. • In animals, phosphorous and calcium are important for strong bones.

Phosphorous is not stored in the atmosphere.

• Instead, it is trapped in phosphates (PO43–, HPO4

2–, H2PO4–) found in rocks and in

the sediments on the ocean floor.

Weathering releases phosphates from rocks.

• Chemical weathering, via acid precipitation or lichens, releases phosphates.

Name:_____________________________     Date:___________________  

 

• Physical weathering, where wind, water and freezing release the phosphates. o Phosphates are then absorbed by plants, which are then eaten by animals.

• Weathering doesn’t occur until there is geologic uplift, exposing the rock to chemical and physical weathering.

Humans add excess phosphorous to the environment through ________________

______________________ components.

• Extra phosphorous, often along with potassium, then enters the ecosystems faster than methods can replenish the natural stores.

Humans can also reduce phosphorous supplies.

• _________________________________ of forests removes phosphorous from trees, and it then is deposited as ash in waterways.

Name:_____________________________     Date:___________________  

 

Nutrient Cycles and Biodiversity

Any significant changes to any of these nutrients (_______________________) can greatly impact biodiversity.

• Carbon cycle changes are adding to climate change and global warming. o Slight temperature fluctuations and changes in water levels can drastically

change ecosystems. o Changes influence every other organism in those food webs.

• _______________ levels of nitrogen can allow certain plant species to out-compete other species, decreasing resources for every species in those food webs.

• ________________ levels of phosphorous can inhibit the growth of algal species which are very important producers in many food chains.

Review Assignments: Complete the crossword, 2.2 quiz and the 2.2 Check your Understanding questions at the end of the lesson. Required Assignment: Complete 2.2 Assignment B - Case Study of Nitrogen Loading pg 88-89 in your textbook and then upload it to the appropriate drop box.

2.3 Bioaccumulation Student Notes

Introduction Amphibians (like frogs) are valuable indicators of ___________________________.

• They are also ___________________ to chemicals changes in the environment.

• Since the 1980s, much of the world’s amphibian species have suffered declines in population.

• There has also been alarming increases in amphibian birth deformities in that time.

• 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.

Name:_____________________________     Date:___________________  

 

Bioaccumulation Bioaccumulation refers to an organism slowly _______________________________ the amount of chemicals in their bodies.

• Many harmful chemicals ______________________ be decomposed naturally. • These chemicals can be eaten or absorbed, and sometimes cannot be removed

from the body of the organism effectively. • If a keystone species suffers a chemical bioaccumulation, it can

_______________________________ organism in its far reaching niches. o A keystone species is a vital part of an ecosystem.

Biomagnification refers to the animals at the ________________________________ receiving huge doses of accumulated chemicals.

• At each level of the food pyramid, chemicals that do not get broken down ________________________________________________ in organisms.

• When the consumer in the next trophic level eats organisms with a chemical accumulation, they receive a huge dose of the chemical(s).

An example of bioaccumulation in BC is the effect of PCBs on the Orca. • ________________ are a chemical that were used for many industrial and

electrical applications in the mid 20th century. • PCBs were ________________ in 1977 because of fears of their environmental

impact. • PCBs bioaccumulate, and also have a long-half life

(______________________________________________________). • PCBs will affect the reproductive cycles of Orcas until at least 2030.

Name:_____________________________     Date:___________________  

 

The bioaccumulation of PCBs begins with the absorption of the chemicals by microscopic plants and algae. Chemicals like PCBs and DDT are called ____________________________ (POPs)

• POPs contain carbon, like all organic compounds, and remain in water and soil for many years.

• Many POPs are insecticides, used to control pest populations. o DDT was introduced in 1941 to control mosquito populations, and is still

used in some places in the world. o Like PCBs, DDT also bioaccumulates and has a long half life. o At even low levels (5 ppm), DDT in animals can cause

__________________________________________________________. ppm = parts per million

___________________________ also bioaccumulate.

• Lead, mercury and cadmium are the most polluting heavy metals. o Lead is found naturally at low levels, but levels have increased.

Lead is _______________________________________________. Many electronics contain lead, and must be recycled carefully. Lead can _______________________________________________

damage. o Cadmium is also found in low levels naturally.

Cadmium is used in the manufacturing 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 exposure is _____________

_____________________________________. Cadmium causes lung diseases, cancer, nervous and immune system

damage. o Mercury also is found naturally.

Much more has entered ecosystems through the burning of fossil fuels, waste incineration, mining and the manufacture of items like batteries.

Coal burning adds ______________of of the mercury released into the atmosphere.

Mercury bioaccumulates in ________________________________ of many animals.

Fish bioaccumulate mercury compounds, adding risk for any organisms eating fish.

Name:_____________________________     Date:___________________  

 

Reducing the effects of chemical pollution can be accomplished in several ways. • By trapping chemicals in the soil, they cannot enter the food chains as easily. • Bioremediation is also used, ___________________________________ are used

to help clean up, and are then removed from the ecosystem. o The oil industry will often use bacteria to “eat” oil spills. o Certain natural species are also excellent at bioremediation.