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BCLN SCIENCE 10 – Rev July 2014

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Unit 2 ~ Learning Guide Name:

INSTRUCTIONS

Complete the following practice questions as you work through the related lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions about anything that you don't understand BEFORE you write the unit test.

2.1 NOTES: ENERGY FLOW IN ECOSYSTEMS

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 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.


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• 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 including:

• Food chains • Food webs • Food pyramids

Food chains show the flow of energy in an ecosystem. Each step is a level which describes the feeding and niche relationship.

o = 1st trophic level

o = 2nd trophic level

o = 3rd trophic level

o = 4th trophic level

o = 5th trophic level

Types of Consumers

1. = consumers that obtain energy and nutrients from dead organisms and waste matter

includes small insects, , bacteria and

detrivores feed at trophic level detrivores have their own, separate food chains, and

are very numerous 2. = primary consumers herbivores eat (producers) only


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3. = secondary or tertiary consumers

secondary consumers eat , such as

tertiary consumers eat consumers o aka top consumers or top carnivores

4. and animals

Examples include humans and bear

Food Webs

= consumers that eat both plants

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

Food webs are models of the feeding relationship in an ecosystem. Arrows in a food web represent the Following the arrows

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

Food Pyramids

Food pyramids show the from one trophic level to another in a food chain. Energy enters at the tropic level (producers), where there is a large amount of biomass, and therefore much energy. It takes large quantities of organisms in one tropic level to meet the energy needs of the next trophic level.

o Each level 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.


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o There is very little energy for growth or increase in biomass.

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 populations than

upper levels. o This shows the importance of maintaining large,

populations at the lowest levels of the food pyramid


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2.1 PRACTICE: ENERGY FLOW IN ECOSYSTEMS

Please complete the online crossword puzzle, the 2.1 Quiz and the 2.1 Check Your Understanding.

1. such as plants perform to produce carbohydrates from carbon dioxide, water and solar energy. (2 marks)

2. producers. (1 mark)

get their energy by eating carbohydrates from

3. Compare and contrast a food chain, food web, and food pyramid. (4 marks)

4. Identify the producer/consumer level of each of the following organisms. (5 marks)

a. spider = b. sunflower = c. bumble bee = d. swallow = e. hawk =


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5. Compare and contrast herbivore, carnivore, omnivore and detrivore

including describing their contributions to ecosystems. (4 marks)

6. In a food chain or food web, the arrow indicates the direction that is flowing. (1 mark)

7. percent of the energy is used up to sustain life at any given trophic level. This means that each successive trophic level can only support much organisms than the trophic level before it, resulting in a shaped diagram, where the base is than the top, if we look at energy, population numbers or biomass. (4 marks)


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2.2 NOTES: NUTRIENT CYCLESIN ECOSYSTEMS

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, , urban expansion, mining, and 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

o carbon is also an essential part of chemical processes that sustain life.

Carbon can be stored in many different locations: o

is found in aquatic and terrestrial , and in CO2 in

o is found in middle and lower ocean layers as dissolved CO2, and in coal, oil and gas


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deposits in land and ocean sediments. Sedimentation traps 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

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

Carbon is cycled through ecosystems in a variety of ways ;

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

Carbon in the is transformed by plants into carboydrates.

Photosynthesis also occurs in cyanobacteria and algae in oceans.

2. Cellular respiration: (opposite of photosynthesis)

in consumers.

The energy repair and other life processes.

is used for growth,

3. : decomposers break down large

quantities of cellulose Cellulose is a carbohydrate most other organisms


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4. : CO2 dissolves in cold,

northern waters and sinks Ocean currents flow to the tropics, the water rises and releases

CO2

This process is called ocean mixing.

5. Eruptions and fires: volcanic eruptions can

6. also release CO2

The Carbon Cycle


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Many human activities can influence the carbon cycle o Since the start of the Industrial Revolution (160 years ago), CO2 levels

have from the increased burning of fossil fuels.

o The increase in CO2 levels in the previous 160 000 years was 1% - 3%

o Carbon is being more quickly than it naturally would as we mine coal and drill for oil and gas.

o CO2 is also a , which traps heat in the atmosphere.

o Clearing land for agriculture and urban development reduces plants that can absorb and convert CO2.

o Farmed land does not remove as much CO2. Nitrogen Cycle

Nitrogen is very important in the structure of

o In animals, proteins are vital for function. o In plants, nitrogen is important for .

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

o Approximately of the Earth’s atmosphere is N2 gas. o Nitrogen is also stored in , and as organic matter in

. o Smaller nitrogen stores are found in

and .

Nitrogen is cycled through processes involving plants: 1. 2. 3.

1. Nitrogen fixation is the conversion of N2 gas into compounds containing

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

i. - lightning


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provides the energy for N2 gas to react with O2 gas to

form nitrate and ammonium ions. o Compounds formed by these ions then enter the soil via o This only provides a small amount of nitrogen fixation

ii. - nitrogen-fixing bacteria like Rhizobium in the soil convert N2 gas into

ammonium ions o These bacteria grow on the root nodules of legumes

like peas. o The plants provide sugars, while bacteria provide

nitrogen ions. iii. - some species of

cyanobacteria also convert N2 into ammonium during the

process of photosynthesis.

2. bacteria convert ammonium.

- occurs when certain soil

Ammonium is converted into nitrates (NO3–) by nitrifying bacteria.

Ammonium is converted to nitrite (NO2–), which is then converted

to nitrate.

3. 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 o Nitrates are converted back to N2 by denitrifying bacteria.

o N2 is also returned to the atmosphere through volcanic eruptions.

Excess nitrogen , enters the waterways, and washes into lakes and oceans.

o The nitrogen compounds eventually become trapped in sedimentary rocks, and will not be released again until the rocks .


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The Nitrogen Cycle

Human activities can also affect the nitrogen cycle. o Due to human activities, the amount of nitrogen in the ecosystem has

in the last 50 years. o Burning fossil fuels and treating sewage releases nitrogen oxide (NO)

and nitrogen dioxide (NO2).

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

o Agricultural practices often use large amounts of

Excess nitrogen is washed away, or , into the waterways.

This promotes huge growth in aquatic algae = .


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These algal blooms use up all the and and block sunlight, killing many aquatic organisms.

The algal blooms can also produce that poison animals.

Phosphorous Cycle

Phosphorous is essential for life processes in plants and animals. o Phosphorous is a part of the molecule that carries

in living cells. o Phosphorous promotes root , stem

and seed production. o In animals, phosphorous and calcium are important for

.

Phosphorous is not stored in the atmosphere.

o 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. o

lichens, releases phosphates weathering, via acid precipitation or

o weathering, where wind, water and freezing release the phosphates.

o Phosphates are then absorbed by plants, which are then eaten by animals.

o 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

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

Humans can also reduce phosphorous supplies. o

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


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The Phosphorus Cycle

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

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.


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2.2 PRACTICE: NUTRIENT CYCLES IN ECOSYSTEMS

2. Complete the online word search puzzle, the 2.2 Quiz and the 2.2 Check Your Understanding.

1. Chemicals that are required for growth and other life processes are called

. (1 mark)

2. The movement of nutrients throughout the biosphere is called

. (1 mark)

3. Nutrients accumulate in nutrient mark)

4. Five key elements required for life are (5 marks):

or sinks. (1

a. b. c. d. e.

5. Use the Nutrient Cycle diagrams provided in the learning guide to answer the following questions. Be sure to include units where appropriate. (12 marks)

a. What is the greatest carbon store and how much carbon does it

store?

b. How much carbon is added to the atmosphere due to fossil fuel combustion?

c. What is the major process that removes carbon from the atmosphere?

d. Approximately how long does it take to move carbon into long term stores such as oil and gas?


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e. How does nitrification occur in the soil?

f. How is nitrogen removed from the soil and returned to the atmosphere?

g. Why is it dangerous to have nitrogen oxides (NO and NO2) in the atmosphere?

h. What is the greatest phosphorous store and how much phosphorus does it store?

i. How is phosphorous released from rocks?

j. How are human activities altering the balance of the phosphorous cycle?

6. Define and explain the process of eutrophication. (2 marks)


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7. Complete the following table that compares the Carbon, Nitrogen and

Phosphorous cycles.

Carbon

Phosphorus

Nitrogen

Interactions

with Humans

- Humans

produce by burning fossil fuels.

- Humans add to environment by applying fertilizer in agriculture.

- Humans add to atmosphere by transportation and industry.

Interactions with Plants

Nutrient

present in the

Atmosphere

Yes or No

Nutrient

present in the Ocean

Yes or No

Nutrient

present in the Rocks

Yes or No


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8. Adapted from BC SCIENCE 10, pp. 88-89. A Case Study of Nitrogen Loading.

British Columbia's lower Fraser Valley is an important agricultural region that produces meat, dairy products, berries, vegetables, fruit, and mushrooms. The area is unique because it has a high rate of agricultural production even though its farms are almost 10 percent the size of typical farms in the province. However, run-off from agricultural and lawn fertilizers and leeching from septic systems are placing excess nitrogen into the environment. This is called nitrogen loading. In this activity, you will investigate the sources of nitrogen and the trends in nitrogen loading in a Fraser Valley study area. You will then make recommendations to reduce nitrogen loading in this area.

Question: How can the excess levels of nitrogen be reduced in the Fraser valley?

Procedure:

1. Table A shows the number of kilograms of nutrient required by corn and grass crops for

each hectare planted each year. Table B shows the number of kilograms of nutrients from manure and chemical fertilizers applied to each hectare of these crops each year. Please study the tables and answer the following questions.

Table A. Nutrients Required By Corn and Grass Crops

Crop

Amount of Nutrient Required per Hectare

Nitrogen (kg)

Phosphorous (kg)

Potassium (kg)

Corn

140 40

79

Grass

230 22

50

Table B. Nutrients Applied to Corn and Grass Crops in the Fraser Valley

Crop

Amount of Nutrient Applied per Hectare

Nitrogen (kg) Phosphorous (kg)

Potassium (kg)

Fertilizer

68 17

34

Manure

205 67

131

Total

273 84

165


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a. Which crop requires less nitrogen per year?

b. In a 1 hectare (ha) cornfield that has had nutrients applied, how many kilograms of nitrogen, phosphorous, and potassium will not be assimilated (not be taken up) by the crop? (show calculations for marks)

2. Using Tables C and D and the grid provided below, construct a bar graph to show the trend in the amount of crops grown and excess nitrogen in the Fraser Valley study area.

Table C. Trends in the Amount of Crops Grown

Year Grass (ha)

Corn/Grain (ha)

Small Fruit (ha)

1971

2418 290 588

1981

1455 136 1259

1991

1038 25 1651

Table D. Estimated Excess Nitrogen in the Study Area

Year

Nitrogen (kg/ha)

1971 134

1981 185

1991 245


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Graph Requirements:

graph has an informative title years are on x-axis (x is "a cross" and goes across the page,

horizontal) amount of crops is on left hand y-axis (y "in the sky", vertical)

represented with a bar graph having 3 bars for each year. excess nitrogen is on right hand y-axis represented by a line graph a bar graph neatly drawn with a ruler a legend is provided all axis must have informative titles and appropriate units in

brackets each division on an axis must represent the same value (example:

10 years=5 spaces, 5 ha=1 space – these are only exampes) Though it is better to do both graphs on one sheet if needed you

may create two graphs to convey this information.


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3. Looking at your bar graph, what relationships do you see between crops grown and excess nitrogen in the study area?

4. Analyze Table E at the bottom of this page to answer the following questions:

a. What changes have occurred from 1971 to 1991 in the number of livestock

raised in the study area?

b. How might these changes affect the level of excess nitrogen?

c. Concentrated animal protein is used to feed chickens on poultry farms to make them grow quickly. How might this type of food add to excess nitrogen?

d. The human population in the area is also growing rapidly. How could rapid population growth lead to excess nitrogen?

Table E. Trends in the Number of Livestock Raised in the Fraser Valley.

Year

Pigs Dairy/Beef Chickens

1971

444 5049 212 200

1981

9508 4276 Not available

1991

1038 2199 1 346 600


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Analyze:

1. Describe how the Nitrogen Cycle diagram from your notes would change for the Fraser

Valley given the information gained on the previous pages of this assignment. Focus on the influence that human activities might have on the cycle. Use the word balance in your description.

2. A famer in the Fraser Valley is concerned about nutrient overloading in the area. Outline an experiment that could be used to determine how much nitrogen the farmer will need to grow healthy raspberry plants without producing a nitrogen overload. Nitrogen overload can be measured by analyzing the Nitrogen content of water released from a plant or plots of plants after watering. Remember that a good experiment always has a control.


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Conclude and Apply:

1. You are part of an assessment team asked to make recommendations to the government of

British Columbia and to farmers in the region on how the area can provide food to the province and protect the environment. Analyze the data above and create a list of recommendations. Consider types of foods to grow, amount of fertilizer, type of fertilizer, protective measures for the environment and any other information you can think of.

2. Is it possible for humans to avoid disrupting nutrient cycles? Explain your answer.


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2.3 NOTES: BIOACCUMULATION

Introduction

Amphibians (like frogs) are valuable indicators of

They are also environment.

to chemical changes in the

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 the frog to the right, have exhibited drastic changes since the 1980s

Bioaccumulation

Bioaccumulation refers to an organism slowly the amount of toxic chemicals in their body.

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 every other organism in its far reaching niches

o A 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 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. o are a chemical that were used for many industrial

and electrical applications in the mid-20th century.


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o PCBs were

their environmental impact. in 1977 because of fears of

o PCBs bioaccumulate and also have a long-half life ( _)

o PCBs will affect the reproductive cycles of Orcas until at least 2030.

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

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

o 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. o

polluting heavy metals. are the most

o Lead is found naturally at low levels, but levels have increased.


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

o Cadmium is also found in low levels naturally Cadmium is used in the manufacturing of

and 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, , nervous and system damage.

o Mercury also is found naturally. Much more has entered ecosystems through the burning of

, waste incineration, and the manufacture of items like batteries.

Coal burning adds released into the atmosphere.

Mercury bioaccumulates in the of many animals.

Fish bioaccumulate mercury compounds, adding risk for any organisms .

Reducing the effects of chemical pollution can be accomplished in several ways. o By trapping chemicals in the soil, they cannot enter the food chains as

easily. o is also used,

are used to help clean up, and are then removed from the ecosystem.

The oil industry will often use to “eat” oil spills.

Certain natural species are also excellent at bioremediation.


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2.3 PRACTICE: BIOACCUMULATION

1. Complete the online word search puzzle, the 2.3 Quiz and the 2.3 Check Your Understanding.

2. Compare and contrast the bioaccumulation and biomagnification. (3 marks)

3. Which trophic level experiences the greatest amount of biomagnification? (1 mark)

4. What does it mean when a chemical is said to have a long half-life? (1 mark)

5. Define POPs and explain what each word in POP actually means with respect to these types of chemicals. (4 marks)


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6. Bioremediation is an important approach to reversing damages done to

the environment by human activities:

a. Define bioremediation (1 mark)

b. Use the internet to research and describe one example of bioremediation that is not mentioned in the online notes. (2 marks)

7. Complete the Unit 2 Review by following the link on the right-hand side bar menu.


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Unit 2 Learning Guide Answers

2.1 1) Producers, photosynthesis, 2) Consumers, 3) See definitions for Food web, chain and Pyramid and then relate them, 4) Consumer, producer, consumer, consumer, consumer, 5) See definitions for herbivore, omnivore and carnivore. Each consume energy from the previous trophic level. Each is part of a food web and each provides material that decays back into the environment. 6) Energy, 7) 90, fewer, pyramid, much larger.

2.2 1) nutrients, 2) nutrient cycling, 3) stores 4) carbon, phosphorus, nitrogen, oxygen, hydrogen, 5) a.Marine sediments - 68-100 million gigatonnes, b. 5.5 gigatonnes, c. photosynthesis, d. millions of years, e. bacteria convert ammonium to nitrates, f. denitrification and vocanos, g. can cause acid rain, h. Earth’s crust, 20 million gigatonnes, i. mining, j. more Phosphorus is released than is reabsorbed. 6) see notes page 7. Plants use carbon to make glucose with the energy from the sun, Plants uptake Phosphorus for growth, Plants uptake Nitrogen for growth, all nutrients present in all areas except Phosphorus is not found in the atmosphere, 8) 1. a. Corn, b. excess N – 133kg, excess P - 44 kg, excess Potassium 86kg, 2. Graph should show 3 bars for each year representing each type of crop and a line graph that increases indicating the excess nitrogen, 3. Excess nitrogen increase as fruit trees increase, 4. a. livestock numbers have increased, b. nitrogen should increase, c. protein is high in nitrogen therefore increases will excess nitrogen levels, d. sewage has high nitrogen and therefore will increases excess nitrogen levels. Remaining questions: answers will vary.

2.3 2) see definitions on page 25, 3) Top level, 4) It lasts for a long time in the environment before degrading, 5) Persistent organic pollutants, see notes answer will vary, 6) a. see notes page 27, b. answers will vary

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