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Science 1206 - Life Science 1

Diversity in Ecosystems - Unit 1

Paradigms and Paradigm Shifts

Paradigm - a belief held by society, based on general beliefs, such as morals, values andevidence.

Paradigm shift - rare and significant changes in the way humans view the world. They aremajor changes which are very controversial when first proposed but whicheventually become accepted as major advances in scientific knowledgeand understanding.

Discuss paradigms with students. Give everyday examples. Have them suggestexamples. Discuss with them their own paradigms related to their use of the naturalenvironment. What do they value about nature?

Eg. Sport fishing, hunting, camping, ATVing, snowmobiling, natural beauty, peace andquiet of the forest, etc.

Discuss with them our past paradigms about how we use nature for our own means. Discuss our pollution of the world, ozone destruction, global warming, raping of the world’sforests and fisheries.

Discuss how our paradigms about natural resources must and are changing and how they,as students today, are becoming a part of a paradigm shift, as they are taught about the 4 R’s(recycle, reuse, recover, etc.) and sustainability concepts.

Sustainability - the wise use of our renewable resources today so that both the resourcesand the environment will be there for use by future generations

Sustainability is in itself a paradigm and has been part of a paradigm shift. People todayconsider the use of resources differently that they did in the past. You as students today are beinggiven the concepts to understand that we must practice sustainability of our resources - it’s theright thing to do!!!

.

) Differences in abiotic factors on our earth affect the diversity of living things on ourplanet.

abiotic factor- any nonliving factor in an ecosystem such as ppt., sunlight,temperature, wind, etc.


) Biodiversity - refers to the number of species of organisms found in an area.

) Animals depend on plants to survive. Why? ( plants are producers - they can use solarenergy by using a process called photosynthesis to make their own food.)

) Do p. 9. Q. 1 (a) and (b),

T Discuss Q. 2, p. 9 with class or assign to portfolio

T Do: Discussion - “Take a Stand, P. 21. The plight of the wolves inYellowstone National Park - go over background info. in text. Assign discussion groups. 20 min activity discussion. ( Studentscould place this in their portfolios.)

T Assign “work the web activities” - these serve as examples of ourchanging paradigms towards the environment.

The Biotic Factors:

Biodiversity - the number of organism species found in an area. The tropical rain forestshave the highest biodiversities. The polar ice caps have the lowestbiodiversities.

) Ecosystem - is a term used to describe the relationships between organisms and theabiotic factors in their environment.

) Ecology - the branch of science which studies the interrelationships betweenorganisms (biotic factors) and abiotic factors in ecosystems.

) Food chain - is a step by step sequence linking organisms that feed on each other. Itshows how energy is transferred between organisms. ( se fig. 2. p. 11)

) Food web - a diagram that tries to show the energy transfer relationship between manyorganisms in an ecosystem.

) biotic factors - a factor in an ecosystem created by the presence and roles of otherliving things. ( e.g. producers, consumers, disease, competition forfood, symbiosis, predator / prey relationships, etc.)

) abiotic factor - nonliving factors in the environment which influence biotic(living)organisms. e.g. ppt., temp., wind speed, shade, soil type, etc.


The various types of living biotic factors are:

- there are two major groups of living organisms - producers and consumers

A. Producers - are organisms that make their own food through photosynthesis orchemosynthesis. (e.g. green plants, bacteria that use sulfur for food.)

B Consumers - are any organism which must eat (consume) other organisms for food. (e.g. rabbit eats plants, fox eats a rabbit)

The categories (types) of consumer types are:

1. Herbivores- consumers that eat only plants. e.g. rabbits, grasshopper, moose,caribou, cow.

2. Carnivores - consumers that eat other consumers. e.g. fox, wolf, owl, hawk,lion, tiger.

3. Omnivores- consumers that eat both plants and animals. e.g. humans, bears,racoons.

4. Saprophytes (also called decomposers) - organisms that break down detritus to get nutrients for their own use but in doing so also releasevaluable nutrients back into the soil or water that can be used byproducers. They convert organic material into inorganic material.

detritus - wastes from plants and animals, including their dead remains.

5. Scavengers - feed on dead organisms. They do not do the same job assaprophytes.

- Biotic factors also include any process, relationship or material that results from livingorganisms.

Some examples of biotic factors which are not living organisms are:

6. Competition - organisms species compete with each other and other species forresources such as food, space, mates. There are two types of competition: (a)interspecific competition - when organisms of different species compete for thesame resource e.g. wolves and foxes both competing for the same types of food and (b) intraspecific competition - when organisms of the same species competefor the same resource e.g. two male mountain sheep competing for the same food


or same mate.

7. Predator / prey relationship - predators capture and eat prey animals. e.g. Lynxeating snowshoe hares.

For over 300 years, the Hudson Bay Company has been involved in the furtrade in Canada. Company records show that the number of snowshoe hare peltsbought tends to fluctuate in a ten-year cycle, as does the number of lynx.However, the changes in the lynx cycle tend to lag behind those of the hare byabout a year. This is a cyclic relationship. When the hare population is at itshighest, the lynx population is usually at a low level. This is because food is themain limiting factor on prey populations, not the predators. When a herbivorepopulation becomes too high, they use up their food supply, damaging theirhabitat. As a result, their numbers then decrease as many starve and die. Asfewer prey animals are available, the lynx population starts to decline as well. Eventually, the hare population starts to increase again as more plants grow back. The lynx population also starts to rebuild but its reproductive rate is much slowerthan the hares so the Lynx population experiences a “lag” period. By the timethey have increased, the hares have already over- populated again and are indecline again. Observe this graph showing the population growth patterns ofLynx and hares over time:


8. Disease - limits population growth. The higher numbers a population has, thefaster disease spreads. Disease spreads faster in higher population densities.

9. Decomposing organisms - must be recycled by saprophytes.

10. Symbiosis - a close biological relationship shared between two organisms. There are three types :

a. mutualism - where two organism benefit each other; in many casesneither can survive without the other. e.g. lichens - madeup of algae and fungi in the one body. This allows lichensto live on bare rock. The fungi provide shelter andmoisture for the algae. The fungus can corrode and breakdown rock to get minerals. The fungi passes the mineralsto the algae and provide it with water so the algae can makefood by photosynthesis. Any extra food that the algae doesnot need, it passes to the fungi. Another example is theclown fish and the sea anemone. The sea anemone is anattached animal. It has tentacles with poisonous stingers tocatch its prey, which are fish. The clown fish can liveamongst the tentacles of the sea anemone. They are notaffected. The clown fish is protected by the anemone. Inreturn, the clown fish act as live “lures”, attracting predatorfish to the sea anemone, where they are captured and eaten.

b. commensalism - where one organism, called the commensal, benefits andthe host organism does not. The host is not harmed. Anexample would be the Remora fish and sharks. TheRemora is a poor swimmer but it has a sucker on its head. It attaches itself to the sides of sharks to hitch a free ride. When the sharks feed, the remora fish then feed on scrapsof food left in the water from the shark’s feeding. Theremora ( the commensal ) benefits and the host, the shark,is not affected.

c. parasitism - where a parasitic organism, called a parasite, benefits from livingon or in a host organism but harms the host organism. e.g.tapeworms in a human - the tapeworm gets a place to live,protection, and food from our digestive system. At the same timethey make us sick by stealing our nutrition. e.g. trichonosis -parasitic worms that get into our muscle tissue and form cystsaround themselves so that our immune system cannot destroythem. They cause us pain and make us weak by robbing our


muscles of oxygen and nutrition.

Abiotic Factors (nonliving and not from or caused by living things)

Some of theses are:

1. Space - refers to the amount of room an organism needs to survive. Thisvaries with the organism. Some organisms are very territorial andmark out and defend their hunting area from others. eg. NL pinemarten needs 7 - 9 km of undisturbed old growth forest to survive.2

2. temperature - many organisms are adapted to a certain temperature range. Average temperatures vary with latitude and altitude. Thefurther North or South of the tropics you go, temp.decreases. As temp. decreases, so does the biodiversity. This also happens as you go up a mountainside. As tempdecreases, so does biodiversity. The decrease in temp withlatitude and altitude is called latitudinal/altitudinalsuccession.

e.g. few species live at the poles but most species live in the tropical zones

3. oxygen - concentration can vary with altitude. The higher up a mountainsideyou go, the less oxygen there is. Varies in water; dissolved oxygenconc. affects aquatic life present.

4. light - amount received varies with latitude. Tropical zones receive more directsunlight than the polar regions. More sunlight means warmertemperatures, more plants and animals, (more biodiversity) Light alsovaries with depth in water environments. Beyond 200m down, no lightpenetrates, so no producers live there, just consumers.

` 5. water - ppt. varies with latitude and proximity to large water bodies. Areas receiving little ppt. have least biodiversity. The tropicalzones get the most. Ppt decreases as you go towards the poles. This results in less biodiversity.

6. soil nutrients - humus content, mineral content , pH of soil all affect thedistribution of plants, which in turn affect the distributionof animals.

T DO - # 1, 2, 3 - p. 13


� Do - Work the web - the Northern Cricket p. 13 .

T DO- Understanding Concepts, p. 15. # 2., 4

� DO- Work the web, p. 15 , Peregrine falcon.

T DO - assign understanding the concepts # 1. (a), (c), 2, 3, 4(a)

T Do # 5, p. 33 - Mini - Case study on Abiotic factors

� DO -, Work the web, p. 19 Whooping Crane

Ecological Succession - an example of how abiotic and biotic factors interactin an environment.

) Ecology is a branch of science that studies the interactions between plants and animal. Organisms live in populations.population - all of the members of the same species living in the same habitat

) The many populations in a habitat make up the biological community. ( ref - pp. 22-23)

) community - the many populations in a habitat

) when studying community, an ecologist studies how biotic factors affect each population. They also study the effect of abiotic factors on populations. Ecological succession is anexcellent example of the interaction between abiotic and biotic factors.

) Ecological succession - a natural process whereby the interaction between abioticand biotic factors in an environment cause a series ofchanges to occur in the species of organisms living there,leading to a stable, climax community.

) climax community - the final, stable stage in any ecological succession.

) an example of ecological succession would be the process whereby bare rock managed to,over considerable time, change into forest or a pond fills in to become a bogland or aforested area.


) several factors contribute to ecological succession. Some of the main ones are soilcomposition, soil depth, decomposition of dead organisms, available light andcompetition.

Stages of Bare Rock to Forest Succession:

) The stages of primary ecological succession, also called bare rock to forest ecologicalsuccession are:

1. lichen stage -lichens are an organism made up from a mutualism relationship between an algae and a fungi. The lichen corrodes the rock by secreting acids. This allowsthe lichen to get minerals it needs to grow. The algae part of the lichen uses theminerals and water to carry out photosynthesis to make food. Over time, lichenslive, die and decay. This creates a weak, thin soil in pockets on the rock, onwhich new lichens grow. As the soil thickens and becomes richer over time,abiotic factors in the soil change, allowing it to support more complex plants.

2. Moss stage -mosses move in , take root and eventually out compete the lichens for the space. The mosses take over and over time, their decay changes the soil. It becomesdeeper and richer in abiotic nutrients. This allows grasses to invade.

3. Grass stage - grasses out compete the mosses for most of the space. Over time, the soil gets further enriched when grasses live, die and decompose. This thickens and makes thesoil richer in abiotic components.

4. shrub stage - When the soil is rich and deep enough, shrubs out compete the grasses, blocking out their light and taking over the area.

5. Tree/forest stage - the soil finally becomes deep enough and rich enough to allow trees to grow. They out compete many shrubs by blocking their light. Only shrubs and otherplants which can tolerate low light remain under the trees.

The stage in an ecological succession is called the:

“Climax community” - the final, stable community which will stay that way if leftundisturbed.

Ecological Niches - pp. 40 - 41

) ecological niche - an organism’s place in the food web, its habitat, its breeding area,etc. It includes everything that it does to survive and reproduce.

) each species in an ecosystem tends to have a different niche. e.g. owls and hawks mayfeed on many of the same animals but owls hunt mainly in the forests while hawks huntmainly in open fields. Owls hunt mainly at night, hawks in the day. Owls and hawks


even nest in different areas. Their different adaptations help them occupy their differentniches. These prevents them from being in complete competition with each other.(mention different species of warblers and how they reduce competition, p. 41)

) When a new species enters an area, it is called an exotic species.

) exotic species - a new species introduced to an ecosystem either naturally or by humans,either on purpose or accidentally.

) many times exotic species will cause a disturbance because it will most likely begin tocompete for a niche with one or more species that are already there.

T Do - # 3, p. 44 - Students make pro and con chart of the introduction ofthe Zebra Mussel to the Great Lakes. or do research on some othertype of exotic species such as Russian thistle, starlings, eelgrass, etc.

Comparing Ecosystems a Case Study - pp28 - 29.

T DO - case study items (a) - (m) and also #1. (a) and 2. (a).

Relative humidity - is a measure of the % of water vapor in an air mass compared withthe maximum amount of water vapor that can be held at thattemperature.

Evaporation rate - measures the volume of water lost from soil in one day.

Trophic Levels in Ecosystems - Food chains and Food Webs pp. - 34 - 39.

Food chain - a line diagram showing “what eats what”. Arrows are used to indicate thedirection in which energy\food is flowing. A food chain always starts with an autotroph.

Algae ----------> tadpole ------------> trout -----------------> otter(Producer) (Herbivore) (Carnivore) (Carnivore)1 trophic level 2 trophic level 3 trophic level 4 trophic levelst nd rd th

primary consumer secondary consumer

As shown in the example above the otter is at the 4 trophic level The trout is at the 3th rd

trophic level. Most predators are at higher trophic levels such as second or third order.

Trophic level - a position in a food or energy chain. It is determined by the


number of feeding levels beneath it.

Food Web - (more complex than a food chain.) It is a model which attempts to showall the interrelated feeding relationships in an ecosystem (see eg. p. 35)

autotroph - a producer, a green plant, which can trap solar energy and make their ownfood to provide a base for all life on earth.

Primary consumer - are herbivores. They feed directly on autotrophs.

Secondary consumer - are animals in the third trophic level that feed onherbivores.

Tertiary consumer - a carnivore that has eaten another carnivore.

Top carnivore - the last carnivore in any food chain. No other animal eatsit.

The Effect of Greater Biodiversity on Ecosystem Stability:

T .

/ Look at food chain, p. 11. Also see p. 43. What would happen to the frog population ifthe grasshopper population were lowered by the use of pesticides? ( discussed in class).

Food Webs, Niches and Competition:

T Do assigned food web examples: Students will complete food web assignment 1

Change and Stability in Ecosystems - pp. 48 - 49

Ecosystems appear to be stable. The many interrelated food chains give a communitystability. They undergo continuous renewal to remain that way. They remain in equilibrium - astate of balance. Large changes in abiotic or biotic factors, such as those caused by humans, cancause a shift in this balance. Ecosystems can often recover, even after a lot of humaninterference, but it can take many years, even hundreds of years. Recovery depends on thebiodiversity of the ecosystem. The greater the biodiversity in an ecosystem’s foodweb, the morestable it is. It is not as easily affected if some populations become lower or even disappear. In


the arctic, where biodiversity is low, foodwebs are easily affected by small changes in any onepopulation

Energy Flow in Ecosystems - ( read pp. 32- 39).

T the source of all energy for ecosystems is the sun. It provides energy for producers tomake food by photosynthesis. It drives the water cycle and determines weather.

T Photosynthesis - the process by which green plants use sunlight, water and oxygento produce carbohydrates (sugars ).

T only a tiny % of the sunlight reaching the earth gets used by plants, only about 0023 %. Much of the light entering the earth’s atmosphere gets reflected away by objects such asclouds.

T Albedo - a measurement of the % of light that an object reflects.

T the amount of energy available in a food web decreases with each higher feeding level. Each higher feeding level population only receives 10% of the energy present in the lowertrophic.

Algae -------> tadpole ------------> trout -----------------> otterGets 10% of energy gets 10% of energy gets 10% of energy Algae had tadpole had trout had

We can represent this in calories. Lets say the algae population has stored in it 1000calories per 1000 m . What portion of this energy would be received in the higher trophic levels2

of this food chain?

Algae -------> tadpole ------------> trout -----------------> otter

1000 cal/m . 100 cal/m . 10 cal/m . 1 cal/m . 3 3 3 3

(10% of 1000) (10% of 100) (10% of 10)

With the otter being a tertiary consumer in this food chain, it is only receiving 0.001% ofthe original calories in the algae population.

T Each trophic level only receives 10% of the energy in the previous trophic level. Thishappens because only a small fraction of the energy/food taken in becomes stored as newtissue in the consumer.


T Some reasons why energy is lost between trophic levels are:

1. Much of the food eaten is cannot be fully digested and absorbed so it passes out in thefeces.

2. Not all of the food gets eaten e.g. bones, ligament, etc.3. A large portion of the energy a consumer takes in is used for body processes such as cell

repair. Much of this energy gets lost as heat from their bodies.4. Not all plants or animals are eaten by other consumers. This energy is never passed on.

T Discussion: extra examples on pp. 36 - 39. . e.g. deer and fox energytransfers/lost energy

T Because of this loss of energy between trophic levels, a pyramid model is used byscientists to illustrate it. The greatest amount of energy is found in the producers, thebase of the pyramid and the least amount is found at the top, the tertiary consumers.

The Pyramid Models:

T Since the amount of energy received by population of organisms decreases at each trophiclevel, then the total mass of living organisms that can be supported at each level decreasestoo. This is relationship can also be shown by a pyramid model, called the pyramid ofbiomass.

T biomass - the total dry mass of living organisms in a habitat. (calculated)


) Lastly, because of the less energy and biomass available at the higher trophic levels, thereare fewer animals in these levels. Generally speaking, there are always more herbivoresthan carnivores in an ecosystem, because carnivores are at a higher trophic level and theirpopulations receive less energy. This can also be represented by a pyramid of numbersmodel.

Energy flowing from the sun through ecosystems must follow the two Laws ofThermodynamics. (p. 36) It is for this reason that energy is lost between trophic levels:

1. 1 Law of thermodynamics - energy cannot be created or destroyed, butst

can change its form2. 2 Law of thermodynamics - during any transformation of energy, somend

of the energy is changed into an unusableform, such as heat, and is lost from thesystem.


) assign questions p. 39, #1- 10. and p. 33, #1p. 46, # 7,8

Pesticide Use; it history (read pp. 52 - 53, 55)

Pesticide - chemicals designed to kill pests.

Pest - an organism which humans have decided is harmful or inconvenient e.g. rats, sprucebudworm, weeds, mosquitos, etc.

) Pesticides are most often used to benefit humans by protecting a valuable species from aless useful organism e.g., protecting crops from damaging caterpillars. At least 30% ofthe crops in Canada are lost each year to pests. Without using pesticides, this would bemuch higher and our losses would be too great. In NL, we spray our forests to protect itfrom pests such as the Larch sawfly and the Hemlock Looper, which destroy our trees.

) pesticides are used to control disease - carrying organisms such as the Anophelesmosquito which transmits the disease Malaria to humans in tropical countries. Malaria isstill one of the diseases that cause the most deaths in the world in underdeveloped tropicalcountries.

) Some history of pesticide use:First Generation Pesticides:- 500 BC - sulfur used to repel insects- 15 century - arsenic, lead and mercury applied to crops. Later they found outth

that these substances were harmful to humans too and stopped using them.- 1763, French gardeners used nicotine sulfate to kill aphids- in 1800's, extracts from the head of the chrysanthemum, a natural pesticide, was

being used.

Second Generation Pesticides:- chemicals made in a lab; not natural compounds found in nature. Thousands of

these have been developed.- note chart, Table 1, p. 53; know the 4 categories of pesticides and their targets.

- some pesticides decompose fairly rapidly so they don’t stay in the environment forlong. However, some stay in the ecosystem for many years. This can causeproblems.


Modern Pesticides:Pros:- soluble in water so can be excreted from the body- more easily broken down in soil

cons:- break down quickly so must be applied more often- not selective; can affect mammals, birds, fish- can be bioamplified when another animal eats several animals carrying large

doses. Although the toxin can be broken down in the liver of animals, a lethaldose may be consumed this way.

T DO - pp. 52 - 53. - items (a) - (b)

Bioamplification - p. 54

bioamplification - a process that results in increasing concentrations of a toxin in the bodiesof consumers at each higher trophic level. (also called Bioaccumulation).

) Pesticides that contain chlorine are soluble in fat but not in water. e.g. DDT, Dieldrin) cannot be excreted from the body as wastes.) accumulate in the fatty tissue of consumers) enters the bodies of animals lower in the food chain.) carnivores start to build up toxin in their body. Every time they eat an animal with a

small amount of poison in it, it bioamplifies in its body until at some point, it reaches atoxic level which harms or even kills the animal.

) affects higher level carnivores the most, especially top carnivores.) the higher the trophic level, the greater the bioamplification.) see figure 4, p. 54 for example - discuss this) humans are also subject to bioamplification. See p. 54 for details.- top or tertiary carnivores are most at risk from bioamplification.

) Assign (e) - ( q), pp. 55 - 57.Also p. 58, # 1,2,3,4,5,7.

DDT - the Worst Bioamplifying Pesticide Ever Used.

DDT was invented shortly after WWII. It is cheap to make and very effective. It is alsolong - lasting and can take years to break down in the environment. It also bioamplifies becauseit contains chlorine and is soluble in fat. It has been banned in Canada and the United States


since the early 1970's because of its terrible affect on bird populations.

Extra Information - Read for interest only:

Some of the greatest effects of pesticides have been on bird populations. Some examplesof what harm the bioamplification of pesticides can do are:

1. was the case of the use of a pesticide called Fenitrothion by New Brunswick tocontrol pests in their forests. Fenitrothion caused a huge death-rate in thesongbird populations of New Brunswick. It was banned from use in NewBrunswick in 1998.

2. Peregrine Falcons almost died out in eastern Canada in the 1960s before thegovernment banned the use of the pesticide DDT in Canada in the 1970's.

3. Another pesticide was recently banned for most uses because as it was responsiblefor the near extinction of the burrowing owl.

4. In the United States, pesticide bioamplification of DDT and other pesticides hasaffected many bird species as well, such as the California Condor, which isendangered. Pesticide residues in the environment have led to eggshell thinningso severe that parents crushed their eggs while incubating. In 1987, there wereonly 29 of them left. The Condors are now in a recovery program.

5. The bald eagle in the great lakes region has declined throughout North America.

) In Canada, more than 30 registered pesticides can poison wild birds.

Why DDT Continues to be a Problem to Us Even Though We Have Banned It

Many third - world countries south of the U.S. border such as Mexico and CentralAmerica, continue to use DDT. Migratory birds such as the Mallard duck, Canada Goose, andPeregrine Falcon winter in Mexico and Central America. While there, they bioamplify the DDTin their bodies and later , are fed upon by predators in our country, which also bioamplify theDDT, causing them harm. DDT has even found its way into the marine food chains due to runoffinto rivers. Even whales bioamplify DDT.

T Students can visit the site http://www.cws-scf.ec.gc.ca/hww-fap/pesticides/pest.html - to read up onthe effects of pesticides on birds.

http://www.cws-scf.ec.gc.ca/hww-fap/pesticides/pest.html


Forest Insect Pests in Newfoundland.

Insect pests that have caused the most damage in NF:

defoliator - a pest that eats the leaves or needles off trees.

1. Eastern Hemlock Looper.- most damaging pest to our forestry.- causes complete defoliation (loss of leaves/needles) of balsam fir in one year.

2. Balsam Woody Adelgid.- injects saliva into trees causing deformed twig growth, and slows bud growth.- no really good treatments for this pest.

3. Spruce Budworm.- is a defoliator in the caterpillar stage.- feeds mostly on fir trees.- can kill a tree over a number of years.- one of the most destructive forest pests in North America

- .

Some Methods of Pest Control

1. chemical - the use of chemical pesticides.2. Biological - using diseases or predators of the pest to control them. e.g. Bt is

sprayed on the forest to kill budworm or loopers, parasitic fliesintroduced, etc.

(a) B.t. - a biological pesticide spray that contains a type of bacteriawhich kills the caterpillars of spruce budworm and larchsawflies.

(b) tachnid flies from British Columbia were introduced to our foreststo kill the looper. They are parasites on the looper caterpillars

(c) experimenting with a type of wasp that is a parasite on thebudworm - thinking of introducing them to Nfld to control theirpopulation

3. Pheromones - are chemical message scents given off by insects to attract mates. Traps are baited with artificially produced pheromones. Thisattracts the males into the trap. With fewer males to fertilize thefemales’ eggs, the population soon drops.


T Do: Debate: p. 81 -82. The tent Caterpillar - should we use pesticides.

The Cycling of Matter - read pp. 50 -51, 60 - 71.

To understand how matter cycles through ecosystems, you must understand the cycling oforganic substances in living things. The materials stored in living things comes from a limitedamount of matter. Therefore, all matter must be recycled. This recycling of matter involves thecarbon, oxygen and nitrogen cycles as well as the role of decomposers. All matter tied up in thebodies of organisms must be decomposed and recycled. ( see fig. 3, p. 51)

organic substance- compound that always contains carbon and hydrogen atoms, andoften oxygen and nitrogen atoms. e.g. proteins, sugars, fats

6 12 2 4e.g. C H O , CHinorganic substance - compounds that don’t contain a combination of hydrogen

and carbon.

2 , e.g. CO 2H O

- write caption from fig. 3, p, 51 into notes

T students do q 1, 5, p. 51

The Carbon Cycle - read p. 62 - 64

) carbon is the main atom of all living things. In inorganic form it mainly exists as carbon

2dioxide gas in the air. CO is also dissolved in sea water.) plants use carbon during photosynthesis to make carbohydrates. This takes carbon from

its inorganic state and transforms it into organic compounds. This carbon then getspassed up the food chain

) carbon is returned to its inorganic state when organisms digest food to get energy. Consumers use sugars in a cell reaction process called cellular respiration. Cellularrespiration requires oxygen. This reaction releases energy to the body and gives offinorganic carbon dioxide to the air. Decomposer organisms also release carbon dioxideto the air

) some carbon has become buried as coal. This carbon is locked away out of circulationunless humans release it by burning fossil fuels (gas, oil, coal). These fossil fuel deposits,the ocean and boglands are huge reservoirs of carbon which are released slowly to theatmosphere.


Man’s Impact on the Carbon Cycle; How We have altered it and its Effect onthe Environment - read p. 64 - 65

students highlight this small section on impact, . Key points are:

2) the level of CO in the atmosphere is rising quickly way beyond normal levels. This isdue to:

1. carbon released from natural reservoirs faster than normal due to burning of fossilfuels, burning forests.

22. less CO being removed due to removal of plants to clear land for agriculture,


forestry or building.

The result has been global warming.

global warming - a warming trend in our climate caused by excess greenhouse gasessuch as carbon dioxide.

Greenhouse gas - any atmospheric gas that traps heat and adds to the greenhouseeffect. e.g. carbon dioxide.

2CO in the atmosphere provides a natural“greenhouse effect”. It traps reflected solar

2energy and warms the earth. However, since humans have increased the amount of CO in theatmosphere, we are causing too much heat to be trapped and it is changing our weather patternsand climate. The average global temperature is rising.

T Do questions p. 65, # 1, 2, 4, 6, 7 (a) (b) (c).

i show video resource on Global Warming.

� students complete question sheet on the Global Warming video andplace it in their portfolios.


The Nitrogen Cycle - read pp. 66 - 67.

Nitrogen is needed by all organisms to make proteins (tissue) and DNA. 79 % ofthe air is nitrogen gas but plants and animals cannot get their own nitrogen from the air. Only

3plants can use inorganic forms of nitrogen such as nitrates, NO , found in the soil or dissolved-

in water, and extract the nitrogen in them to use in making their own plant proteins. Allconsumers must consume other organisms to get their proteins. When organisms die, thenitrogen present in the proteins of living things gets recycled back into inorganic forms such asammonia, nitrites and nitrates by the processes of decomposition and denitrification.

1. Nitrogen - fixation stage

nitrogen fixation - the process of converting free atmospheric nitrogen into nitrates.

3Nitrogen gas in the atmosphere gets converted into nitrates, NO . These are absorbed by-

the roots of plants. This can occur in two ways:(1) lightning in the atmosphere - causes nitrogen in the air to react with

oxygen to form nitrates.(2) Nitrogen - fixing bacteria - give off nitrates as a waste product. Some

nitrogen fixing bacteria are free - living but many live in the roots ofcertain plants called legumes. They supply the legume plants with a steadysupply of nitrogen in return for shelter in the roots and food. Legumesinclude beans, alfalfa and clover - type plants.

2. Decomposition stageDecomposer bacteria decay dead organisms. They break down the proteins in the dead

organisms to produce ammonium. Other bacteria in the soil convert ammonium into nitrites. Another type of bacteria convert the nitrites into nitrates, becoming available again for plant use.

3. Denitrification stage

Some of the nitrates in the soil is converted back into free nitrogen gas by certain bacteriacalled denitrifying bacteria. This returns nitrogen to the atmosphere.


Man’s Impact on the Nitrogen Cycle; How We have altered it and its Effecton the Environment read p. 70.

We are adding extra nitrogen to many environments in the form of fertilizers andpollution wastes from many industries. Human sewage is often released into rivers with littletreatment(e.g. Montreal into the St. Lawrence River) and act as fertilizer. Normally, there is abalanced amount of nitrate in an aquatic ecosystem. However, in areas near agricultural landswhere lots of fertilizers are used, runoff into rivers have caused the levels of nitrate in lakes to gettoo high. This causes a process called eutrophication - pollution making a lake richer innutrients. If the level of nitrate gets too high, an algal bloom can occur. This is where the algaepopulation grows out of control, scumming over much of the lake’s surface. The algae, too manyin number, block much of the light from reaching other plants growing underwater. Also, whenthe algae die, the decomposer bacteria in the water have lots of food. This causes theirpopulation to increase. All this extra decomposition uses up much of the dissolved oxygen in thewater. This is very unhealthy to the ecosystem. It has a bad effect on many species, causing theirnumbers to decline. Fish and other aquatic animals may begin to die.

- DO - see bottom of p. 70: How can nitrates harm humans andother animals?

T Do -questions, and Also, p. 69, # 1 - 4 and p. 71, # 3,4


What is being Done to Reduce Our Impact on the Carbon Cycle - GlobalWarming

� Do - This should be completed by students as a portfolio entry. Itshould be titled “What we are doing to Stop Global Warming”

Global Warming Video Portfolio Entry

Title: “What We Are Doing to Stop Global Warming”

Resource: Earth at Risk; Global Warming - video.

S Give a brief discussion of why Global Warming is a problem. Makemention of present day and possible future consequences.

S propose solutions; note what we are doing now to stop global warming.S discuss other future solutions and what we could be doing to stop global

warming.

The Oxygen Cycle

Oxygen is cycled between the atmosphere and living (biotic) things. Oxygen is used inthe process of cellular respiration by both plants and animals. Carbon is released in the form of

2CO as a waste product of this reaction.

2Plants take in the inorganic gas CO and use it in the process of photosynthesis to make

6 12 6organic sugars such as glucose, C H O . Oxygen is released as a waste product of the photosynthesis reaction.

The reactions of cellular respiration and photosynthesis are reciprocals of each other. Thereactants of one reaction are the products of the other reaction.

Photosynthesis:

2 2 6 12 6 2CO (g) + H O (l) º C H O (s) + O (g)

cellular respiration:

6 12 6 2 2 2C H O (s) + O (g) º CO (g) + H O (g)


Reaction Reactants Products

PhotosynthesisCarbon dioxide + water

2 2CO + H O

glucose sugar + oxygen

6 12 6 2C H O + O

Respirationglucose sugar + oxygen

6 12 6 2C H O + O

Carbon dioxide + water

2 2CO + H O

Human Impact on the Oxygen Cycle:

Deforestation is the major impact by man. Trees are the earth’s largest oxygen -

2producing plants. Plants give off O to the atmosphere through photosynthesis. The destruction

2 2of forests lowers the amount of CO which is being converted into O . The reduction in trees is aone of the contributing factors to global warming.

DO: Case Study : The Effects of Deforestation on Cycling

p. 72 - 73 do items (b) - (g). Also do Q. on p. 73, # 1 - 3.


The Biomes of Canada (read pp. 88 - 92)

Biome - a collection of ecosystems that are similar or related to to each other , usually bythe types of plants present in the area.

There are 4 biomes present in Canada:

1. Tundra2, Boreal Forest3. Temperate Deciduous Forest4. Grasslands

Tundra:

p. 88 - Know Table 1, p. 89Also:- permafrost and active layer- why no trees frow there- dominant plants?- why slow decomposition rate?- why few animal species are present

Boreal Forest Biome:

- know table 2, p. 90- Also:- dominant plants : conifers ( needle - leafed trees which produce cones) eg. spruce,

fir, pine.p. 89 - makes up 80% of forests in Canada

- explain why soils are acidic here- explain how conifers are adapted to the extreme climate here

p. 90 - explain why food available in this to animals living in the lower layer of thisbiome is limited

Temperate Deciduous Biome: pp. 91 - 92

p. 93 - know Table 3, p. 92

p. 91 - know where its locatedp. 91 - why is there faster decomposition here than in the Boreal?p. 91 - Why do more plants grow under the large trees of this biome than in the Boreal?


p. 91 - Why can the temperate deciduous forest support more many more animals thanthe Boreal forest?

p. 91 - Describe the layers present in the temperate deciduous forest. Compare this to theBoreal Forest.

p. 91 - Why does the temperate deciduous forest contains greater biodiversity than theBoreal forest?

Grassland Biome:

p. 93 - know Table 4

p. 92 - Grasslands are at a similar latitude as the Temperate deciduous forests but aredifferent in terms of their dominant plants. Explain why.

p. 92 - Explain why trees don’t tend to grow on the grasslands.

p. 92 - Explain why the grassland soil is the most fertile soil in the world.

p. 92 - Explain why the biodiversity of grasslands is low in comparison to the TemperateDeciduous forest and the Boreal forest.

/DO: questions, p. 93 - # 1 - 5, 8

The Effects of a Dry Summer on a Bogland EcosystemBogs are essentially very large bodies of water, only just held together either by a mixture

of spagnum moss, existing peat, geological characteristics and other vegetation. A bogland relieson rainfall for its source of water. Bogs have a high water table maintained directly by rain andsnow. There may be no rivers supplying a bog.

A dry season is devastating to boglands. Many creatures rely on the wetlands forreproduction. For example, frogs reproduce here. Many insects also breed in the water.Tadpoles may die if their aquatic habitat dries out before they have metamorphosed. In any hotdry summer there are inevitably going to be accidental fires which can result in the loss ofhabitat. This can happen to the upper layers covering bogland if the surface becomes dried out.

/DO: The Great Lakes Case Study

p. 140 - do all items, (a) to (m)also do Q. on p. 142, # 1, 2(a) and 3.(a).

diversity in ecosystems - unit 1millsesdnl.weebly.com/.../sci._1206-_unit_1_notes.pdf ·...

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