ecosystems unit - gci - grade 10 science - home you observe an ecosystem, we see many different...

Dynamics of Ecosystems Grade 10 Science Glenlawn Collegiate

1 | P a g e U n i t N o t e s

Ecosystems Unit

Have you ever wondered where the substances from which you and other living things are made come

from? Why do they not run out? Where do the chemicals that we spray on the ground and on plants to

control pests go after they are applied?

When you observe an ecosystem, we see many different organisms. The population of a given type of

organism, like a rabbit, seems to remain fairly constant. Many other creatures eat rabbits. Why do the

rabbits not disappear? What happens if a new creature that eats rabbits appears in an ecosystem?

Humans interact with ecosystems. Humans need food, water, energy and shelter. The resources for

these are found in the ecosystems in which humans live. What kind of effect do human beings have on

ecosystems? How can humans use the resources but still allow the ecosystem to sustain itself and

humans for the centuries to come? Who makes the decisions about how resources should be used? How

are these decisions made? Do you have a role in this process?

In this unit, you will examine the complex relationships present in an ecosystem. As you study the

dynamics or the workings of an ecosystem, you will obtain answers to these questions.



Lesson One: Introduction to Ecosystems

All life on earth is _________________________. While it might not always feel that way, it has always

been true. Mufasa, from the Lion King, described it accurately: Mufasa - "Circle of Life"

While Disney’s movie didn’t go into detail regarding the scientific nature of this circle of life, the

following Unit will. How is our planet ____________________? How do organisms _____________one

another? Where does all the stuff that makes up life come from? How does it get _________________?

Is our earth _________________________? How does ____________________

____________________affect our planet?

This Unit will answer these questions and will examine the ____________________ relationships

present in ecosystems in order to further investigate issues of _________________________ and the

impact we as ____________________ our having on our planet.

Outcomes After completing this lesson you will be able to:

Explain the difference between ____________________, ____________________ and

____________________

Provide examples of _______________and _______________ factors

Explain the difference between _______________ and _______________

Describe the roles of ___________________, __________________ and __________________

Key Words

abiotic factors

autotroph

biotic factors

consumer

decomposer

detritivore

ecologist

ecology

ecosystem

habitat

heterotroph

niche

producer

Video: Intro to Ecosystems

http://www.youtube.com/watch?v=bW7PlTaawfQ

http://www.youtube.com/watch?v=o_RBHfjZsUQ



Interactions Among Living Things

The branch of biology that deals with the study of the interactions among organisms and with their

environment is known as ____________________. Scientists who study ecology are called

____________________. Because our planet has many diverse plants, animals and environments,

ecologists tend to study smaller areas called ____________________. Examples of ecosystems are:

____________________; ____________________; ____________________ and __________________.

An ecosystem consists of the physical environment (____________________ ____________________)

and all the living things (____________________ ____________________) within it.

On the following table, brainstorm with a partner or group and try to list both abiotic and biotic factors

within the physical environment.

Abiotic Factors Biotic Factors

Everything has a Role

Each type of living thing in an ecosystem has place in which it lives. This is known as its

____________________. The combination of the job an organism does and the place in which it lives is

called its ____________________. What are some jobs that organisms do? Plants and algae trap the

energy in sunlight and produce their own food. Because of this, they are known as

____________________. Another name for a producer is ____________________ which is an organism

capable of _________________________ (creating) its own food from inorganic substances such as

sunlight. Think of “_______________”-troph as an organism that can “_______________”-matically

produce its own food from the sun!



Animals are ____________________ since they cannot make their own food and must obtain their food

from producers. Another name for a consumer is _________________________ which is an organism

that obtains its energy for growth by eating other heterotrophs or autotrophs.

Bacteria and fungi are ____________________. They eat dead plant and animal remains and convert

them into substances that can be reused. They are the ____________________ of the ecosystem. They

belong to the family of organisms called _________________________which are organisms that

consume dead material and animal wastes.

Summary

_________________________ is the branch of biology that deals with the study of the

interactions among organisms and with their environment.

The living things within an ecosystem are known as ___________________ factors and non-

living things within an ecosystem are known as __________________ factors.

Each type of living thing in an ecosystem has place in which it lives. This is known as its

____________________. The combination of the job an organism does and the place in which it

lives is called its ____________________.

Another name for a producer is _________________________ and another name for a

_________________________ is heterotroph.

______________________ belong to the family of organisms called ______________________.



Exercise #1

1. What would happen to an ecosystem if all the decomposers were destroyed?

2. One student argues that humans are producers because they produce their own food by growing crops and raising livestock. Do you agree? Why or why not?

3. Create an Ecosystems Dictionary from the Key Words using the following two pages.



Lesson Two: Energy Flow

All ____________________ need energy to carry out the activities of life such as moving, feeding,

reproducing, and growing. Only _______________ are able to take energy from the sun and use it to

drive their activities. Most organisms cannot take the energy from the sun and use it directly for their

own purposes. Instead, they eat other ____________________ to obtain their ____________________.

Since organisms only eat certain other types of organisms, the trail of the energy can be traced as it

flows along from organism to organism.

Outcomes

After completing this lesson you will be able to:

Describe the roles of __________________, __________________ and ___________________

Explain the difference between a food _______________ and a food __________

Draw a food web found in a local ____________________

Describe how _______________ flows through an ecosystem

Key words

carnivore

ecological pyramid

food chain

food web

herbivore

omnivore

primary consumer

pyramid of energy

scavenger

secondary consumer

tertiary consumer

trophic level

What’s the Big Idea?

Right now, even sitting there at your desk, you are using energy. Your heart is pumping, your diaphragm

muscle is flexing to help you breathe, even your brain reading these words is using energy. Where did

you get that energy? Think about your recent meals. If you ate an apple, that apple had energy in it that

it got from somewhere. Every living thing requires energy to live. This lesson is about the movement of

that energy throughout an ecosystem.



Food Chains

Since all living things require _______________ to live, the ultimate source of that energy is the

__________. Producers such as _______________ and _______________ capture the sun’s energy and

transform it into organic compounds. These compounds are used to build plant parts such as leaves and

flowers, or store extra energy in roots and seeds.

Unlike producers, ____________________ are unable to directly transform sunlight into organic

compounds. ____________________ ____________________ (also called ____________________)

feed directly on plants. Examples of herbivores include moose, cattle, grasshoppers, rabbits and aphids.

____________________ ____________________ feed on primary consumers, and _________________

consumers feed on secondary consumers. These higher-level consumers are also known as

____________________. Examples of carnivores include wolves, northern pike, eagles, polar bears,

ladybugs and snapping turtles. ____________________ are carnivores that feed on dead animals.

Examples of scavengers include blowflies, turkey vultures, eagles, seagulls and ravens. Where do we

humans fit because many of us eat both plant and animals? We, along with black bears and red-wing

blackbirds are _______________ because we feed on both _______________ and _________________.

Each step in this series of feeding relationships is known as a _______________ _______________.

Producers and consumers are linked together in _______________ _______________, a sequence of

organisms through which energy is passed. Here is an example of a food chain in the Lake Winnipeg

ecosystem consisting of four trophic levels:



Food Webs

Because animals typically feed on more than one type of organism, food chains become connected in a

complex relationship known as a ________ __________. The carnivore at the top of the food chain/web

is called a top carnivore. The diagram below shows the food web of the Lake Winnipeg ecosystem.

The arrows show how the sun’s energy flows through an ecosystem from the sun, to

____________________, to ____________________, and to ____________________. Because plants

and animals die at all points in food chains, decomposers are found at all trophic levels in ecosystems.



Ecological Pyramids

Ecologists use ____________________ ____________________ to describe the energy flow among the

trophic levels. You can visualize the total amount of incoming energy at each level in an ecosystem as a

____________________ of ____________________. The area at the bottom of the energy pyramid

represents the greatest amount of energy in an ecosystem. As the energy passes from

____________________ to ____________________, less is available each successive trophic level.

Pyramid of Energy

All the energy originates in the __________. Only __________ of the energy is passed on from one

_______________ level to another. This is because all of the energy that an organism takes in is not

transformed into food. Energy is used by the organism for a variety of life processes such as breathing,

transporting materials, movement, reproduction, and so on. Only a portion of the energy used goes into

building organic compounds. As a result, about 10% of the energy taken in at one trophic level is passed

on to the next level. Less and less _______________ is available to organisms higher up the food chain.

This explains why there are seldom more than four or five _______________ levels in a food chain.



Summary

Food chains consist of ____________________ and ____________________, which are connected into

__________ __________. Energy flows through ecosystems from one _______________ level to the

next.

Exercise #2

1. Why is it more energy efficient for humans to eat grains and vegetables rather than meat?

2. Why is sunlight needed to maintain an ecosystem?

3. Draw a food web based on an ecosystem of your choosing. Be sure to include at least two

producers, two primary consumers, one secondary consumer and one tertiary consumer.



Lesson Three: Carbon & Oxygen Cycle

While energy flows in a one-way direction through an ecosystem, ____________________ are recycled

over and over again. _________________________ ____________________ are the processes by which

nutrients move through organisms and the environment. You may be familiar with the water cycle in

which water moves from the Earth’s atmosphere to the surface (_________________________), and

back to the atmosphere again (_________________________). Other important nutrients that are

recycled are ____________________, ____________________ and ____________________. This lesson

will focus on the carbon and oxygen cycle.

Outcomes


Explain how ____________________ is cycled through an ecosystem

Explain how ____________________ is cycled through an ecosystem

Create a diagram of how the carbon and oxygen cycle _______________

Key Words

biogeochemical cycle carbon cycle carbon sink

cellular respiration glucose oxygen cycle

photosynthesis

Carbon Cycle

The process by which carbon moves through an ecosystem is called the ____________________

____________________. Producers such as green plants and algae take in a carbon-containing nutrient

known as ____________________ ____________________ from the atmosphere. The chemical formula

of carbon dioxide is __________. This process is called _____________________________.



The chemical formula for photosynthesis is:

During _________________________, the energy of the sun is used to convert carbon dioxide into

_______________, a type of organic compound. Plants then change glucose into other types of carbon

compounds. The chemical formula for glucose is __________. When animals eat plants and algae, the

carbon compounds are converted into glucose. The glucose is then converted into carbon dioxide and

energy in a process known as ____________________ ____________________.

The chemical formula for cellular respiration is:

The energy is used by organisms for growth, movement, reproduction, excreting wastes, digesting food,

and so on. The carbon dioxide is released into the atmosphere, and the cycle continues.



Areas that naturally or artificially store large quantities of carbon containing compounds are known as

_______________ _______________. Examples of natural carbon sinks are ____________________,

and ____________________. Artificial carbon sinks would include ____________________ and

____________________ ____________ _________________________.

Oxygen Cycle

The ____________________ ____________________, which moves

oxygen through an ecosystem, is closely linked to the carbon cycle.

Plants use water during photosynthesis and release oxygen gas into

the atmosphere. The chemical formula for oxygen gas is __________.

Organisms then use the oxygen gas during cellular respiration and

release water into the atmosphere. The cycle continues as plants

produce oxygen during photosynthesis, which is then used by

organisms in cellular respiration.



Summary

In this lesson you have studied the ____________________ cycle, the ____________________ cycle.

These biogeochemical cycles are the means by which nutrients move through organisms and the

environment. These cycles allow ____________________ to be recycled over and over again. In the next

lesson we will examine how ecosystems are affected when nutrient cycles are ____________________.

Exercise #3

1. Compare and contrast the terms “photosynthesis” and “cellular respiration”. How are they the same?

How are they different?

Summary statement that defines these terms:

2. Write the chemical formula for photosynthesis:

3. Write the chemical formula for cellular respiration:

What do you notice? (compare/contrast #2 and #3.)



4. Use the space provided to draw the Carbon Cycle:



Lesson Four: Disturbing the Carbon Cycle

The Carbon Cycle transports ____________________ from the atmosphere to the land and water and

back into the atmosphere. The carbon found in the atmosphere can be thought of as money in a bank

account. _________________________ removes carbon dioxide from the atmosphere, much like you

would make a withdrawal from your bank account. ____________________

_________________________ and combustion return carbon dioxide to the atmosphere. This is like

depositing money in the bank account. If you deposit more money than you withdraw, your bank

account balance increases. In a similar fashion, if more carbon dioxide is returned to the atmosphere

than is used up, the amount of carbon dioxide in the atmosphere increases.

Outcomes


List sources of ____________________

Describe how ____________________ events may disturb the carbon cycle

Describe how ____________________ activities may disturb the carbon cycle

Suggest ways in which we can reduce the flow of carbon dioxide into the atmosphere.

Key Words

combustion fossil fuels deforestation

Sources of Carbon

As you recall from the carbon cycle lesson, ____________________ remove carbon dioxide from the

atmosphere and use it to produce ____________________ in the process of photosynthesis. The

glucose is then used by organisms and turned into carbon dioxide and energy in a process known as

_________________________ _________________________.

_______________ and ____________________ can convert glucose into other types of carbon

compounds. For example if we eat more food than we need to supply us with energy, our bodies change

the glucose and other carbon compounds into fat. Plants convert glucose into starches and oils to store

their excess energy. Plants also change glucose into ____________________, an important component

of wood and other plant fibres.

Disturbing the Carbon Cycle: Natural Events

The cycling of carbon can be disturbed by ____________________ ____________________. Forest fires

are one example. The _________________________, or burning of plant material such as wood releases



large amounts of ____________________ ____________________ into the atmosphere. Similarly, the

burning of leaves and stubble in the fall increases the amount of carbon dioxide in the atmosphere.

____________________ can disrupt the cycling of carbon. Volcanic activity can break down rocks

containing carbon compounds and release carbon dioxide into the atmosphere. The ash generated from

a volcano can also block ____________________ from reaching the Earth’s surface. This may reduce the

amount of _________________________ done by plants. This in turn could cause the amount of carbon

dioxide in the atmosphere to increase.

Disturbing the Carbon Cycle: Human Activities

The cycling of carbon can be disturbed by ____________________ activities.

_________________________ is the cutting down of forests. Forests are cleared to create more land for

farming and to allow towns and cities to grow. Deforestation has ____________________ the amount

of ____________________ available for photosynthesis. Fewer plants mean that less carbon dioxide can

be removed from the atmosphere.

When plants and animals die, their remains usually ____________________, and the carbon contained

in them is released back into the atmosphere as carbon dioxide. On occasion, plant animal remains

break down very slowly. The carbon from the remains is stored in the Earth and become fossil fuels. The

____________________ ____________________ such as gasoline, coal and natural gas that we burn to

produce energy also release carbon dioxide into to Earth’s atmosphere. The energy is then used to heat

our homes and run our automobiles and factories.

The amount of carbon dioxide in our atmosphere has _________________________ in the past 150

years. This corresponds to our increased use of fossil fuels for home heating, transportation, and

production of goods by industry. There is a concern that the increased amount of carbon dioxide in the

atmosphere will lead to ____________________ _________________________.

What can we do?

How can we reduce the flow of carbon dioxide into the

atmosphere? We can try to reduce the effects of

__________________________ by planting more trees

and shrubs in our yards. We can also

___________________ paper and building materials so

that fewer trees need to be cut down.

We can reduce our consumption of _____________________ ___________________ in our homes. This

can be accomplished in many ways. We can turn down the thermostat in the winter. We can add

_________________________ to the attic. Old windows and doors can be replaced with newer ones. By



making our homes more energy efficient, we can reduce the amount of home heating oil and natural gas

that we use, thereby decreasing the amount of _________________ __________________ we produce.

We can reduce our consumption of fossil fuels used in _________________________. Skateboarding,

cycling or walking to meet friends produces much less carbon dioxide than does driving an automobile.

A large vehicle such as a SUV, minivan or pickup truck is less energy efficient than a sub-compact or

compact car. Large vehicles with large engines produce more carbon dioxide than do small cars with

small engines.

Summary

The ____________________ ____________________ is actually very delicately balanced. If the

amount of carbon dioxide released into the air by ____________________

_________________________ and _________________________ of organic material and fossil

fuel exceeds the amount removed from the atmosphere by _________________________ in

plants, the carbon dioxide accumulates in the atmosphere. This contributes to the

_________________________ ____________________. Since the population of the earth is

now so large, the effects of deforestation, that is removing trees that use carbon dioxide, and

the increased amount of combustion for heating homes and industry, ____________________

____________________ now plays a significant role in the Carbon Cycle. Each of us must act in

a manner that will reduce the amount of carbon dioxide spewed into the atmosphere.

Exercise #4

1. List and describe two “natural events” which affect the carbon cycle:

List and describe two “human activities” which affect the carbon cycle:



2. What do you think are some of the obstacles that stand in the way to reducing human

disruption of the carbon cycle?

3. Some Canadians are not concerned about global warming. How would you respond to someone

who thinks global warming would be great because it would make our winters shorter and not

as cold?



Lesson Five: Nitrogen Cycle

Nitrogen is absolutely essential for us and every other organism on the planet (no life without it). The

problem is that while most of the air we breathe is nitrogen (78%), most life forms can’t use it in this

form. This is very similar to water. There is water vapour in the air, but we still need to drink liquid water

to survive. This lesson will look at ways that nitrogen turns from a gas to a “usable” solid, and back to a

gas again (that’s the cycle).

Outcomes

Explain how ___________________________ is cycled through an ecosystem

Differentiate between _____________________________, ________________________ and

______________________________

Discuss the importance of ____________________ ____________________ in ecosystems

List sources of human-introduced nitrates

Describe the consequences of algal blooms

Key Words

nitrogen wastewater nitrogen cycle ammonium fertilizer nitrogen fixation denitrification legume nitrification agricultural runoff nitrate algal bloom

Nitrogen Cycle

Nitrogen is an important nutrient found in all living things and is used to build proteins. The process by

which nitrogen moves through an ecosystem is known as the __________________ ________________.

While nitrogen gas makes up about __________ of the Earth’s atmosphere, most living things cannot

use it in this form. The chemical formula for atmospheric nitrogen gas is __________.

So how does it become usable? Certain ____________________ can change nitrogen gas into

____________________. The process is known as ______________________ and it mostly occurs in the

_________________________________. This is where the nitrogen fixing bacteria live. Legumes include



clover, alfalfa, beans, and peas. A small percentage of nitrogen fixation is done by free-living soil

bacteria. But we’re not done yet, because ammonium is not usable by plants. First ammonium needs to

be converted to _____________ (NO2), then to ______________ (NO3) by different kinds of bacteria

(nitrifying bacteria) living in the soil. This process is called _________________________. All plants then

can use nitrate to produce a variety of plant proteins.

This process of turning N2 gas into usable nitrate is essential to re-cycling nitrogen on our planet.

A relatively small amount of N2 is converted into usable nitrate by ________________________ because

lightning is powerful enough to break the bonds of N2. This is called ______________________________

and contributes approximately 5% of the total nitrogen fixed.

When animals eat plants, they convert plant protein into animal protein. For example, when you eat

bread, beans, pasta or any other foods containing plant matter, your body converts the protein into

muscle, hair, fingernails and other animal proteins. When you eat meat, your body also converts the

animal proteins into the proteins your body needs. When plants and animals die, decomposers break

down the nitrates into ammonium, which needs to go through the nitrification process to be taken up

again by plants and used to make proteins.

Other bacteria will convert nitrate and ammonium back into nitrogen gas in a process is known as

______________________________. This process also occurs when bacteria convert animal waste (e.g.

sewage), and plant waste (e.g. dead leaves) into nitrogen gas.

In all of the examples of the Nitrogen Cycle, notice the processes of _______________ ______________

and ____________________________ are required to maintain the cycle. Nitrogen fixation is required

to change atmospheric nitrogen (N2 gas) into a solid form plants can use (NO3). Denitrification takes

nitrogen from nitrates (NO3 solid) and returns the nitrogen to the atmosphere (as N2 gas).



Disturbing the Nitrogen Cycle

What we have seen so far is what the nitrogen cycle looks like in a world without human interference.

Many human activities can throw off the nitrogen cycle just like we saw when looking at the carbon

cycle in the last lesson.

Humans add nitrogen to the environment in many ways such as _____________________________,

_____________________________________, human and farm animal feces, agricultural and

_________________________________. These additions can’t be denitrified (turned into atmospheric

nitrogen, or N2) as quickly as they are being added. Because of this, they often end up in our waterways.

Why is this a Problem?

Algae is a type of simple plant that lives in water. In a balanced ecosystem, algae is limited in its

reproduction. However, if you have warm water, sunlight, and add enough nutrients like nitrogen, algae

will overwhelm a lake or pond. This is called an __________ _____________. The blooms can produce

toxins that can kill fish and other wildlife that drink the water. The toxins can irritate your skin if you

swim in it and drinking the water or eating fish from contaminated water can cause upset stomach and

diarrhea. You may recall that Grand Beach is often closed for a period of

time in mid-late summer because of algal bloom toxins being present in

high concentrations. Lake Winnipeg algal blooms are considered the

worst of any freshwater lake in the world!

(NO3)



Summary

_________________________ is an important nutrient found in all living things and is used to

build proteins.

Nitrogen gas makes up about _______ percent of the earth’s atmosphere.

Most living things _________________________ use atmospheric nitrogen.

Certain _________________________ that live in the roots of ____________________ plants

can “fix” nitrogen gas into _________________________

The chemical formula for:

o atmospheric nitrogen is __________

o ammonium is __________

o nitrate is __________

o nitrite is___________

Lightning fixes only about _______ percent of atmospheric nitrogen.

Denitrifying bacteria break down nitrates and convert them back into nitrogen gas. The process

is called _________________________________.

If we add to much nitrate to the environment, it usually ends up in our ____________________.

Excess nitrates in the water can lead to ____________________, which can create

_______________ harmful to wildlife and humans.

Exercise #5

1. Why is nitrogen important?

2. Why do you think farmers alternate planting clover and alfalfa with their wheat and canola crops? This isn’t in your notes! You have to think this out. (hint: clover and alfalfa are part of the legume family!)

3. Consider algal blooms:

Identify 4 human activities that contribute to algal blooms.



Identify 2 human activities that should not take place in waters in which an algal bloom is occurring. Explain why.

4. Use the image provided and fill in the blanks in the follow questions:

i. What type of bacteria is found at stages B and C? _____________________

ii. The product of the bacteria from question i. that can be found at stage D: ________________

iii. The type of plant-usable nitrogen at stage F is called: _________________

iv. What type of bacteria are found at stage G? ____________________

v. What process is done by the bacteria from question iv.? ____________________

ecosystems unit - gci - grade 10 science - home you observe an ecosystem, we see many different...

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