Dynamics of Ecosystems Grade 10 Science Glenlawn Collegiate

Transcription

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

2 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 2 P a g e U n i t N o t e s

3 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! 3 P a g e U n i t N o t e s

4 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 nonliving 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. 4 P a g e U n i t N o t e s

5 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. 5 P a g e U n i t N o t e s

6 6 P a g e U n i t N o t e s

7 7 P a g e U n i t N o t e s

8 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. 8 P a g e U n i t N o t e s

9 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: 9 P a g e U n i t N o t e s

10 10 P a g e U n i t N o t e s

11 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. 11 P a g e U n i t N o t e s

12 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. 12 P a g e U n i t N o t e s

13 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. 13 P a g e U n i t N o t e s

14 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 After completing this lesson you will be able to: 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. 14 P a g e U n i t N o t e s

15 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. 15 P a g e U n i t N o t e s

16 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. 16 P a g e U n i t N o t e s

17 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.) 17 P a g e U n i t N o t e s

18 4. Use the space provided to draw the Carbon Cycle: 18 P a g e U n i t N o t e s

19 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 After completing this lesson you will be able to: 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 19 P a g e U n i t N o t e s

20 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 20 P a g e U n i t N o t e s

21 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: 21 P a g e U n i t N o t e s

22 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? 22 P a g e U n i t N o t e s

23 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 23 P a g e U n i t N o t e s

24 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 (N 2 gas) into a solid form plants can use (NO 3). Denitrification takes nitrogen from nitrates (NO 3 solid) and returns the nitrogen to the atmosphere (as N 2 gas). 24 P a g e U n i t N o t e s

25 (NO 3) 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! 25 P a g e U n i t N o t e s

26 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. 26 P a g e U n i t N o t e s

27 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.? 27 P a g e U n i t N o t e s