INTERACTIONS WITHIN ECOSYSTEMS CLASS NOTES FOR GRADE 7

INTERACTIONS WITHIN ECOSYSTEMS CLASS NOTES FOR GRADE 7 SCIENCE MS. RAPOSO - 2018

CHAIN OF EVENTS (PAGE 1 OF 3) • Even before these chicks learn how to fly, they dive off 15 -storey-high cliff sides into the cold, dark water of the Hudson Bay in Canada’s North. • This begins a two-month journey for the young, thick-billed Murres, first swimming, and then flying, to Labrador where they spend their winters. • The scientist shown in the picture to the right is interested in learning about living things in their environment. • In order to learn more about the lives of thickbilled Murres, she has to band the chicks now, when they are easily caught because they have not yet learned to fly.

CHAIN OF EVENTS (PAGE 2 OF 3) • In the small photograph, Peregrine Falcon chicks are being placed in the nest of a pair of Peregrine Falcons that have not been able to produce their own young. • Peregrine Falcons were close to extinction in Eastern Canada in the mid-1900 s following the common use of the pesticide, DDT. • Why? The use of this pesticide had some unfortunate side effects. • One negative effect was that it caused the egg shells of many kinds of birds to become so thin and fragile that their chicks did not survive. • DDT is no longer used in Canada as of 1990. • The ban on the use of DDT, and programs such as the one shown here, to help Peregrine Falcons achieve nesting success, are increasing the numbers of this majestic bird. • Peregrine Falcons are making a comeback and can be seen today nesting on tall buildings in Canadian cities. • Originally, Peregrine Falcons nested on cliff sides, but now they also use buildings for their nest – a human-made substitute.

CHAIN OF EVENTS (PAGE 3 OF 3) • How do living things interact with one another? • How do they interact with the non-living parts of their environment? • How do we, as humans, fit in, and what should we do to ensure that Earth remains a planet full of life? • These are topics you will explore in this unit. • Please refer back to your notebook and complete the Chain of Events section with a partner.

ORGANIZATION OF LIFE (PAGE 1 OF 3) • The picture on the right displays the Organization of Life in order. • Please copy the information down and be prepared to read and learn about each level in the next slides in this section of this Power. Point Presentation.

ORGANIZATION OF LIFE (PAGE 2 OF 3) • A community is filled with groups of organisms that interact with each other, but it does not exist on its own. • It has boundaries, and it is affected by external conditions, such as the average amount of sun and rain, and the average temperature. • An ecosystem is the interactions between abiotic features of an area and the biotic community that lives in the area. • An ecosystem includes individuals, populations, and communities, and more. • An ecosystem can be large or small, but it must contain all the abiotic and biotic features of the area. • For example, a rotting log is an ecosystem, as long as all the organisms living in or on the log and all the abiotic factors affecting the log are included. • In the same way, a forest is an ecosystem, as long as it includes all the biotic organisms living in it, as well as the abiotic features affecting it. • Usually the environment is the same across an ecosystem, so that it gets the same amount of rain or sunshine.

ORGANIZATION OF LIFE (PAGE 3 OF 3) • An ecosystem also has fairly clear physical or environmental boundaries. • For example, the edge of a ploughed field would physically mark the edge of a pond ecosystem, • An environmental boundary could be the edge of an area that gets more sunshine or rain, or a change in altitude along the side of a mountain. • Biomes and Biospheres are the last two levels of the organization of life, however, they will be looked at more closely in the unit.

NICHES AND FOOD WEBS (PAGE 1 OF 17) • The role of organisms in food chains has several levels. • Look at the plants in the food chains in the picture. • Green plants and algae contain a chemical called chlorophyll. • Chlorophyll traps the energy of the Sun, in order to create food through photosynthesis. (You will learn more about the process of photosynthesis later). • Plants and algae are called producers because they produce food for themselves and others, using the Sun’s energy and nutrients in the soil and air. • At the beginning of every food chain, there must be a producer. • Producers make life possible for all other organisms on Earth.

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NICHES AND FOOD WEBS (PAGE 3 OF 17) • All other organisms are called consumers, because they consume (eat) the food made by the producers. • Consumers come in all sizes and shapes and include grazing animals, fish, and animals that eat other animals. • Look at the picture of the food chain. (Previous slide). • The organism next to the producer always feeds on plants or algae. • Plant-eating animals are called herbivores. • Cows, snowshoe hares, deer, herring, and tadpoles are examples of this group of consumers. • The picture to the side showcases Artic herbivores – in winter, these musk oxen scrape through the snow to find lichen, grass, and moss to eat.

NICHES AND FOOD WEBS (PAGE 4 OF 17) • The next organism in the food chain eats the herbivore. • These meat-eaters are called carnivores. Take a look at the picture. (This is also secondary consumers – carnivores that only eat herbivores). • Canada lynxes, cod, minnows, and dragonflies are examples of carnivores. • The carnivore at the end of the food chain is known as the top carnivore. • Sometimes the top carnivore feeds on other carnivores: for example, a hawk preys on smaller, insect-eating birds. • In some cases, the top carnivore may also feed on herbivores: the lynx eats snowshoe hares, and the wolf eats moose. • The next page will display a complex ecosystem.

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NICHES AND FOOD WEBS (PAGE 6 OF 17) • Predators are animals that kill and eat other animals called prey. • Hawks and wolves are examples of predators. • Predators usually eat only meat; however, some will eat almost anything if food is in short supply. • Such animals, including bears and dogs, are called omnivores. • How would you describe your place in the food chain?

NICHES AND FOOD WEBS (PAGE 7 OF 17) • The clean up squads: Scavengers and Decomposers • Have you ever wondered why you seldom see a dead carcass in a natural environment? • If dead organisms stayed whole, the earth would soon be covered in all different types of bodies! • In every community, there must be a “clean-up squad” that gets rid of garbage and sewage. • In a biological community, the clean-up squads are consumers called scavengers and decomposers.

NICHES AND FOOD WEBS (PAGE 8 OF 17) • Scavengers: • Many different organisms help to remove carcasses. • Scavengers are organisms that eat dead or decaying plant or animal matter. • For example, Carrion Beetles dig under the body of a dead bird or mammal, causing it to sink into the ground, as shown in the picture. • The Carrion Beetles then lay their eggs in the carcass. • What a legacy these beetles leave for their young – a huge supply of meat! • Similarly, Snails act as scavengers when they eat dead fish in an aquarium. • Snails can also act as herbivores when they eat living plants and algae. • Gulls act as scavengers when they eat dead material washed ashore along a beach. • Gulls are also carnivores when they eat earthworms in a freshly ploughed field.

NICHES AND FOOD WEBS (PAGE 9 OF 17) • Decomposers: • Have you ever seen old food in your refrigerator go mouldy? • If so, you have witnessed decomposers at work. • Decomposers differ from scavengers in that they do not actually eat dead material. • Instead, they break down dead or waste material, such as rotting wood or manure. • Decomposers like the ones in the picture, absorb some of the nutrients from the broken-down material into their own cells. • The remaining nutrients recycle back into the ecosystem. • Many bacteria and fungi are decomposers. • Although bacteria are micro-organisms (too small to see without a microscope), some fungi are quite large and visible. • In fact, you can see common fungi called mushrooms in any grocery store or vegetable market.

NICHES AND FOOD WEBS (PAGE 10 OF 17) • Decomposers (continued): • Though many decomposers are micro-organisms, they play major roles in everyday life. • A scientist name Alexander Fleming observed that bacteria did not grow near moulds. • His observations were used to develop penicillin, an antibiotic that fights disease-causing bacteria. • People use their knowledge of how micro-organisms work in other beneficial ways, too. • For example, moulds are used to ferment blue cheese, while bacteria are used to make sauerkraut and are added to milk to make yogurt. • Yeast is another type of micro-organism, used to make bread dough rise. • Do you think people who were first offered blue cheese or yogurt knew what they were eating? • Decomposers also play a key role in breaking down much of our kitchen waste. • We can assist this process by composting lettuce leaves, apple cores, carrot peelings, and other kitchen wastes in a composter. • When we compost, we let nature’s decomposers turn our kitchen wastes into rich soil we can use for fertilizing the garden.

NICHES AND FOOD WEBS (PAGE 11 OF 17) • Did you ride your bike to school today? • Did you play a sport in gym class? • Have you ever mowed the lawn or shovelled the snow? • Do you sleep, breathe, grow? • All of these activities require energy, and to get energy you must take in food. • Food contains stored energy, but how did the energy get there in the first place? • Grass and other plants grow by using energy from the Sun and nutrients in the soil as sources of food. • The energy of the Sun is then “stored” in plants. • When an animal, such as a cow eats a plant, it obtains the Sun’s energy indirectly in a useful form. • When a meat-eating animal (perhaps a person sitting down to a steak diner later consumes the cow), the energy is passed on to the consumer.

NICHES AND FOOD WEBS (PAGE 12 OF 17) • A food chain is a model which shows how energy stored in food passes from organism to organism. • The picture on the bottom shows some examples of food chains, in different ecosystems. • In a food chain, arrows show the direction in which energy flows through the chain.

NICHES AND FOOD WEBS (PAGE 13 OF 17) • Energy Flow: • How does energy move through a food chain? • At each step along the chain, energy is taken in by an organism. • Some of this energy fuels the organism, and it is burned up and released as heat. • Some energy is stored in the organism’s body tissues, while some energy cannot be used and passes out of the animal as waste. • For example, when a grazing cow eats several kilograms of grass in one day, it does not gain mass equivalent to the mass of the grass it eats. Why not? Take a look at the picture on the next slide. • About 4 percent of the stored energy in the grass goes to build and repair the cow’s body tissues. • A little over 30 percent fuels the cow’s normal activities, such as breathing, mooing, and pumping blood through its body. • Much of the grass (over 60 percent) cannot be used by the cow and passes out of its body as waste. • Only 4 percent that is used to build and repair the cow’s body stays in the cow’s body tissues. • This is the “stored” energy, and it becomes available to the organism that eats the cow. • You can see most of the energy in the grass eaten by the cow is not passed along the food chain.

NICHES AND FOOD WEBS (PAGE 14 OF 17) • Energy flow is the movement of energy, starting from the Sun, and passing from one organism to the next. • In a food chain, as you saw with the cow, very little energy that is stored in one organism is passed on to the next organism.

NICHES AND FOOD WEBS (PAGE 15 OF 17) • Niches in a Community: • You, like all other members of human communities, play several different roles in your daily life. • When you are at school, you are a student. • On the weekend, you might be a member of a sports team, dance club, or another organized activity group. • The organisms in a community of plants and animals play different roles, too. • Each of these roles is known as a niche. • One organism usually fills several niches. • For instance, snails can act as both scavengers and herbivores, and gulls can be both scavengers and carnivores. • To understand an organism’s niche, you must look at what it eats, where it lives, and how it interacts with other organisms in its ecosystem.

NICHES AND FOOD WEBS (PAGE 16 OF 17) • Food Webs: • Food chains are rarely as simple as the models you saw in the earlier slides of this Power. Point Presentation. • Producers are usually eaten by many different consumers, and most consumers are eaten by more than one kind of predator. • For example, a mouse, which may have eaten several kinds of plants and seeds, may be eaten by a hawk, a raccoon, or a snake. • The raccoon may also eat berries, frogs, and birds’ eggs. • A network of inter-connected food chains is called a food web. (Shown in the picture on the next slide). • To draw a food web for a community, you can begin by drawing the food chains in the community. • Next, look for organisms that are common to more than one of these food chains. • Perhaps grass, a producer, is found in several chains. • Grass can then be used to link the two chains together. • Food webs, understandably, can quickly become very large and very complex. • Once you’ve observed the picture on the next slide, you can begin your food chain assignment.

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SYMBIOSIS (PAGE 1 OF 3) • Sometimes when organisms of different species live in the same ecosystem they live more closely than one would think. • Organisms of different species that live together for an extended period of time are said to be a symbiotic relationship. • Symbiosis – an interaction between two organisms of different species living in close proximity that lasts over time. • Types of Symbiosis: • Not all symbiotic relationships are the same. There are three distinct types: • Parasitism – A symbiotic relationship in which one of the partners is harmed and the other benefits. • Mutualism – A symbiotic relationship in which both partners benefit. • Commensalism - A symbiotic relationship in which one partner benefits and the other is indifferent.

SYMBIOSIS (PAGE 2 OF 3) • Imagine a great white shark cruising toward you through tropical waters. • As a human, your only thought would be to get away (and fast). • Yet one small fish, called a remora, cannot get close enough! • It uses suckers on its head to attach itself firmly to the shark’s skin and then dines on bacteria and microorganisms that are unhealthy for the shark. • The odd association between the large, fearsome shark and the little remora is an example of a symbiotic relationship. • In Parasitism, typically, one of the partners lives on or in the other organism and feeds on it. • External parasites, such as the louse are often very small and so they are able to hide in hair, fur, or feathers. • Some internal parasites are microscopic. • The malaria-causing parasite Plasmodium lives and reproduces inside the human red blood cell. • Other internal parasites such as the tapeworm grow to be very large. • The organism that provides food for a parasite is called the host. • Typically a parasite does not kill its host (if it did, it would die as well), but it often weakens its host by taking nutrients away, and thus shorten its host’s life.

SYMBIOSIS (PAGE 3 OF 3) • In Mutualism, termites have mutualistic relationship with single-celled micro-organisms, called protozoa. • These micro-organisms live in the digestive tracts of the termites since they cannot break down the wood they consume to get the nutrients on their own. • The protozoa digests wood. • The termites live on the protozoa’s waste products. • This relationship is mutually beneficial – although it is not beneficial to the humans whose homes termites eat! • In Commensalism, one partner benefits and the other partner does not appear to lose or gain from the relationship. • Clownfish and sea anemones have this type of relationship. • Clownfish live among the poisonous tentacles of the hosting anemone. • The fish gains safety and eats scraps left over from the anemone’s dinner. • There is no obvious benefit or cost to the anemone.

CYCLES IN THE BIOSPHERE, WATER FLOW AND CARBON CYCLE (PAGE 1 OF 6) • The water cycle • All living things require water. • Water is used for life processes such as supplying food throughout an organism’s body in a form it can use in its cells, and carrying away wastes from those cells. • The water cycle is the continuous movement of water through the biosphere. • There are four main processes in the water cycle: • Evaporation – process of changing a liquid into a vapour (gas) • Transpiration – process in which water that is taken in through a plant’s roots evaporates from the plant’s leaves, stems, and flowers • Condensation – process of changing a vapour to a liquid • Precipitation – process in which liquid water forms from condensation occurring inside clouds, and then falls as rain, sleet, snow, and hail

CYCLES IN THE BIOSPHERE, WATER FLOW AND CARBON CYCLE (PAGE 2 OF 6) • We know that living things, including you, need oxygen to survive. Have you ever wondered how scientists figured this out? • In the late 18 th century (1700 s), scientists discovered that a mouse could not survive in a closed container in which a candle had been burned. However, when a plant was left to grow in the container for eight or more days, a mouse could survive. The burning candle used up all the oxygen in the container, so there was no oxygen available for the mouse to breathe. • The carbon dioxide and oxygen cycle is the process by which carbon dioxide and oxygen are cycled and recycled in the biosphere. • When you breathe, you take in oxygen. Your body cells use this oxygen, in a process called respiration, to release energy from food. • Respiration is the oxygen-using process, that takes place in the cells of living things to get the energy out of food. • All living things –both animals and plants- must respire all the time. • Fish and algae respire in water. So do decomposers such as bacteria, fungi, yeasts, and moulds.

CYCLES IN THE BIOSPHERE, WATER FLOW AND CARBON CYCLE (PAGE 3 OF 6) • In addition to energy, respiration has two other products: carbon dioxide and water. • Carbon dioxide is a gas made up of carbon and oxygen. • Plants need carbon dioxide, along with other substances, to make their own food in a process called photosynthesis. • In some ways, photosynthesis is the reverse of respiration because the plant takes in carbon dioxide and releases oxygen.

CYCLES IN THE BIOSPHERE, WATER FLOW AND CARBON CYCLE (PAGE 4 OF 6) • Humans often use technologies to change ecosystems in order to meet their own needs. • For example, the people in a community might benefit from damming a nearby river. • What might be the positive effects for the community? Any negative ones? • Redirecting water flow can have major effects not only on a moving fresh-water ecosystem and the ecosystems immediately surrounding it, but also on ecosystems that are farther away. • For example, when birds, animals, and other organisms are forced to leave an area because a dam is built, they must try to survive elsewhere. • This causes competition between these birds and animals with the new ecosystem they had to find. • When areas that were previously covered by tress are cleared, the soil can be washed away by run -off. • This process of moving soil and rock from one place to another is called erosion. • If the reservoir that is formed by damming a river is large, an area downwind could receive more rain, snow, and other precipitation. • This occurs because there is a larger accumulation of water to evaporate, condense, and fall.

CYCLES IN THE BIOSPHERE, WATER FLOW AND CARBON CYCLE (PAGE 5 OF 6) • Fossil fuels are fuels that originated from plants and other organisms that died and decomposed millions of years ago and were preserved deep under the ground. • Fossil fuels are products of plankton that lived millions of years ago. • Plankton are microscopic plants, algae, and other organisms that float in seas and other bodies of water. • Phytoplankton are plankton, such as algae, that use sunlight to make their own food through photosynthesis. • Millions of years ago, decomposing plankton were repeatedly buried under layers of mud and silt that, with time and pressure, became rock. • Carbon is necessary for all life to exist. • Plants use carbon dioxide from the air for photosynthesis, and moose, mice, and other organisms eat the plants. • They respire, releasing carbon dioxide into the air. • Wolves, foxes, and other organisms eat the moose and mice, and they also respire, releasing carbon dioxide into the air. • In this way, carbon cycles around in an ecosystem.

CYCLES IN THE BIOSPHERE, WATER FLOW AND CARBON CYCLE (PAGE 6 OF 6) • Imagine stepping into a greenhouse on a sunny but cool day. The air inside the greenhouse is much warmer than outside because most parts of the Sun’s rays pass through the glass walls of the greenhouse. These rays are taken in by the soil and plants. Energy released by the soil (called heat radiation) travels back up to the top of the greenhouse, but this type of energy cannot easily pass through the glass. The trapped energy warms the air in the greenhouse. • The atmosphere surrounding Earth acts like the glass walls of a greenhouse. • It allows sunlight to pass through to Earth’s surface, and prevents much of the returning heat radiation from passing back out into space. • This is one reason why Earth is warm enough for life to exist. • Without the atmosphere, Earth would be too cold to support most species. • The glass of a greenhouse prevents some of the heat radiation from escaping, so the air in the greenhouse warms up. • This same effect is occurring in our atmosphere. • Greenhouse gases are gases, such as carbon dioxide, that result from the burning of fossil fuels as well as other fuels, such as wood. • These gases add to the heat-trapping effect of the atmosphere, forming a “covering. ” • This “covering” cause the atmosphere to hold in more heat radiation then it would naturally. • A gradual warming of Earth’s atmosphere was known as Global Warming – it is now associated as Climate Change.

REGULATED ECOSYSTEMS (PAGE 1 OF 1) • This page is from former students of mine. I simply took information they did and merged it together to provide you an idea and better understanding of each topic so you can form your own ideas. How does _______ help or hurt an ecosystem? • Climate Change • • • Different climates help different places Rising sea levels Causes death of animals and plants Global warming and cooling Ice caps are melting Natural disasters • Competition for Resources • Animals are a part of most human diets • Some animals will starve if other animals eat their food • Forest Fires • • Smoke pollutes the air Lose oxygen-producing trees Can spread quickly Creates an opportunity for new plants • Predator/Prey Populations • Number in both populations is always changing • Some species are endangered • Diseases and Parasites • Lowers population • Spreads amongst organisms

REFERENCES • Galbraith, D. , Gue, D. , Bullard, J. , Clancy, C. , Kiddel, B. A. (1999). Science Power 7: Science, Technology, Society, and Environment. Mc. Graw-Hill Ryerson Limited, Toronto. • Mc. Kay, R. , Wiebe, J. , et al. (2013). Pearson Science 7: Manitoba Edition. Pearson Canada Inc. , Toronto.