Living Environment Ecosystems Ecosystems Full of Matter, Energy, and Entropy 2017-07-18 www.njctl.org
Table of Contents: Ecosystems Full of Matter, Energy, and Entropy Click on a topic to go to that section Review of Living Systems What is an Ecosystem? Recycled Matter: Nutrient Cycles The Flow of Energy Through Ecosystems Entropy Summary
Review of Living Systems Return to Table of Contents
Review: Living Systems Recall that a system is a collection of parts that work together to accomplish a function. A living system is one that has the 6 unifying principles of life. The cell is the most simple, fundamental living system. Therefore, all living things are made up of cells.
Review: Open and Closed Systems An open system is one that is able to exchange energy and matter with its surroundings. A closed system cannot exchange matter with its surroundings, and an isolated system cannot exchange energy or matter with its surroundings. In real life, there is no perfect closed systems. A device like a Thermos that keeps your coffee warm is close, but it is not perfect (your coffee will cool, eventually).
Review: Living Systems are Open Systems Living things cannot live without energy. Inanimate objects, such as rocks, can exist without using energy, but life cannot. Therefore, all living things are open systems. You have demonstrated that you are an open system by eating, talking, walking, and excreting wastes. All of this is exchanging matter and using energy - it flows into you through what you eat, and it flows out of you in the form of heat.
What is an Ecosystem? Return to Table of Contents
What is an Ecosystem? Ecosystems are groups of living things living together in a community, and the nonliving, physical environment that they live in. As we have discussed, every living thing is a system. And the nonliving environment is a system as well. An ecosystem is a collection of individual living systems, all interacting to form the larger ecosystem.
Why Study Ecosystems? Ecologists study the interactions of living things within ecosystems. They study populations of organisms to understand how they change over time and make predictions on how they will change in the future. Humans are part of the ecosystems on earth. We cannot live independently of ecosystems. Therefore, we need to understand how ecosystems stay healthy so we can all do our part in ensuring a good future for all living things. In addition, economies depend on ecosystems. Understanding ecosystems helps us to use our natural resources most effectively and in sustainable ways.
Recycled Matter: Nutrient Cycles Return to Table of Contents
Nutrient Cycles Energy constantly radiates from the sun to the earth and is transformed into forms of energy living organisms can use to sustain life. However, organisms need more than energy to survive - they need water, minerals, and the chemical compounds like carbon dioxide and oxygen that allow photosynthesis, respiration, and other essential chemical reactions to take place.
1 The cycling of nutrients through an ecosystem would be considered what type of factor? A Abiotic B Biotic Answer
Nutrient Cycles Biogeochemical cycles refer to the pathways through which a chemical moves through the biosphere. The primary biogeochemical cycles studied in ecology are: Water Cycle Carbon Cycle Nitrogen Cycle Phosphorous Cycle
Nutrient Cycles Primary producers like plants typically obtain nutrients from their environment. Consumers obtain nutrients by eating other organisms. Carbon, nitrogen, and phosphorous are all key nutrients that cycle through the biosphere.
The Water Cycle Water is essential to living organisms. Click the picture above to watch a video about the water cycle.
The Water Cycle Most water molecules are taken up into the clouds by evaporation and transpiration. The water returns to the oceans, lands, and lakes by precipitation. Water that enters the soil returns to the oceans through runoff.
2 Describe the direction of water molecules during transpiration. A oceans to atmosphere B atmosphere to oceans C atmosphere to plants D plants to atmosphere Answer
3 Water that enters the soil returns to the ocean via what process? A Precipitation B Runoff C Condensation D Transpiration Answer
The Carbon Cycle Click the picture above to watch a video about the carbon cycle.
The Carbon Cycle Carbon is moved through the biosphere in four main ways: Photosynthesis, cellular respiration and decomposition in living organisms take up and release carbon. Geochemical processes like erosion and volcanic activity release CO 2 into the atmosphere and the ocean. Burial and decomposition under pressure converts dead organisms into fossil fuels like coal and petroleum, storing carbon underground. Human activities like mining, forest fires and the burning of fossil fuels release CO 2 into the atmosphere.
The Carbon Cycle Summary: Most carbon is found in the atmosphere. Carbon is used by plants to form sugars, which are eaten by animals. Carbon is recycled to the atmosphere by cellular respiration. Human activities like burning of fossil fuels also release carbon into the atmosphere.
4 Most carbon is found A as carbon dioxide. B in plants. C in fossil fuels. Answer D as glucose.
5 How is carbon returned to the atmosphere? A Organisms release it during respiration. B It is released during the burning of fossil fuels. C It is released during volcanic activity. Answer D All of the above.
The Nitrogen Cycle Nitrogen is the an important nutrient found in all amino acids. All organisms from bacteria to humans require nitrogen to make proteins.
The Nitrogen Cycle Most nitrogen is found as a gas in the atmosphere, but this form is unavailable for protein synthesis. Bacteria in the soil fix nitrogen so that it can be used by plants and animals. This is called nitrogen fixation.
The Nitrogen Cycle The process of nitrogen fixation occurs due to an amazing symbiotic relationship between a genus of bacteria called Rhizobium and legumes (bean and pea plants). The bacteria live inside plant roots, where they cause the formation of root nodules. They receive nutrients from the plants and, in return, they fix atmospheric nitrogen into a form that can be used by the plants.
The Nitrogen Cycle
6 Animals obtain nitrogen via A ingestion of bacteria. B ingestion of plants. C direct absorption of atmospheric nitrogen. Answer D denitrification.
7 Nitrogen fixation occurs when A plants release nitrogen into the atmosphere. B bacteria convert nitrates into atmospheric nitrogen. C bacteria convert atmospheric nitrogen into ammonium. Answer D decomposers release nitrogen into the soil.
The Phosphorous Cycle
The Phosphorous Cycle Most phosphorous is stored in the form of inorganic phosphate within rocks and sediment until they eventually wear down and release the phosphate. Phosphate molecules can be washed into rivers, streams, and eventually the ocean where they are used by marine organisms. Phosphate that remains in the soil is absorbed into plants that convert them into organic compounds to be useful to living organisms.
8 Most phosphorous is found A in the atmosphere. B in plants and animals. C in rocks and sediments. Answer D in bacteria.
Nutrient Limitation All of the nutrients discussed are necessary to maintain a healthy, productive ecosystem. When a organism's productivity is slowed by one nutrient that is in limited supply, that nutrient is referred to as the limiting nutrient.
Nutrient Limitation: Fertilizers Nitrogen and phosphorous are limiting nutrients for most plants. To ensure the highest productivity from crops, farmers apply fertilizers that contain nitrogen and phosphorous. If too much fertilizer is applied, however, the extra nutrients are not absorbed by the plants and they remain in the soil. This negatively affects the environment.
Nutrient Limitation: Fertilizers When extra nutrients run out of farmland and into the water supply, it can cause algal blooms. Like plants, algae are also limited in growth by nitrogen and phosphorous availability. When fertilizers run into the water, they are able to grow at higher levels than normal. An algal bloom picture in the Bay of Biscay as seen from a satellite.
Nutrient Limitation: Fertilizers Ecosystems can be damaged by runoff. Rain Fertilized soil runs off field and into aquatic ecosystem (lake). Extra nutrients in fertilized soil stimulate the rapid growth of producers like algae. If there are not enough consumers to eat the algae, algal bloom can occur. The amount of algae in the water reduces the oxygen supply. Reduced oxygen supply results in lower numbers of more complex plants and consumers like fish.
9 A low supply of nitrogen in soil prevents certain crops from growing. In other words, nitrogen is the A limiting reagent. B organic compound. C limiting nutrient. Answer D abundant nutrient.
10 Why would an algal bloom result in lowered fish populations? A Fish have no limiting nutrients. B The fish population is overcrowded. C Algae compete with fish for food. Answer D Fish cannot survive in the reduced oxygen levels created by increased algae.
With your group, discuss how the nutrient cycles keep everything alive within the closed ecosphere. How is this a model for the earth's ecosystem? Revisit: The Ecosphere
The Flow of Energy Through Ecosystems Return to Table of Contents
The Origin of Life Energy All living things need energy. Therefore, energy must flow into an ecosystem and all of the living individuals in the community that is part of that ecosystem. Where does all of this energy come from?
The Origin of Life Energy Recall from physical science and earlier chapters that energy cannot be created nor destroyed. However, it is not recycled. It starts as usable energy and becomes less usable over time. Eventually, all useful energy in universe will become unusable, if it is a closed system. The earth is not a closed system. It cannot exchange much matter with space asides from the meteorites that strike down or the space junk left by space travel. However, it is open for exchange of energy. What kind of energy is able to travel through the vacuum of space and reach earth?
The Origin of Life Energy The sun's light energy can travel through space. This source of energy is ultimately what provides energy for earth's ecosystems. How do you obtain the sun's energy? Can you consume it directly?
Producers are the Link Producers, such as plants and algae, are able to harness the sun's energy directly. Recall from the photosynthesis chapter how producers are able to convert light energy into the chemical energy we know as food energy. Consumers, such as fungi and animals, must consume the producers directly, or eat other consumers for energy. Answer What would happen to a population of consumers if the producers in their ecosystem declined?
Energy Transfers Between Organisms Energy can be transformed from one form to another. On the chemical level, this happens when the chemical bonds between molecules are rearranged. When producers harness light energy, the energy from the light is used to form chemical bonds and make large molecules. When the consumers eat the producers, those molecules are transferred over with the energy in the chemical bonds that they contain.
Food Chains A food chain, like the one below illustrates the flow of energy through ecosystems. http://yyzhang.weebly.com/uploads/1/3/5/5/13554444/8807507_orig.jpg Answer The arrow points in the direction of the energy transfer. Since the insect consumes the plant, the energy is transferred from the plant to the insect. Which organism has the most energy available for it?
Energy Pyramids An energy pyramid, such as the one below, illustrates the relative amount of energy available at each trophic level - a group of organisms that are at the position in the food chain. What happens to the amount of relative energy available as it moves up through the levels? 0.1 1 Answer 10 https://dr282zn36sxxg.cloudfront.net/datastreams/f-d %3Ad3cf63c66c57e9e60008e078035134cfbfad98f752f13f6dc195e179%2BIMAG E_THUMB_POSTCARD_TINY%2BIMAGE_THUMB_POSTCARD_TINY.1 100 1000
11 All of the energy that you use to talk, walk, and breathe originally came to earth from A the last meal you ate. B the sun. C the sugar stored in your liver. D the producers. Answer
12 Which of the following types of organisms are most abundant? A producers B plant eaters C meat eaters Answer D fungi
13 The types of consumers that have the most energy available to them are A plant eaters B meat eaters C scavengers D fungi Answer
14 On a hike through the woods, which type of consumer are you most likely to see? A bear B fox C deer Answer D bobcat
15 In order for a population of 100 frogs to stay stable, there must be a population of at least flies for them to eat. A 50 B 100 C 200 D 2000 Answer
Entropy Return to Table of Contents
Entropy Why does the amount relative energy available decrease as it moves through the food chain and up the trophic levels? Is the energy destroyed? Absolutely not - energy is conserved. However, available, useful, energy is never conserved. Remember entropy from a previous chapter. All available energy will eventually become heat energy that is unavailable for use by living organisms. Yes, it can keep you warm, but you are not using it. It is only slowing the rate at which heat leaves your body and therefore decreases the amount of energy you have to use for your shivering muscles to keep you warm. You are not actually using this heat energy.
Energy Pyramids Let's revisit the energy pyramid. How much energy is escaping as heat when it transfers from level to level? 0.1 1 Answer 10 https://dr282zn36sxxg.cloudfront.net/datastreams/f-d %3Ad3cf63c66c57e9e60008e078035134cfbfad98f752f13f6dc195e179%2BIMAG E_THUMB_POSTCARD_TINY%2BIMAGE_THUMB_POSTCARD_TINY.1 100 1000
Entropy in Ecosystems So the effect of entropy is that available energy decreases as it moves through a food chain. This means that organisms at the top of the food chain have less energy available to them. What effect does this have on populations of organisms at different places in the food chain?
Biomass Pyramids This biomass shows the retalive amount of biomass, or total mass of all the living organisms, at each trophic level. What happens to the relative biomass as the trophic levels increase? https://sites.google.com/a/ssccards.org/nuvia-ecology/13-6-pyramid-models Answer
Entropy in Ecosystems Because of entropy, there will always be less consumers than producers, and there will always be less carnivores than herbivores. Think about how this effects humans. Recall in the beginning of the chapter that economies depend on ecosystems. The most basic part of an economy is the food that is available to people. Discuss with your group how entropy in the food chain affects the human diet, what agriculture does to deal with entropy, and what ultimate affect this has on the ecosystem.
16 As energy moves through an ecosystem, entropy increases. True False Answer
17 The most abundant energy source for the human diet is from A plants B animals C fungus Answer
18 On a long voyage to Mars, is it possible to live off of a garden on board the space craft? A Yes, the plants provide unlimited energy. B Yes, only if there is enough energy on the space craft to power a light source for the plants to use photosynthesis. Answer C No, plants will not provide all of the necessary nutrients. D No, the plants need more carbon dioxide.
19 Which of the following is a practical use of entropy? A building a skyscraper B powering a computer C combusting a fuel-air mixture in an engine Answer D growing a garden
Summary Return to Table of Contents
Summary Ecosystems are open systems. The earth does not exchange a lot of matter with its surroundings, but it constantly receives lifesustaining energy from the sun. Ecosystems are groups of living things and the nonliving environment that they live in. Ecology studies the interactions of these living things and with their nonliving environment. Matter is recycled in an ecosystem. The matter that enters living systems is known as nutrients. > The four main nutrient cycles are the water cycle, carbon cycle, nitrogen cycle, and phosphorus cycle.
Summary The energy needed for all living things comes from the sun. Only a very small amount of microbes can live off of the energy in small inorganic compounds. > Unlike matter, energy does not cycle through an ecosystem. It always flows to a less usable form. In a food chain, the producers have the most amount of useful energy available to them, and are therefore have more biomass. Top level consumers have the least amount of useful energy, and have smaller populations than the lower consumers that they feed off of.