Unit Chunk 4A – Transfer of Energy Through Ecosystems

Day 1 – Transfer of Energy Through Ecosystems – Part 1An ecosystem is a collection of all the living organisms—biotic factors—that live in a particular habitat (e.g. pond, forest, desert) together with their nonliving environmental components—abiotic factors. Without a constant input of energy, living systems cannot function.Biotic factors + Abiotic factors = an Ecosystem

Sunlight—solar energy—is the main energy source for life on Earth.Inorganic chemical compounds are another important energy source for life on Earth.EQ: What are the two main sources of energy for life on Earth?

Many different organisms can capture energy directly from sunlight or from inorganic chemicals, and they use that energy to produce their own carbon compounds—the energy fuels needed for an organism’s life processes. These organisms are called autotrophs. Because they can make their own carbon compounds for fuel, autotrophs are called producers.Many organisms (like us!) cannot harness energy directly from the sun or inorganic chemicals. Organisms that rely on other organisms for their energy and carbon compounds are called heterotrophs. Heterotrophs are consumers—they cannot produce their own carbon compounds for fuel and must consume other organisms to get the CCs that they need.There are many different types of heterotrophs/consumers.

• Herbivores eat plants/algae. • Carnivores eat animals.• Omnivores eat both plants and animals.• Detritivores feed on plant and animal remains and other dead

matter. • Decomposers like bacteria and fungi, break down organic matter

and waste.

Autotrophs, producers, can capture energy directly from sunlight or from inorganic chemicals, and they use that energy to produce their own carbon compounds.Heterotrophs, consumers, cannot harness energy directly from the sun or inorganic chemicals. They rely on other organisms for their energy and carbon compounds.EQ: Distinguish between autotrophs and heterotrophs.

Day 2 – Transfer of Energy Though PhotosynthesisMost autotrophs harness solar energy through the process of photosynthesis.During photosynthesis, autotrophs use visible light energy to convert carbon dioxide, CO2, and water, H2O, into oxygen, O2, and stored chemical energy in the form of glucose, C6H12O6.EQ: Define the process of photosynthesis.

Photosynthesis is responsible for adding oxygen to and removing carbon dioxide from Earth'satmosphere and ocean. Photosynthesis occurs in plants, algae, and in some eukaryotes, prokaryotes, and animals.Some autotrophs can produce CCs in the absence of sunlight.  When organisms use chemical energy to produce carbon compounds, the process is called chemosynthesis.

Green plants are the principal autotrophs on land.

They use the energy of visible sunlight to make the organic molecules O2 and C6H12O6 from H2O and CO2.

EQ: What is the chemical equation for photosynthesis? What are the reactants and products for photosynthesis?

Visible Sunlight 6 CO2 + 6 H2O ® C6H12O6 + 6 O2 Reactants Products

sunlightcarbon dioxide + water ® glucose + oxygen

CO2 and H2O are the reactants. O2 is the waste product, and C6H12O6 is the product that is stored chemical energy. The purpose of photosynthesis is to make glucose--stored chemical energy!The Law of Conservation of Matter states that atoms of matter can neither be created nor destroyed—they are rearranged in a chemical reaction. The total number of reactant atoms must equal the total number of product atoms. And this is exactly what happens in photosynthesis—the molecules change, but the atoms remain the same!!!

EQ: Develop and label a model to illustrate how photosynthesis converts light energy into the stored chemical energy of glucose. * The organelles, chloroplasts, are the sites for photosynthesis.* The reactant CO2 enters through the plant’s leaves, and the reactant H2O enters the plant through its roots. * The energy source, visible light, is captured by chlorophyll, pigment molecules in the chloroplasts. This light energy fuels the chemical reaction.* The captured energy splits the H2O molecules. Oxygen becomes a waste product, and the charged hydrogen atoms begin a series of chemical reactions that create high energy molecules that react with the CO2 to make higher energy molecules that finally produce a single molecule of glucose--C6H12O6. * The waste product, O2, exits through the plant’s leaves, and the main product, C6H12O6, exits the chloroplast is used as stored chemical energy wherever it is needed inside or outside the cell. C6H12O6, glucose, the simple sugar product of photosynthesis, is the source of virtually all energy for life on our planet, and provides most of the building material for living organisms. This monomer is the building block for other complex carbohydrates (sucrose, lactose, ribose, cellulose, and starch) that move into the other cells of the plant, and if the plant is eaten, move into the cells of the consumer.

Day 3 – Transfer of Energy Through Ecosystems – Part 2

Energy flows through an ecosystem in one direction--from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers). Energy flows in one direction with a LOSS of energy from one organism to the next.EQ: How does energy flow through an ecosystem?

A food chain is a single set of energy transfers--a single set of steps--in which organisms transfer energy by eating and being eaten.

A food web is how energy flows through many organisms in an ecosystem. Webs show how organisms obtain energy from many different sources, and also provide energy to many different organisms. A food web links all the food chains in an ecosystem together. In a food web, the arrow shows the energy flow and always points to the consumer.EQ: Distinguish between a food chain and a food web.

Trophic LevelsEach step in a food chain or food web is called a trophic level.Producers make up the first trophic level. These autotrophs can harness energy directly from the sun or inorganic chemicals.Consumers make up the second, third, or higher trophic levels. These heterotrophs depend on the trophic level below them for their energy. EQ: Why are producers the first trophic level?

Trophic Levels for Terrestrial Ecosystem

Day 4 – Transfer of Energy Through Ecosystems – Part 3The amount of energy or matter in an ecosystem can be represented by an ecological pyramid. An ecological pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level. An Energy Pyramid shows the relative amount of energy available at each trophic level.Only part of the energy (about 10%) that is stored in one trophic level is passed on to the next level. This is because 90% of the energy is lost at each level. EQ : About how much energy is transferred at each trophic level? EXPLAIN.

EQ: Which trophic level has the most energy? EXPLAIN.Producers at the first trophic level have the most energy. These autotrophs can harness energy directly from the sun or inorganic chemicals.

EQ: Which trophic level has the least energy? EXPLAIN.Consumers at the highest trophic levels have the least energy. Because there is only about a 10% energy gain at each trophic level, these higher-level heterotrophs receive very little energy from each organism they consume. Elimination of a species or the introduction of a new species changes the energy flow in an ecosystem.

EQ: Why are there fewer organisms at the top trophic levels?Higher-level consumers receive very little energy from each organism they consume.They must consume large amounts of lower-level heterotrophs to get enough energy, and there is usually a limited number of these animals in any ecosystem.

Unit Chunk 4B – Transfer of Matter Through Ecosystems

Day 1– Transfer of Matter Through EcosystemsEnergy and matter move through ecosystems very differently. Unlike the one-way flow of energy, matter is recycled within and between ecosystems in our biosphere.

Matter can cycle through the biosphere’s ecosystems because molecules of matter are neither created nor destroyed--their atoms are rearranged into different molecules. Biogeochemical cycles pass the same atoms around again and again within the biosphere.EQ: How does matter cycle through ecosystems in the biosphere?

The Carbon CycleCarbon, the most important atom of carbon compounds, is a key ingredient of all living organisms. There are three processes that move carbon atoms through their cycle in our ecosystems: biological processes, geochemical processes, and human processes.

Biological processes, such as photosynthesis, cellular respiration, and decomposition, capture and release carbon dioxide and oxygen.*Geochemical processes, such as erosion and volcanic activity, release carbon dioxide into the atmosphere and oceans.*Human processes - the burning of fossil fuels, such as wood, charcoal, and oil (gasoline), releases carbon into the air that combines with oxygen to form carbon dioxide.

The Carbon Cycle• Plants on land and phytoplankton in oceans (producers) take in CO2 during

photosynthesis, and release O2 into the atmosphere and ocean. This provides consumers on land and in the ocean with O2.

• During cellular respiration, consumers take in O2 and release CO2 back into the atmosphere and ocean.

• The world ocean provides an even exchange of CO2 and O2.

• The decomposition of all living organisms releases CO2 back into the atmosphere.• Erosion and volcanic activity release CO2 back into the atmosphere.• Fossil fuels and carbonic rocks in the ocean store carbon.

EQ: Develop and label a model to describe the cycling of carbon among the hydrosphere, atmosphere, geosphere, and biosphere.

Day 2 – Anthropogenic Carbon CycleThe Anthropogenic Carbon Cycle--Human Alteration of the Carbon Cycle1. The burning of fossil fuels (coal, oil, natural gas) by humans releases C that combines with O2 in air to form CO2 increasing C levels in atmosphere & ocean.2. Human activities as agriculture and waste disposal release methane (CO4) into the air, increasing carbon levels in our atmosphere.3. Deforestation by humans, which destroys the principal organisms that can absorb excess CO2.4. CO2 emissions caused by human activities increase ocean acidification which kills the organisms that take in CO2, reducing the ocean’s ability to absorb excess CO2

Because of these human activities, atmospheric CO2 levels are higher today than they have been over the last half-million years or longer.

Greenhouse gases carbon dioxide, methane, water vapor, and other gases in the atmosphere allow solar radiation (sunlight) to enter the biosphere. Much of this sunlight hits the Earth’s surface, is converted into heat energy, and is radiated back into the atmosphere. The greenhouse gases trap much of this heat, not allowing it to pass out of the atmosphere. The Greenhouse Effect is what controls our Earth’s climate and keeps it at perfect temperatures for life to exist!EQ: Describe the Greenhouse Effect.

CLIMATE CHANGE* Climate change has always fluctuated in the Earth’s history due to natural events. With the exception of natural mass extinctions, most of these natural changes in climate are slow enough for organisms in an ecosystem to adapt and evolve and survive. * The recent climate change produced by human-created excess carbon emissions, like the burning of fossil fuels and deforestation, is occurring very rapidly. We are producing an excess amount of Greenhouse gases that are trapping in more and more heat. This is known as anthropogenic climate change.

* The result is extreme weather conditions, the extinction of species and entire ecosystems, the dominance of both invasive and destructive species, and an increase of excessive natural disasters based on these events--forest fires, flooding, drought, hurricanes, typhoons, tornadoes, loss of coastal lands and islands.

A CARBON SINK is anything that absorbs more CARBON than it releases. Trees, vegetation, the ocean, the atmosphere, the soil, and buried fossil fuels are all natural carbon sinks. BUT—we are burning fossil fuels at an alarming rate, AND we are destroying our forests and vegetation, AND the excess CO2 in the Earth’s atmosphere is affecting the world ocean’s ability to absorb carbon. A CARBON SOURCE is anything that releases more CARBON than it absorbs. The main carbon source created by humans is the burning of fossil fuels for manufacturing everything we use (gasoline, electricity, gas, houses, clothes, food, electronics, appliances, PLASTICS, etc.) AND the daily operation for most of these.EQ: Distinguish between a carbon sink and a carbon source & provide examples of each.Fossil fuels are LIMITED natural resources!Biodiversity and Ecosystems are LIMITED natural resources directly affected by climate change!How is the carbon cycle today—the anthropogenic carbon cycle—different from the natural carbon cycle?

EO: Construct an explanation based on scientific evidence for how Earth’s systems, the environment, and biodiversity are being effected due to human activity.