An ecosystem has diverse living organisms. In the study of Ecology, these living organisms are categorized on the basis of the level of organization. So at the basic numbers level we have the population, then we identify the species and community to which that organism belongs, how it interacts with the ecosystem and other organisms in the ecosystem. Scientists have also studied the interaction between different organisms and classified their interactions into different types.This unit will take a minimum of 5.5 hours. Significant Ideas
Big questions:
Knowledge and Understanding 2.2.U1 A community is a group of populations living and interacting with each other in a common habitat
 Community refers to all the populations in a specific area or region at a certain time. Its structure involves many types of interactions among species. Some of these involve the acquisition and use of food, space, or other environmental resources. Others involve nutrient cycling through all members of the community and mutual regulation of population sizes. In all of these cases, the structured interactions of populations lead to situations in which individuals are thrown into life or death struggles.In general, ecologists believe that a community that has a high diversity is more complex and stable than a community that has a low diversity. This theory is founded on the observation that the food webs of communities of high diversity are more interconnected. Greater interconnectivity causes these systems to be more resilient to disturbance. If a species is removed, those species that relied on it for food have the option to switch to many other species that occupy a similar role in that ecosystem. In a low diversity ecosystem, possible substitutes for food may be non-existent or limited in abundance. 2.2.U2 An ecosystem is a community and the physical environment with which it interacts
Everything in the natural world is connected. An ecosystem is a community of living and non-living things that work together. Ecosystems have no particular size. An ecosystem can be as large as a desert or a lake or as small as a tree or a puddle. If you have a terrarium, that is an artificial ecosystem. The water, water temperature, plants, animals, air, light and soil all work together. If there isn't enough light or water or if the soil doesn't have the right nutrients, the plants will die. If the plants die, animals that depend on them will die. If the animals that depend on the plants die, any animals that depend on those animals will die. Ecosystems in nature work the same way. All the parts work together to make a balanced system!Some ecosystems can cross several countries and so their conservation and ecology has an international dimension.
image from naturalscience-5.blogspot.com 2.2.U3 Respiration and photosynthesis as processes with inputs, outputs and transformations of energy and matter.
Photosynthesis should be understood as requiring carbon dioxide, water, chlorophyll and certain visible wavelengths of light to produce organic matter and oxygen. The transformation of light energy into the chemical energy of organic matter should be appreciated. Respiration should be recognized as requiring organic matter and oxygen to produce carbon dioxide and water. Without oxygen, carbon dioxide and other waste products are formed. Energy is released in a form available for use by living organisms, but is ultimately lost as heat. Photosynthesis: inputs:
Respiration: inputs: processes:
2.2.U4 Respiration is the conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy.
Respiration releases energy for cells from glucose. This can be aerobic respiration, which needs oxygen, or anaerobic respiration, which does not.Respiration is a series of reactions in which energy is released from glucose. Aerobic respiration is the form of respiration which uses oxygen. It can be summarized by this equation: glucose + oxygen → carbon dioxide + water (+ energy) Energy is shown in brackets because it is not a substance. Notice that:
Aerobic respiration happens all the time in the cells of animals and plants. Most of the reactions involved happen inside mitochondria, tiny objects inside the cytoplasm of the cell. The reactions are controlled by enzymes. 2.2.U5 During respiration, large amounts of energy are dissipated as heat, increasing the entropy in the ecosystem while enabling organisms to maintain relatively low entropy and so high organization.
Respiration is a chemical reaction where food, water and oxygen is turned into energy for us to use (also allowing us to breathe etc.) In every reaction there are 2 types of energy; useful and wasted. the useful energy is the stuff we want and wasted is the stuff that's just converted accidentally while making the useful energy. it's wasted because energy can't be destroyed or created, just changed. one type of wasted energy that's created in most reactions is thermal, or heat energy. As respiration is a chemical reaction, there are useful energy transfers taking place, however as a byproduct of these reactions heat energy is produced. 2.2.U6 Primary producers in most ecosystems convert light energy into chemical energy in the process of photosynthesis.
Primary producers, also called autotrophs, are organisms that can produce their own food. Most autotrophs lie at the bottom of the food chain, serving as food sources for animals farther up the line. Primary producers are self-sufficient when it comes to meals: they produce their own food using light, carbon dioxide, water and sometimes other chemicals too.Producers (autotrophs) are typically plants or algae that produce their own food using photosynthesis and form the first trophic level in a food chain. Exceptions include chemosynthetic organisms that produce food without sunlight. 2.2.U7 The photosynthesis reaction is can be represented by the following word equation. carbon dioxide + water yields glucose + oxygen
Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar. This process occurs in plants and some algae. Plants need only light energy, CO2, and H2O to make sugar. The process of photosynthesis takes place in the chloroplasts, specifically using chlorophyll, the green pigment involved in photosynthesis.The photosynthesis reaction is can be represented by the following word equation.
2.2.U8 Photosynthesis produces the raw material for producing biomass
Biomass is organic, meaning it is made of material that comes from living organisms, such as plants and animals. The most common biomass materials used for energy are plants, wood, and waste. These are called biomass feed stocks. Biomass energy can also be a non-renewable energy source. Biomass contains energy first derived from the sun: Plants absorb the sun’s energy through photosynthesis, and convert carbon dioxide and water into nutrients (carbohydrates). 2.2.U9 The trophic level is the position that an organism occupies in a food chain, or the position of a group of organisms in a community that occupy the same position in food chains
In ecology, the trophic level is the position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains - what it eats, and what eats it. Ecologists look at a natural "economy of energy" that ultimately rests upon solar energy. When they look at an ecosystem there is almost always some foundation species that directly harvests energy from the sun, for example, grass (however in deep sea hydrothermal vents chemosynthetic archaea form the base of the food chain) 2.2.U10 Producers (autotrophs) are typically plants or algae that produce their own food using photosynthesis and form the first trophic level in a food chain. Exceptions include chemosynthetic organisms that produce food without sunlight.
All life depends ultimately on primary producers, the organisms which capture the energy in sunlight by photosynthesis. On land, they are easily recognized as plants. Although marine primary production by coral reefs, mangroves and seagrasses is relatively better-known, the vast majority of primary production in the sea is by microscopic single-celled plants called phytoplankton. Phytoplankton account for 50% of the oxygen produced An example is photosynthetic plants that make their own food from sunlight (using a process called photosynthesis) and chemosynthetic bacteria that make their food energy from chemicals in hydrothermal vents. These are called autotrophs orprimary producers.2.2.U11 Feeding relationships involve producers, consumers and decomposers. These can be modelled using food chains, food webs and ecological pyramids
All living things need to feed to get energy to grow, move and reproduce. But what do these living things feed on? Smaller insects feed on green plants, and bigger animals feed on smaller ones and so on. This feeding relationship in an ecosystem is called a food chain. Food chains are usually in a sequence, with an arrow used to show the flow of energy. Below are some living things that can fit into a food chain Producer: can make their own food, as they use sunlight to make food and are called the basis of every ecosystem which helps the rest of the species through input of energy and new biomass. This all happens through photosynthesis which is the process when the producer uses the sun for energy. Consumer: feed on other organisms, they do not contain photosynthesis pigments so they cannot make their own food. They have to get energy, minerals and nutrients by eating other organisms. This makes the heterotrophs. Herbivores feed on autotrophs, carnivores on other heterotrophs and omnivores on both. Decomposer: get their food from the breakdown of a dead organism matter. They break down tissue and release nutrients for absorption by other producers. Decomposers also improve the nutrient capacity in the soil by breaking down the organic material.
image from en.wikipedia.org
2.2.U12 Ecological pyramids include pyramids of numbers, biomass and productivity and are quantitative models that are usually measured for a given area and time
An ecological pyramid is an illustration of the reduction in energy as you move through each feeding (trophic) level in an ecosystem. The base of the pyramid is large since the ecosystem's energy factories (the producers) are converting solar energy into chemical energy via photosynthesis. A food chain can also depict a reduction in energy at each feeding level if the arrows, drawn between the different levels, continue to be reduced in size. Pyramids are graphical models of the quantitative differences that exist between the trophic levels of a single ecosystem. A pyramid of biomass represents the standing stock of each trophic level measured in units such as grams of biomass per square metre (g m–2). Biomass may also be measured in units of energy, such as J m –2. 2.2.U13 In accordance with the second law of thermodynamics, there is a tendency for numbers and quantities of biomass and energy to decrease along food chains; therefore, the pyramids become narrower towards the apex
Energy is lost as it is transferred between trophic levels; the efficiency of this energy transfer is measured by net production efficiency and trophic level transfer efficiency. Only 10% of the energy is transferred to the next, so the trophic efficiency=10%.Endotherms have a low NPE and use more energy for heat and respiration than ectotherms, so most endotherms have to eat more often than ectotherms to get the energy they need for survival. Energy transfers within food webs are determined by the first and second laws of thermodynamics..The second law relates to the quality of energy. This law states that whenever energy is transformed, some of the energy will lost to a less useful form. In ecosystems, the biggest losses occur as respiration. The second law explains why energy transfers are never 100% efficient. In fact, ecological efficiency, which is the amount of energy transferred from one trophic level to the next, ranges from 5-30%. On average, ecological efficiency is only about 10%. Because ecological efficiency is so low, each trophic level has a successively smaller energy pool from which it can withdraw energy. This is why food webs have no more than four to five trophic levels. Beyond that, there is not enough energy to sustain higher-order predators
image from goose.ycp.edu 2.2.U14 Bioaccumulation is the build-up of persistent or non-biodegradable pollutants within an organism or trophic level because they cannot be broken down
Include concentration of non‑biodegradable toxins in food chains, limited length of food chains, and vulnerability of top carnivores. Consider the terms biomagnification, bioaccumulation and bioconcentration.
2.2.U15 Biomagnification is the increase in concentration of persistent or non-biodegradable pollutants along a food chain
2.2.U16 Toxins such as DDT and mercury accumulate along food chains due to the decrease of biomass and energy
In the environment, insects would encounter DDT and absorb some of it into their bodies. Often, they would receive a sub-lethal dose, enough to impair them but perhaps not kill them. In any event, it stands to reason that insects either dying or merely slowed down by pesticide intake would become easy targets for birds. Upon ingestion, the DDT in the insect bodies is released and makes its way into the tissues of the bird's body, particularly the fat deposits. Because an individual bird eats many insects, and because the DDT does not leave the bird's body, and because DDT resists breaking down (either in the environment or the body), it accumulates to higher levels in the bird's tissues. In other words, the DDT that was spread out over, say 1,000 crickets will be concentrated in one bird. 2.2.U17 Pyramids of numbers can sometimes display different patterns; for example, when individuals at lower trophic levels are relatively large (inverted pyramids)]
Pyramid of numbers: Advantage
2.2.U18 A pyramid of biomass represents the standing stock or storage of each trophic level, measured in units such as grams of biomass per square metre (g m-2) or Joules per square metre (J m-2)(units of biomass or energy)
Pyramid of biomass: Contains the biomass at each trophic level. A pyramid of biomass represents the standing stock or storage of each trophic level, measured in units such as grams of biomass per square metre (g m–2). Pyramids of biomass can show greater quantities at higher trophic levels because they represent the biomass present at a fixed point in time, although seasonal variations may be marked. Advantage
2.2.U19 Pyramids of biomass can show greater quantities at higher trophic levels because they represent the biomass present at a fixed point in time, although seasonal variations may be marked. Pyramid of biomass is a diagram representing the amount of biomass measured in grams of dry mass per square metre (g m−2), found in a particular habitat at ascending trophic levels of a food chain. Biomass decreases at each ascending level of the food chain. A pyramid of biomass is a more accurate representation of the flow of energy through a food chain than a pyramid of numbers, but seasonal variations in the rate of turnover of the organisms at a particular level may result in higher or lower values for the amount of biomass sampled at a particular time than the average amount over the whole year. 2.2.U20 Pyramids of productivity refer to the flow of energy through a trophic level, indicating the rate at which that stock/storage is being generated
Pyramid of productivity: Pyramids of productivity refer to the flow of energy through a trophic level,indicating the rate at which that stock/storage is being generated. It contains the flow of energy through each trophic level; shows the energy being generated and available as food to the next trophic level during a fixed period of time, measured in units such as flow of biomass or energy per square metre (g m-2 yr-1) or Joules per square metre (J m-2 yr) (units of biomass or energy). Advantage
2.2.U21 Pyramids of productivity for entire ecosystems over a year always show a decrease along the food chain. Energy flows through the food chain in a predictable way, entering at the base of the food chain, by photosynthesis in primary producers, and then moving up the food chain to higher trophic levels . Because the transfer of energy from one trophic level to the next is inefficient, there is less energy entering higher trophic levels. Thus, diagrams showing how much energy enters each trophic level will have a distinct pyramid shape. In accordance with the second law of thermodynamics, there is a tendency for numbers and quantities of biomass and energy to decrease along food chains; therefore the pyramids become narrower as one ascends.Application and Skill 2.2.A1 Explain the transfer and transformation of energy as it flows through an ecosystem. Almost all energy enters Earth's ecosystems as solar insolation. That energy is then transformed and used by the diverse variety of organisms that make up food webs. Through photosynthesis, producers transform sunlight into glucose, which they then use for respiration. Chloroplasts in plant cells use sunlight to convert CO2 and water to glucose and oxygen gas. The plants' mitochondria then use the sugars for energy to drive respiration, their cellular processes required to stay alive.Explain pathways of incoming solar radiation incident on the ecosystem including:
2.2.A2 Analyse the efficiency of energy transfers through a system. Gross primary production is a measure of the energy that a plants transform from the sun. The fraction of that energy that is converted into glucose reflects the gross productivity of the plant. The energy remaining after respiration is considered the net primary production. In general, gross production refers to the energy contained within an organism before respiration and net production the energy after respiration. The terms can be used to describe energy transfer in both autotrophs and heterotrophs. Energy will decrease with each increase in trophic level- second law of thermodynamics states that during any transfer of energy, some is lost due to the tendency toward an increase in disorder (entropy). Energy for higher trophic levels is also constrained by loss due to metabolic respiration, as well as defensive strategies in some organisms that lowers the quality of food Energy transfer between trophic levels is generally inefficient, such that net production at one trophic level is generally only 10% of the net production at the preceding trophic level
2.2.A3 Explain the relevance of the laws of thermodynamics to the flow of energy through ecosystems Two laws of physics are important in the study of energy flow through ecosystems. The first law of thermodynamics states that energy cannot be created or destroyed; it can only be changed from one form to another. Energy for the functioning of an ecosystem comes from the Sun. Solar energy is absorbed by plants where in it is converted to stored chemical energy. The second law of thermodynamics states that whenever energy is transformed, there is a loss energy through the release of heat. This occurs when energy is transferred between trophic levels as illustrated in a food web. When one animal feeds off another, there is a loss of heat (energy) in the process. Additional loss of energy occurs during respiration and movement. Hence, more and more energy is lost as one moves up through trophic levels. 2.2.A4 Explain the impact of a persistent or non-biodegradable pollutant in an ecosystem. This refers to how long a pesticide remains active in the environment. Some chemicals are broken down by decomposers in the soil (they’re biodegradable) and so are not persistent, while others cannot be broken down by microbes (they’re non biodegradable) and so continue to act for many years, and are classed as persistent pesticides. The early pesticides (such DTT) were persistent and did a great deal of damage to the environment, and these have now largely been replaced with biodegradable insecticides such as carbamates and pyrethroid
image from InTech 2.2.S1 Construct models of feeding relationships such as food chains, food webs and ecological pyramids from given data
Systems diagrams can be used to show the flow of energy through ecosystems. Stores of energy are usually shown as boxes which represent the various trophic levels Flows of energy are usually shown as arrows (with the amount of energy in joules or biomass per unit are represented by the thickness of the arrow). 2.2.S2 Construct system diagrams representing photosynthesis and respiration.
Key Terms
Powerpoint and Notes Adapted from Brad Kremer, P Brooks and Ms. McCrindle Correct use of terminology is a key skill in ESS. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary. TOK
International-mindedness:
Video Clips Ecosystems, Organisms and Their Environment In which Hank does some push ups for science and describes the "economy" of cellular respiration and the various processes whereby our bodies create energy in the form of ATP. However, get hte basic idea. You won't need to know the specific details Hank explains the extremely complex series of reactions whereby plants feed themselves on sunlight, carbon dioxide and water, and also create some by products we're pretty fond of as well. However, get the basic idea. You won't need to know the specific details The grassland ecosystem and the food chain. Hank brings us to the next level of ecological study with ecosystem ecology, which looks at how energy, nutrients, and materials are getting shuffled around within an ecosystem (a collection of living and nonliving things interacting in a specific place), and which basically comes down to who is eating who. Interactions between species are what define ecological communities, and community ecology studies these interactions anywhere they take place. Although interspecies interactions are mostly competitive, competition is pretty dangerous, so a lot of interactions are actually about side-stepping direct competition and instead finding ways to divvy up resources to let species get along. Feel the love? Learn all about ecological pyramids and how to show quantitative data about relationships between species. Explaining the 10 percent rule in an ecosystem. Roughly 90 percent of energy is lost as it is transferred up each trophic levels. Explore biomagnification which can happen when toxins become more highly concentrated when moving up through trophic levels in the food chain. Uncontrolled use of DDT is used in video as an example. Learn why bioaccumulation can occur in high level consumers! New York State routinely produces health advisories for fish caught in local waters. These advisories are based on the potential for harmful substances- that is, pollutants- to be present in the flesh of the fish, which can be transferred to humans through consumption. A short clip about industrial mercury poisoning at Minamata Bay, Japan There are various species in the wild that were declining. One in particular, the bald eagle. |
What is a re created ecosystem in a laboratory environment known as?
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