Aiou solved assignments code 1421 autumn 2018. solved assignment 1 & 2 introduction to environment 2019 code 1421. past & old papers, assignments marks are aslo given.
AIOU BA Solved Assignment Code 1421
SUBJECT: Introduction to Environment CODE 1421
SEMESTER: Autumn, 2018 ASSIGNMENT No. 01
Q. 1 Differentiate between the following terms. (20)
i) Biocentric and Ecocentric
Public concern for the environment became widespread during the 1960s, after Rachel Carson wrote “Silent Spring.” Since that time, several different schools of thought have emerged with regard to the environment and the role people should play within the natural world. Biocentric and ecocentric philosophies are just two of the many different theories used to discuss nature. Although the philosophies are quite similar, they vary in some significant ways.
The Ecocentric Philosophy
People who ascribe to an ecocentric philosophy believe in the importance of an ecosystem as a whole. They attribute equal importance to living and non-living components of ecosystems when making decisions regarding their treatment of the environment. It is a holistic school of thought that sees little importance in individuals; ecocentrists are concerned or*zith how individuals influence ecosystems as a whole.
The Biocentric Philosophy
In contrast, a biocentric philosophy places the greatest importance on living individuals or living components of the environment. Biocentric theories do not consider chemical and geological elements of the envir nment to be as implortant as living beings in the way that ecocentric theories do. Biocentrists believe that all living things are important.example, a tree’s life would be
ii)Environmental Degradation and Environmental-eonservp *km
we. It consistslrf various aspeTts 1 e physical, biological, social, cultural etc.
onment like the construction of building, houses, bridges, industries etc. These
ronment l y.change or disturb their condition. The different aspects of the to vari s atural disasters like earthquake, volcano etc. This is also known as ation not be defined as the deterioration of the environment due to depletion of bpi; of e ecosystem and the eradication of wildlife.
considered just as important as a human’s life. This is in co ast to an nth entric view in Arrifich the lives of humans aregiven the greatest value.
The environment is the surrounding in which Human beings perform all the activities on activities affect the various aspects of environment are also changed or dis environmental degradation. Environniental degr resources such as air, water, and soil , the des
The United Nations International Strategy fgdisaster Reduction defines environmental degradation as “The reduction of the capacity of the environment to meet social and ecological objectives and needs”. There are various types of environmental degradation. When the various aspects of the environment are destroyed or damaged due to human activities or natural disaster, the environment is degraded. There are various causes of environmental degradation like pollution, overpopulation, deforestation, flood, landslide, earthquake etc.
Aiou Solved Assignments Code 1421 Autumn 2018
If the environmental degradation is caused due to the natural disaster like volcano, earthquake, etc. then it is called natural cause. As the population of the world is increasing day by day, the natural resources are being excessively used to fulfill the needs and demands. Various human activities li0 construction of buildings, industries, bridges, using of chemical fertilizers, pollution, cutting down of trees, etc caused d tion of the environment. In this note, we study about the major human activities that cause
iii) Mineral and Non-Minerals
Every person uses products made from minerals every day. The salt that we add to our food is the mineral halite. Antacid tablets are made from the mineral calcite.
It takes many minerals to make something as simple as a wooden pencil. The “lead” is made from graphite and clay minerals, the brass band is made of copper and zinc, and the paint that colors it contains pigments and fillers made from a variety of minerals. A cell phone is made using dozens of different minerals that are sourced from mines throughout the world.
The cars that we drive, the roads that we travel, the buildings that we live in, and the fertilizers used to produce our food are all made using minerals. In the United States, about three trillion tons of mineral commodities are consumed each year to support the standard of living of 300 million citizens. That is about ten tons of mineral materials consumed for every person, every year.
Physical Properties of Minerals
There are approximately 4000 different minerals, and each of those minerals has a unique set of physical properties. These include: color, streak, hardness, luster, diaphaneity, specific gravity, cleavage, fracture, magnetism, solubility, and many more. These physical properties are useful for identifying minerals. However, they are much more important in determining the potential industrial uses of the mineral. Let’s consider a few examples.
The mineral talc, when ground into a powder, is perfectly suited for use as a foot powder. It is a soft, slippery powder so it will not cause abrasion. It has the ability to absorb moisture, oils, and odor. It adheres to the skin and produces an astringent effect – yet it washes off easily. No other mineral has a set of physical properties that are as suitable for this purpose.
The mineral halite, when crushed into small grains, is perfectly suited for flavoring food. It has a salty taste that most people find pleasing. It dissolves quickly and easily, allowing its flavor to spread through the food. It is soft, so if some does not dissolve it will not damage your teeth. No other mineral has physical properties that are better suited for this use.
Heterotrophs and Autotrophs
Ozone and Smog.
AIOU Solved Assignments BA Code 1421
Q. 2 It is essential to make the public aware of the alarming cees of the environmente adation. Briefly discuss some of the environmental challenges that we face today at 1111 onal as well as the global Dere .
The sum total of all surroundings of a living organism, including natural forces and other living things, which provide conditions for development and growth as well as of danger and damage. The field defines the term environment very broadly including all that is natural on the planet as well as social settings, built environments, learning environments and informational environments. When solving problems involving human-environment interactions, whether global or local, one must have a model of human nature that predicts the environmental conditions under which humans will behave in a decent and creative manner. With such a model one can design, manage, protect and/or restore environments that enhance reasonable behavior, predict what the likely outcome will be when these conditions are not met, and diagnose problem situations.
Scope of environmental science:
Environment is nothing but the nature composed of both biotic and abiotic factors. It has profound effect over the living organisms. It also exerts influence over their metabolic activities. It causes even evolution to occur as the environment is dynamic and ever changing. Its scope is so wide that it has got relation with every science and scientific aspects in general and biology in particular. Its study makes the man to understand its importance. He would be able to take necessary steps to protect it though nature can take care of the human beings. Environmental Science will be a growing field for the future with the growing concerns about our global warming and climate changes. Other fields such as ecology, botany, and meteorology besides all other major branches of the science, arts and commerce.
Major aspect and importance:
is concerned with the day today interaction with the surroundings with which human being is closely associated.
is related to many branches of the science and is an interdisciplinary problems.
is concerned with the importance of wild life its protection
explains the significant role of biodiversity in establishing ecological balance
deals with different types of ecosystems, biotic and abiotic factors and their role in the significance and sustenance of ecosystems.
is concerned with different types of food chains, food webs, productivity, biomass, carrying capacity of ecosystems.
deals with various types of interrelationships existing between living and non living organisms and also between different types of living organisms such as symbiosis, mutualism, commensalism, parasitism, competition, antibiosis etc.,
gives information relating to population explosion, growth and development, impact of population growth on the resource consumption and national economy.
Explains the coexistence of both living and non living organisms and their contribution to the nature for its sustenance.
Deals with relation with ethos and the impact of ethical principles in the conservation of wild life, biodiversity and environment.
Explains the significance of forests and their products in the human routine and in country’s economy.
➢ Gives information about water conservation, watershed management and the importance of water as a universal solvent
and the importance of the same in various physiological, biochemical, internal systems and external environment.
Consequences of the Environmental Degradation
The world faces a broad range of environmental problems, including pollution, habitat destruction, loss of biodiversity, scarcity of water, overfishing, agricultural land degradation, over-exploitation of natural resources and overproduction of greenhouse gases leading to climate change. The list of consequences is even longer. Environmental degradation by its essential nature results in a planet less suited to supporting life. Environmental problems endanger public health and have undesirable long-term economic consequences. In their worst manifestations, unaddressed environmental problems can render large areas of the planet unsuitable for human habitation.
Loss of Biodiversity
A global loss of biodiversity has accelerated since the age of industrialization, approaching 1,000 times the normal rate for extinctions on the planet. The acceleration of extinctions is almost certain to continue, due primarily to habitat loss, pollution, over-harvesting, and the introduction of invasive species. Biodiversity provides innumerable services to humanity, including air and water quality, pollination, and agricultural productivity, Currently between 10 and 30 percent of land animals are threatened with extinction, and 75 percent of fisheries are over-exploited. Loss of biodiversity, and the complex ecological systems it supports, is irretrievable. The human population sits at the pinnacle of a food and sustenance chain that is breaking at ever faster rates of speed.•
Economic Impacts of Environmental Degradation*
The world economy rests on the back of the environment. Over-harvesting of natural resources leads to scarcity. Pollution of air and water leads to deteriorating public health and requires additional expenditures to treat it. Pollution also renders land and water unsuitable for economic activity, whether agriculture, fisheries or tourism. Environmental degradation by definition means a loss of common resources, including forests, rivers and streams, topsoil and local biodiversity. When common resources are lost due to over-exploitation or pollution, human communities lose the future opportunity for economic use.
According to the World Health Organization, one-quarter of global disease, and one-third of childhood disease, is a result of environmental hazards. Environmental toxins caused by pollution are a major culprit. Water-born illnesses such as diarrhea afflict millions in developing countries, and are compounded by problems of food scarcity. Approximately one in eight people lacks access to safe water. Air pollution causes respiratory illness. Pollution also leads to increased rates of cancer throughout the developing and developed world.
Environmental catastrophes catastrophes often occur due to neglect, whether through lack of adequate regulation and enforcement, or through willful violation of environmental standards. The BP Gulf oil spill was only the latest of many such catastrophes. The Chernobyl nuclear accident caused widespread human health problems and the evacuation of a large area in Ukraine. The Bhopal chemical disaster in India killed over 3500 people. Other environmental disasters include the pollution of the Niger delta in Nigeria, the Fukushima nuclear following the 2011 earthquake and tsunami and the environmental threat to the Great Barrier Reef in Australia.
Scope of environment science in istan
Department of Environmental ‘ences has been established very recently in June 2010 keeping in view the pivotal importance of this subject in Pakistan . This subject as gathered a high reputation all around the world due its applied nature. Environmental science is a cosmopolitan subject because it deals with various branches of studies like chemistry, physics, botany, zoology, geology, geography, and public health etc. It focuses on the sources, reactions, transport, effects and fate of physical and biological species in the air, water and soil along with the effects of human activity upon these. Air, water, land, and noise pollution constantly imperil quality of life and damage the pristine environment. World today is facing serious environmental crisis, for instance, increase in the heat budget of the earth, depletion of non-renewable resources, air pollution, pollution of surface & ground waters, heavy metal pollution, massive destruction of habitats, deforestation, mining, over-fishing and radiation pollution. E cosystem of earth is very fragile, and that man’s tampering with it may, in the end, make the earth unlivable, not only for man but for all life forms. Hence, study in the subject of Environmental Science builds skill and knowledge to play an active role in the society.
Environmental awareness among society and especially in students will be of utmost important as they are future leaders, future custodians, planners, policy makers, and educators of the environmental issues. Students will undertake basic and applied research on different environmental issues, and will assist government departments, private sector, and other relevant organizations on the framing of rules & regulations along with establishment of appropriate institutions and systems etc. Following are the key objectives of Department of Environmental Sciences:
To produce enthusiastic, skilled and motivated environmentalists
Addressing environmental issues and hazardous wastes/effluents
Solid waste management/recycling technologies
Causes and control of air, water and land pollution
Integrated pest management/biological control of diseases
Improving & conserving biodiversity and supporting forestry
Fumigation studies for screening native crops and fruits
Environmental impact assessment studies
Preservation of cultural heritage from pollutants
Imparting applied environmental education to society.
AIOU Solved Assignments Introduction to Environment Code 1421
Q. 3 Define Ecosystem. What are the essential components of an ecosystem? Give suitable examples. (16)
The ecosystem is a core concept in Biology and Ecology, serving as the level of biological organization in which organisms interact simultaneously with each other and with their environment. As such, ecosystems are a level above that of the ecological community (organisms of different species interacting with each other) but are at a level below, or equal to, biomes and the biosphere. Essentially, biomes are regional ecosystems, and the biosphere is the largest of all possible ecosystems. jr
Ecosystems include living organisms, the dead organic matter produced by them, the abiotic environment within which the organisms live and exchange elements (soils, water, atmosphere), and the interactions between these components. Ecosystems embody the concept that living organisms continually interact with each other and with the environment to produce complex systems with emergent properties, such that “the whole is greater than the sum of its parts” and “everything is connected”.
Component organisms and the matter:
The spatial boundaries, component organisms and the matter and energy content and flux within ecosystems may be defined and measured. However, unlike organisms or energy, ecosystems are inherently conceptual, in that different observers may legitimately define their boundaries and components differently. For example, a single patch of trees together with the soil, organisms and atmosphere interacting with them may define a forest ecosystem, yet the entirety of all organisms, their environment, and their interactions across an entire forested might also be defined as a single forest ecosystem. Some have even called the interacting system of organisms that live within the guts of most animals as an ecosystem, despite their residence within a single organism, which violates the levels of organization definition of ecosystems. Moreover, interactions between ecosystem components are as much a part of the definition of ecosystems as their constituent organisms, matter and energy. Despite the apparent contradictions that result from the flexibility of the ecosystem concept, it is just this flexibility that has made it such a useful an d enduring concept.
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Human alteration of ecosystems:
Ecosystem science is evolving rapidly in both methodology and focus. Human alteration of ecosystems is now so pervasive globally that ecologists are working to integrate humans into ecosystem science at many levels—including the study of urban ecology, agroecology and global ecology. New techniques for ecosystem modeling are being developed all the time, as are new methods for observing ecosystems from space by remote sensing and aerial platforms, and even by networks of sensors embedded in soils and plants across ecosystems and on towers that can make observations on ecosystem exchanges with the atmosphere on a continuous basis. Examples of cutting edge ecosystem research are the Carnegie Airborne Observatory—an aerial remote sensing system capably of precisely mapping ecosystem carbon and species diversity, and the development of the research platform for discovering and understanding the impacts of climate change, land-use change, and invasive species on ecosystems.
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A terrestrial ecosystem is an ecosystem found only on a landform. Four primary terrestrial ecosystems exist: tundra, taiga, temperate deciduous forest, and grassland A community of organisms and their environment that occurs on the land masses of continents and islands. Terrestrial ecosystems are distinguished from aquatic ecosystems by the lower availability of water and the consequent importance of water as a limiting factor. Terrestrial ecosystems are characterized by greater temperature fluctuations on both a diurnal and seasonal basis than occur in aquatic ecosystems in similar climates. The availability of light is greater in terrestrial ecosystems than in aquatic ecosystems because the atmosphere is more transparent than water. Gases are more available in terrestrial ecosystems than in aquatic ecosystems. Those gases include carbon dioxide that serves as a substrate for
photosynthesis, oxygen that serves as a substrate in aerobic respiration, and nitrogen that serves as a substrate for nitrogen fixation.
An ecosystem does not exist in isolation. Its existence is dependent upon the components within it and its relationship with external elements. Since the Industrial Revolution, the Earth has experienced great change, much of it at the hands of humans. Humans have increased the extinction rate of the world’s plants and animals by 10,000 percent. As awareness of this impact has increased, however, so have the positive influences that humans have had on ecosystems.
An ecosystem benefits from humans through environmental management, which aims to restore balance and minimize disturbances within an ecosystem.
With the creation of the National Park Service, National Wildlife Refuge System, and state-managed wilderness areas, unique ecosystems have been preserved so that future generations may experience the grandeur of the American landscape, despite environmental pressures such as increased tourist traffic.
Humans help ecosystems by assuming the role of predators such as wolves, which were nearly eradicated early in the 20th century, and help prevent prey species such as deer from depleting food resourc-_:
Through clean air, clean water, and other regulatory measures, humans have reduced the amount of pollution they create, allowing ecosystems to recover from past impacts such as acid rain.
According to a Harris Interactive Poll, over two-thirds of Americ recycle, which uses 90 percent less energy, thereby reducing
their environmental impact and benefiting the ecosystem.
AIOU Solved Assignments Introduction to Environment
Q. 4 Define green house effect. Briefl ccuss th ouse gass. ow do these contribute to increase the
temperature of the earth? (16)
According to NASA, the earth’s atmosphere is divided into four major sections or “spheres.” The lower atmosphere is known as the troposphere and extends up to nine miles into the air. All of the air that directly supports life on earth is found in the troposphere. All weather activity also occurs in this layer, which primarily consists of nitrogen and oxygen.
The lower atmosphere is approximately 78 percent nitrogen. The primary purpose of atmospheric nitrogen is to dilute the oxygen in the air. Nitrogen is not combustible, but oxygen is. The presence of nitrogen helps stabilize this combustibility. Nitrogen is odorless, tasteless and colorless. It is not poisonous, but it cannot sustain life on its own. Atmospheric nitrogen cannot be processed directly by plants and animals. It is pulled from the atmosphere by a specific type of bacteria, which then deposits it in the soil where it becomes a vital mineral in plant growth.
The lower atmosphere is roughly 21 percent oxygen. Oxygen is the essential element that sustains life on earth. Plants produce oxygen through photosynthesis, a process that uses sunlight to convert water and carbon dioxide into glucose. Animals breathe in this oxygen, which, among other things, allows the body to process food for energy.
One of the most physically obvious components of the earth’s lower atmosphere is water vapor. Depending on its intensity, water vapor can comprise up to 4 percent of the atmosphere. Water vapor causes the air to feel “muggy” on humid days. It also is visible in the form of fog and clouds. The condensation of water vapor in the air causes precipitation, which is also vital to live on earth.
The remaining percentage of the atmosphere is made up of argon, carbon dioxide, neon, helium, methane, hydrogen, nitrous oxide
and ozone. The most common of these gases is argon, which makes up 0.93 percent of the lower atmosphere. The least common is
ozone, which occupies only four parts per million in the lower atmosphere or 0.000004 percent. The majority of ozone in the earth’s atmosphere is found above the lower atmosphere in the stratosphere.
Composition and Layers of the Atmosphere
The atmosphere surrounding the Earth is made up of many gases, the most prevalent of which are nitrogen and oxygen. It also contains water vapor, dust and ozone. The lowest layer of the atmosphere is the troposphere. The higher up you go in the troposphere, the lower the temperature. Above the troposphere is the stratosphere, the area where planes fly. The temperature increases as you move up through this layer because of ozone, which absorbs solar radiation. Above the stratosphere is the mesosphere; here, the temperature decreases. Above the stratosphere is the thermosphere, where it is hot and the air is thin. Finally, there is the exosphere, where satellites orbit.
Ozone is concentrated mainly in the stratosphere, where it absorbs solar radiation, protecting Earth’s living organisms from the ultraviolet light from the sun. UV radiation is harmful; without the atmosphere’s ozone, living organisms could not exist on Earth. UV light causes cancer and cataracts, and it damages DNA. In recent years, the ozone layer has decreased, a cause for concern.
The greenhouse effect refers to the ability of some components of the atmosphere–primarily carbon dioxide–to absorb and trap heat. While too much heat is a problem–consequences being a change in weather and climate, and a rise in sea levels–the greenhouse effect is a necessary protector of life on Earth. It lets the atmosphere function like a blanket, allowing for temperatures hospitable to the planet’s life. People exhale carbon dioxide and release it into the atmosphere when burning fossil fuels and plants. Plants absorb carbon dioxide as part of photosynthesis, keeping the carbon and releasing oxygen. The moon, which has no atmosphere, has an average temperature of 0 degrees Fahrenheit (-18 degrees Celsius).
Mitigating Risk from Meteorite Impact
There are a lot of rocks and dust moving about the solar system, some of them quite large. These bodies are called meteoroids. When these meteoroids hit the Earth, sometimes causing damage, they’re called meteorites. Luckily, the atmosphere protects the Earth from meteorite impact. Almost all meteoroids crash into the atmosphere at extremely high speeds, disintegrating and creating a glow that can be seen as a streak in the sky. These bodies arc called meteors.
Preventing Rapid Burning
Because of the atmosphere’s proportion of gases, the Eartn’s surface and its living creatures are protected from rapid combustion–burning. Burning requires oxygen, which is the second most prevalent gas in the atmosphere, making up almost 21 percent of its composition in the form of Nitrogen, luckily, is the most prevalent gas, making up over 78 percent of the atmosphere in the form of The nitrogen dilutes the oxygen, and Earth’s surface avoids the negative consequences of oxygen’s usefulness as a component of fire. (Oxygen itself is not combustible, but it reacts with other things to produce fire.)
Solved Assignments Introduction to Environment Code 1421
Q. 5 Write a not on composition and structure of Lithosphere. Explain with the help of a suitable diagram. (16)
Core, mantle, and crust are divisions based on composition. The crust makes up less than 1 percent of Earth by mass, consisting of oceanic crust and continental crust is often more felsic rock. The mantle is hot and represents about 68 percent of Earth’s mass. Finally, the core is mostly iron metal. The core makes up about 31% of the Earth. Lithosphere and asthenosphere are divisions based on mechanical properties. The lithosphere is composed of both the crust and the portion of the upper mantle that behaves as a brittle, rigid solid. The asthenospliere is partially molten upper mantle material that behaves plastically and can flow. This animation by Earthquide shows tl Dyers by composition and by mechanical properties.
Crust and Lithosphere
Earth’s outer surface is its crust; a cold, thin, brittle outer shell made of rock. The crust is very thin, relative to the radius of the planet. There are two very different types of crust, each with its own distinctive physical and chemical properties.Oceanic crust is composed of magma that erupts on the seafloor to create basalt lava flows or cools deeper down to create the intrusive igneous rock gabbro. Sediments, primarily muds and the shells of tiny sea creatures, coat the seafloor. Sediment is thickest near the shore where it comes off the continents in rivers and on wind currents.Continental crust is made up of many different types of igneous, metamorphic, and sedimentary rocks. The average composition is granite, which is much less dense than the mafic igneous rocks of the oceanic crust. Because it is thick and has relatively low density, continental crust rises higher on the mantle than oceanic crust, which sinks into the mantle to form basins. When filled with water, these basins form the planet’s oceans.The lithosphere is
the outermost mechanical layer, which behaves as a brittle, rigid solid. The lithosphere is about 100 kilometers thick. The definition of the lithosphere is based on how earth materials behave, so it includes the crust and the uppermost mantle, which are both brittle. Since it is rigid and brittle, when stresses act on the lithosphere, it breaks. This is what we experience as an earthquake.
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The two most important things about the mantle are: (1) it is made of solid rock, and (2) it is hot. Scientists know that the mantle is made of rock based on evidence from seismic waves, heat flow, and meteorites. The properties fit the ultramafic rock peridotite, which is made of the iron- and magnesium-rich silicate minerals. Peridotite is rarely found at Earth’s surface.Scientists know that the mantle is extremely hot because of the heat flowing outward from it and because of its physical properties. Heat flows in two different ways within the Earth: conduction and convection. Conduction is defined as the heat transfer that occurs through rapid collisions of atoms, which can only happen if the material is solid. Heat flows from warmer to cooler places until all are the same temperature. The mantle is hot mostly because of heat conducted from the core. Convection is the process of a material that can move and flow may develop convection currents.Convection in the mantle is the same as convection in a pot of water on a stove. Convection currents within Earth’s mantle form as material near the core heats up. As the core heats the bottom layer of mantle material, particles move more rapidly, decreasing its density and causing it to rise. The rising material begins the convection current. When the warm material reaches the surface, it spreads horizontally. The material cools because it is no longer near the core. It eventually becomes cool and dense enough to sink back down into the mantle. At the bottom of the mantle, the material travels horizontally and is heated by the core. It reaches the location where warm mantle material rises, and the mantle convection cell is complete.
Convection in the mantle is the same as convection in a pot of water on a stove. Convection currents within Earth’s mantle form as material near the core heats up. As the core heats the bottom layer of mantle material, particles move more rapidly, decreasing its density and causing it to rise. The rising material begins the convection current. When the warm material reaches the surface, it spreads horizontally. The material cools because it is no longer near the core. It eventually becomes cool and dense enough to sink back down into the mantle. At the bottom of the mantle, the material travels horizontally and is heated by the core. It reaches the location where warm mantle material rises, and the mantle convection cell is complete.
Solved Assignments Introduction to Environment
Q. 6 Write notes and draw suitable diagram. (16)
i) Ecological Pyramid
An ecological pyramid is a graphical representation of the relationship between different organisms in an ecosystem. Each of the bars that make up the pyramid represents a different trophic level, and their order, which is based on who eats whom, represents the flow of energy. Energy moves up the pyramid, starting with the primary producers, or autotrophs, such as plants and algae at the very bottom, followed by the primary consumers, which feed on these plants, then secondary consumers, which feed on the primary consumers, and so on. The height of the bars should all be the same, but the width of each bar is based on the quantity of the aspect being measured.
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Types of Ecological Pyramids Pyramid of numbers
This shows the number of organisms in each trophic level without any consideration for their size. This type of pyramid can be convenient, as counting is often a simple task and can be done over the years to observe the changes in a particular ecosystem. However, some types of organisms are difficult to count, especially when it comes to some juvenile forms. Unit: number of organisms.
Pyramid of biomass
This indicates the total mass of organisms at each trophic level. Usually, this type of pyramid is largest at the bottom and gets smaller going up, but exceptions do exist. The biomass of one trophic level is calculated by multiplying the number of individuals in the trophic level by the average mass of one individual in a particular area. This type of ecological pyramid solves some problems of the pyramid of numbers, as it shows a more accurate representation of the amount of energy contained in each trophic level, but it has its own limitations. For example, the time of year when the data are gathered is very important, since different species have different breeding seasons. Also, since it’s usually impossible to measure the mass of every single organism, only a sample is taken, possibly leading to inaccuracies. Unit: g m-2 or Kg m-2.
Pyramid of productivity
The pyramid of productivity looks at the total amount of energy present at each trophic level, as well as the loss of energy between trophic levels. Since this type of representation takes into account the fact that the majority of the energy present at one trophic level will not be available for the next one, it is more accurate than the other two pyramids. This idea is based on Lindeman’s Ten Percent Law, which states that only about 10% of the energy in a trophic level will go towards creating biomass. In other words, only about 10% of the energy will go into making tissue, such as stems, leaves, muscles, etc. in the next trophic level. The rest is used in respiration, hunting, and other activities, or is lost to the surroundings as heat. What’s interesting, however, is that toxins are passed up the pyramid very efficiently, which means that as we go up the ecological pyramid, the amount of harmful chemicals is more and more concentrated in the organisms’ bodies. This is what we call biomagnification.
The pyramid of productivity is the most widely used type of ecological pyramid, and, unlike the two other types, can never be largest at the apex and smallest at the bottom. It’s an important type of ecological pyramid because it examines the flow of energy in an ecosystem over time. Unit: J m2 yr’, where Joule is the unit for energy, which can be interchanged by other units of energy such as Kilojoule, Kilocalorie, and calorie.
While a productivity pyramid always takes an upright pyramid shape, nurn er pyramids are sometimes inverted, or don’t take the shape of an actual pyramid at all. To demonstrate, let’s take an oak tree, which can feed millions of oakworms. If we consider this ecosystem as our focus, then the producers’ level (one tree) will end up much smaller than the primary consumers’ level (millions of insects). This is less likely to occur in biomass pyramids, but is not impossible. The pyramids below show the different types of pyramids and the shapes they can have in different ecosystems.
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Ecological Pyramid Examples
The diagram below is an example of a productivity pyramid, otherwise called an energy pyramid. The sun has been included in this diagram, as it’s the main source of all energy, as well the decomposers, like bacteria and fungi, which can acquire nutrients and energy from all trophic levels by breaking down dead or decaying organisms. As shown, the nutrients then go back into the soil and are taken up by plants.
The loss of energy to the surroundings is also shown in this diagram, and the total energy transfer has been calculated. We start off with the total amount of energy that the primary producers contain, which is indicated by 100%. As we go up one level, 90% of that energy is used in ways other than to create flesh. What the primary consumers end up with is just 10% of the starting energy, and, 10% of that 10% is lost in the transfer to the next level. That’s 1%, and so on. The predators at the apex, then, will only receive 0.01% of the starting energy! This inefficiency in the system is the reason why productivity pyramids are always upright.
Function of Ecological Pyramid
An ecological pyramid not only shows us the feeding patterns of organisms in different ecosystems, but can also give us an insight into how inefficient energy transfer is, and show the influence that a change in numbers at one trophic level can have on the trophic levels above and below it. Also, when data are collected over the years, the effects of the changes that take place in the environment on the organisms can be studied by comparing the data. If an ecosystem’s conditions are found to be worsening over the years because of pollution or overhunting by humans, action can be taken to prevent further damage and possibly reverse some of the present damage.
Related Biology Terms
Trophic level — The position that an organism occupies within a food chain or an ecological pyramid, such as a producer, or a primary consumer. Many animals feed at several different trophic levels.
Species — A group of organisms that exhibit common characteristics and can breed among themselves to produce fertile offspring. ■■./‘
Ecosystem — A commur:tv of interdependent living organisms in association with the nonliving elements surrounding them. The way the living organisms and the physical environment interact is by exchange of nutrients and energy.
Food web — A system of food chains that are interlocked with one another. Unlike in food chains, an organism in a food web can occupy several different trophic levels.
ii) Positive Interactions among Organisms
No man is an island.” This saying is also true for organisms in an ecosystem. No organism exists in isolation. Individual organisms live together in an ecosystem and depend on one another. In fact, they have many different types of interactions with each other, and many of these interactions are critical for their survival.
So what do these interactions look like in an ecosystem? One category of interactions describes the different ways organisms obtain their food and energy. Some organisms can make their own food, and other organisms have to get their food by eating other organisms. An organism that must obtain their nutrients by eating (consuming) other organisms is called a consumer, or a heterotroph. While there are a lot of fancy words related to the sciences, one of the great things is that many of them are based on Latin or Greek roots. For example, heterotroph becomes easier to remember when you realize that in Greek, “hetero” means “other” and “troph” means food; in other words, heterotrophs eat other organisms to get their food. They then use the energy and materials in that food to grow, reproduce and carry out all of their life activities. All animals, all fungi, and some kinds of bacteria are heterotrophs and consumers. .
Carnivores and herbivores
Some consumers are predators; they hunt, catch, kill, and eat other animals, the prey. The prey animal tries to avoid being eaten by hiding, fleeing, or defending itself using various adaptations and strategies. These could be the camouflage of an octopus or a fawn, the fast speed of a jackrabbit or impala, or the sting of a bee or spines of a sea urchin. If the prey is not successful, it becomes a meal and energy source for the predator. If the prey is successful and eludes its predator, the predator must expend precious energy to continue the hunt elsewhere. Predators can also be prey, depending on what part of the food chain you are
looking at. For example, a trout acts as a predator when it eats insects, but it is prey when it is eaten by a bear. It all depends on the specific details of the interaction. Ecologists use other specific names that describe what type of food a consumer eats: carnivores and herbivores are meat eaters and plant eaters, respectively. Omnivores eat both animals and plants. Once again, knowing the Latin root helps a lot: “vor” means “to eat or devour,” as in “voracious.” Put “-yore” at the end of a scientific term for a kind of food, and you have described what an organism eats. For example, an insectivore is a carnivore that eats insects, and a frugivore is an herbivore that eats fruit. This may seem like a lot of terminology, but it helps scientists communicate and immediately understand a lot about a particular type of organism by using the precise terms.
Not all organisms need to eat others for food and energy. Some organisms have the amazing ability to make (produce) their own energy-rich food molecules from sunlight and simple chemicals. Organisms that make their own food by using sunlight or chemical energy to convert simple inorganic molecules into complex, energy-rich organic molecules like glucose are called producers or autotrophs. And here’s another quick Greek lesson: “auto” means “self’ and “troph” still means “food.” So autotrophs are self-feeding; they make their own food. Plants, algae, and microscopic organisms such as phytoplankton and some bacteria, make energy-rich molecules (in other words, their food) from sunlight, water, and carbon dioxide during the process called photosynthesis (“photo” means “light, and “synthesis” means “to make” — photosynthesizers are using sunlight to make food). Some producers are chemosynthesizers (using chemicals to make food) rather than photosynthesizers; instead of using sunlight as the source of energy to make energy-rich molecules, these bacteria and their relatives use simple chemicals as their source of energy. Chemosynthesizers live in places with no sunlight, such as along oceanic vents at great depths on the ocean floor.
No matter how long you or a giraffe stands out in the sun, you will never be able to make food by just soaking up the sunshine; you will never be able to photosynthesize. You’ll just get sunburned and thirsty and will still need to go eat another organism if you are hungry. Producers use the food that they make and the chemical energy it contains to meet their own needs for building-block molecules and energy so that they can do things such as grow, move, and reproduce. When a consumer comes along and eats a producer, the consumer gets the building-block molecules and the chemical energy that is in the producer’s body. All other life depends on the energy-rich food molecules made by producers — either directly by eating producers, or indirectly by eating organisms that have eaten producers. Not surprisingly, ecologists also have terms that describe where in the food chain a particular consumer operates. A primary consumer eats producers (e.g., a caterpillar eating a leaf); a secondary consumer eats primary consumers (e.g., a robin eating the caterpillar). And it can go even further: a tertiary consumer eats secondary consumers (e.g., a hawk eating the robin). A single individual animal can act as a different type of consumer depending on what it is eating. When a bear eats berries, for example, it is being a primary consumer, but when it eats a fish, it might be a secondary or a tertiary consumer, depending on what the fish ate! Ni
All organisms play a part in the web of life and every living thing will die at some point. This is where scavengers, detritivores (which eat detritus or parts of dead things), and decomposers come in. They all play a critical role that often goes unnoticed when observing the workings of an ecosystem. They break down carcasses, body parts and waste products, returning to the ecosystem the nutrients and minerals stored in them. This interaction is critical for our health and health of the entire planet; without them we would be literally buried in dead stuff. Crabs, insects, fungi and bacteria are examples of these important clean-up specialists.
Another category of interactions between organisms has to do with close, usually long-term interaction between different types of organisms. These interactions are called symbiosis. The impacts of symbiosis can be positive, negative, or neutral for the individuals involved. Organisms often provide resources or services to each other; the interaction is mutually beneficial. These “win-win” symbiotic interactions are known as mutualism (+ +). For example, ants living in a tree may protect the tree from an organism that would like to make the tree its next meal, and at the same time the tree provides a safe home for the ants. Symbiotic relationships are not always positive for both participants. Sometimes there are definite losers. In parasitism (+ -), for example, the parasite benefits and the host is harmed, such as when a tick sucks blood out of a dog. Predation (+ -) is another winner-loser relationship but it is not symbiosis. The predator benefits and the prey is harmed lethally, but it is a short-term interaction. In parasitism, the parasite does not usually kill its host, but just feeds on it for a long time while it is living.
Other symbiotic interactions, called commensalism (+ 0), are beneficial for one organism, but do not affect the other in a positive or a negative way. The interaction is seemingly neutral for one of the organisms. For example, a barnacle attached to a whale is able to travel thousands of miles collecting and filtering food from the moving water. The whale doesn’t seem to be affected by the little hitchhikers. But then again, maybe those little hitchhikers are actually creating a tiny amount of additional drag as the whale moves through the water and therefore the whale has to expend just a little bit of additional energy. If so, that would be a negative impact for the whale. Often, further research reveals that what was originally thought to be neutral for one participant and therefore an example of commensalism, actually has a very subtle positive or negative impact, so the classification is no longer commensalism, but rather mutualism or parasitism. Is a bird nest on a tree limb commensalism, or is there some slight advantage or disadvantage for the tree in having the nest there? It is possible to come up with plausible explanations either way; only detailed research could provide the necessary information to answer the question. 4!)
Competition is an interesting example of interactions. When two organisms compete or fight for the same limited resource such as food, shelter, a mate, or sunlight, there is usually a winner and a loser (+ -), but if the competitors fight literally to the death and kill each other, the interaction has become negative for both (- -). Competition is also an interesting example because it is just as likely to be intraspecific as interspecific (language alert: the prefix “intra” means “within” and the prefix “inter” means “between”). An intraspecific interaction occurs within a species (e.g., two bull elephant seals competing for a harem of females or two English ivy plants competing for space and sunlight), and an interspecific interaction occurs between members of different species (e.g., when two different species of corals compete for space and sunlight on a coral reef by trying to outgrow each other). If the competition is long-term and occurs between two different species, it would be another example of symbiosis.
In summary, there are many different kinds of interactions between organisms in an ecosystem and it is not unusual for any particular organism to wear many hats and play multiple roles at different times. For example, we humans are consumers and predators when we hunt, kill, and eat other animals such as a fish or a deer, or when we eat chicken we have purchased at the grocery store or a restaurant. We also have many mutualistic relationships with other organisms, such as our pets. Competition
also occurs between humans for resources, even mates! Interactions between organisms, including humans, are the nature of life and have tremendous impact on the functioning and health of ecosystems.