{"id":488,"date":"2017-08-17T07:38:22","date_gmt":"2017-08-17T07:38:22","guid":{"rendered":"http:\/\/americanboard.org\/Subjects\/biology\/?page_id=488"},"modified":"2017-08-17T09:15:01","modified_gmt":"2017-08-17T09:15:01","slug":"ecosystems","status":"publish","type":"page","link":"https:\/\/americanboard.org\/Subjects\/biology\/ecosystems\/","title":{"rendered":"Ecosystems"},"content":{"rendered":"<div class=\"twelve columns\" style=\"margin-top: 10%;\">\n<div class=\"advance\"><a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/biology\/human-body-systems\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/biology\/basic-science-core\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/biology\/further-reading\">Further Reading \u27a1<\/a><\/div>\n<p><!-- CONTENT BEGINS HERE --><\/p>\n<h1 id=\"title\">Ecosystems<\/h1>\n<h4>Objective<\/h4>\n<p>In this lesson, you will review the components of ecosystems. Scientists, regardless of their specialization, need to possess a basic level of science literacy across all disciplines. This lesson provides an overview of the major concepts pertaining to ecosystems that all students of the sciences should know. The chapters that follow will focus in greater detail on these ideas.<\/p>\n<h4>Previously Covered:<\/h4>\n<ul>\n<li>Living systems are complex and function via constant flows of energy and cycling of nutrients<\/li>\n<\/ul>\n<section>\n<h3>Systems Analyses<\/h3>\n<p><abbr title=\"an ecological unit made up of the organisms and environmental characteristics that support it\">Ecosystems<\/abbr> are organized, just as cells and organisms are organized. Individual organisms are members of <abbr title=\"a group of organisms of the same species living in the same area\">populations<\/abbr>. A population is a group of organisms of the same species living in the same area. Multiple populations of different species make up a <abbr title=\"a geographic area that supports diverse species populations\">community<\/abbr> within that area. A community of living things and the <abbr title=\"non-living elements of a habitat, such as wind, water, sunlight, temperature, rocks, soil and periodic disturbances, which are factors that have a direct affect on local species distribution\">abiotic<\/abbr> environment of those organisms constitutes an ecosystem. All of the living systems of the earth constitute the biosphere.<\/p>\n<p class=\"center\">organism \u2192 population \u2192 community \u2192 ecosystem \u2192 biosphere<\/p>\n<p>Just as in a cell or an organism, an ecosystem has constant flows of energy and cycling of materials. Those flows are generated by the <abbr title=\"the living body's chemical process for the transformation of energy in support of function and activity\">metabolism<\/abbr> of the organisms within the ecosystem. Almost all of the energy in living things on earth ultimately comes from the sun.<\/p>\n<p><center><img decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/biology\/wp-content\/uploads\/sites\/2\/2017\/08\/foodchain2.jpg\" alt=\"Basic food chain\" \/><\/center>All organisms need energy. <abbr title=\"organisms such as plants that can convert the sun's energy into chemical energy that will be used by other living things Autotrophic organisms are called primary producers and are the base of any food chain\">Autotrophic<\/abbr> organisms, such as plants and photosynthetic protists and bacteria, can convert the sun\u2019s energy into the chemical energy that is used by all living things. Autotrophic organisms are called <abbr title=\"organisms that produce their own food; plants convert the sun's energy into the chemical energy used by all living things\">primary producers<\/abbr>, and are the base of any food chain, the lowest trophic level. Some bacteria are <abbr title=\"organisms that can produce organic nutrients from inorganic matter using chemical energy Some bacteria are chemoautotrophs\">chemoautotrophic<\/abbr>, meaning they can produce organic nutrients from inorganic substrates using chemical energy.<\/p>\n<p><abbr title=\"organisms that are unable to produce their own food and are reliant upon the consumption of other organisms\">Heterotrophic<\/abbr> organisms cannot produce their own food and so must consume other organisms. Primary <abbr title=\"organisms unable to produce their own food; obtain all of their nutrition through consumption of other organisms \">consumers<\/abbr> are the <abbr title=\"consumers that rely on plant material or producers for their nutritional needs\">herbivores<\/abbr> that eat the producers. They occupy the second trophic level in the food chain. Secondary consumers feed on other consumers; they are <abbr title=\"consumers that obtain all of their nutritional requirements by eating other animals\">carnivores<\/abbr>. Top consumers, such as humans, are often omnivores meaning they have diverse diets of both plant and animal foods. They are characterized by being at the top of the food chain.<\/p>\n<p><abbr title=\"organisms, such as bacteria and fungus, that survive on the waste product of ecosystems, playing an important role as recyclers\">Detritivores<\/abbr>, such as worms, and <abbr title=\"organisms that feed on and break down dead organisms to recycle nutrients back into the ecosystem\">decomposers<\/abbr>, such as bacteria and fungi, are important in recycling nutrients. They get their energy by feeding on dead organisms, either by actively ingesting them or by breaking them down and absorbing nutrients. When they do so, complex organic macromolecules are broken down into simpler forms and are returned to the environment. In nature, simple food chains are more likely to be complex food webs that continue the processes of energy transfer and cycling of nutrients.<\/p>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>A housecat eats a bird, which has eaten a caterpillar that feeds on leaves. Which trophic level describes the house cat?<\/p>\n<ol>\n<li>Primary producer<\/li>\n<li>Primary consumer<\/li>\n<li>Secondary consumer<\/li>\n<li>Top consumer<\/li>\n<\/ol>\n<p><a class=\"q-answer button button-primary\">Reveal Answer<\/a><\/p>\n<p class=\"q-reveal\">D is the correct answer. The housecat is the top consumer in our food chain example. The leaf is the primary producer and the caterpillar the primary consumer. The bird is the secondary consumer.<\/p>\n<\/section>\n<p>A simple food web might look like this: In a meadow, grass, wildflowers, and a few small shrubs are the primary producers. Insects, mice, and rabbits all feed on the plants and seeds. Some insects feed on decomposing organic matter or parasitize animals. Some bird species also feed on seeds, while others eat insects and earthworms. Snakes feed on mice, rabbits, and birds. Falcons eat mice, rabbits, and snakes. Bacteria and fungi decompose dead plants and animals, and earthworms break down other dead organic material.<\/p>\n<p><center><img decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/biology\/wp-content\/uploads\/sites\/2\/2017\/08\/BioMod-31.2-food-chain.jpg\" alt=\"Food web\" \/><\/center>As you can see, food webs can be very complex. In this example, the plants are primary producers and the falcon is a top consumer. Bacteria and fungi are decomposers and earthworms are detritivores. The mice and rabbits are herbivorous primary consumers. All of the other organisms listed have some overlap in trophic level. The same is true of humans. Some are primary consumers, while others are top consumers.<\/p>\n<p>Most of the energy in any ecosystem is at the lowest trophic level, the primary producers. At each trophic level, about 90% of the available energy is used by an organism to grow and reproduce or is lost as heat; only 10% is transferred to the next level. Because of this, it takes many primary producers to support a few top consumers. For every 1,000 calories of energy present in the primary producers of an ecosystem, only 1 calorie is available for a top consumer. At the same time, environmental pollutants become more concentrated at each trophic level. That is why top consumers like birds of prey and humans are particularly susceptible to pollutants such as DDT.<\/p>\n<p><center><img decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/biology\/wp-content\/uploads\/sites\/2\/2017\/08\/BioMod31.2_toxin_effect.jpg\" alt=\"Consumers and toxin concentrations\" \/><\/center>While there is a one way flow of energy through ecosystems, matter is constantly recycled through biogeochemical cycles. Examples of <abbr title=\"the constant recycling of energy through ecosystems as a result of processes such as the water, nitrogen, and carbon cycles\">biogeochemical cycles<\/abbr> include the water cycle, the carbon cycle, and the nitrogen cycle. Biotic processes such as photosynthesis and respiration, transpiration, and nitrogen fixation all play a role in the cycling of materials on earth.<\/p>\n<h3>Summary<\/h3>\n<ul>\n<li>Ecosystems are composed of biotic communities and the abiotic environment.<\/li>\n<li>There is a one way flow of energy through the various trophic levels of communities.<\/li>\n<li>There is continuous cycling of materials through the biotic and abiotic components of the ecosystem.<\/li>\n<\/ul>\n<\/section>\n<p><!-- CONTENT ENDS HERE --><\/p>\n<div class=\"advance\"><a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/biology\/human-body-systems\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/biology\/basic-science-core\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/biology\/further-reading\">Further Reading \u27a1<\/a><\/div>\n<p><a class=\"backtotop\" href=\"#title\">Back to Top<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u2b05 Previous Lesson\u00a0Workshop Index\u00a0Further Reading \u27a1 Ecosystems Objective In this lesson, you will review the components of ecosystems. Scientists, regardless of their specialization, need to possess a basic level of science literacy across all disciplines. This lesson provides an overview of the major concepts pertaining to ecosystems that all students of the sciences should know. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-488","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/pages\/488","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/comments?post=488"}],"version-history":[{"count":6,"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/pages\/488\/revisions"}],"predecessor-version":[{"id":570,"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/pages\/488\/revisions\/570"}],"wp:attachment":[{"href":"https:\/\/americanboard.org\/Subjects\/biology\/wp-json\/wp\/v2\/media?parent=488"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}