SCIENCE 20 UNIT D: Changes in Living Systems Chapter 1: Biosphere of Life Chapter 2: Changing Populations Chapter 1: Biosphere of Life 1.0: Introduction 1.1: Abiotic factors 1.2: Biotic factors 1.3 The Web of Life 1.4 Conducting a Field Study 1.5 The Recycling of Matter 1.6 Biodiversity Lesson 1.0: Introduction The Biosphere • The biosphere is the area of the earth that supports life. • It consists of the: – atmosphere or air – hydrosphere or water – lithosphere or land. Ecology • “Ecology is the study of the biosphere.” – Study of the interactions of living organisms with one another and with their physical environment Main interactions in biosphere •The sun is the primary source of energy •Producers change solar energy into chemical energy. •Consumers eat producers & other consumers. •Decomposers break down the waste materials into abiotic chemicals which can be used by plants. •Waste energy is released as heat or thermal energy. •Abiotic factors are non-living structures, while biotic factors are living structures that interact in the biosphere. The Habitat is all the biotic and abiotic factors present in an area that encourage the reproduction and survival of an organism. The Organization of Biosphere Biosphere: Area that supports life ie) Earth Ecosystems: all the organisms & interacting abiotic factors in an area ie) Prairie grasslands Communities: several populations ie) deer and humans Populations: Group of individuals ie) herd of deer Organisms: a single plant or animal ie) deer How is the energy from the sun captured? • Plants & algae capture energy from the sun during photosynthesis: 6CO2(g)+6H2O(g)+solar chloroplast C6H12O6 (s)+6O2 (g) • Plants make two vital components for life: oxygen and glucose or food. • Since plants make their own food they are often called autotrophs or “self feeders”. How is energy stored in glucose released? • Plants and animals release energy stored in glucose during cellular respiration: C6H12O6 (s)+6O2 (g) mitocondria6CO2(g)+6H2O(g)+Energy • NOTE: The Cellular respiration reaction is the photosynthesis reaction backwards. See What You Know Lesson 1.1: Abiotic factors What are abiotic factors? • Abiotic factors are the non-living components that influence and shape an ecosystem. • They are classified into three general categories: climatic, physiographic and edaphic. • They are vital to an ecosystem because they affect the type and number of organisms that live there. Five Climatic Factors: • Light: The amount of light affects the rate of photosynthesis, which determines the amount and type of plants in the ecosystem. • Temperature: The temperature range of an ecosystem sets limits to the type of organism that can survive. Life on earth exists between –60oC to + 60oC. • Moisture: Water is necessary for life & influences the adaptations plants and animals have to survive. In low moisture areas, plants have waxy leaves and animals have skin to hold in the moisture. • Wind: Wind affects the composition. Windy ecosystems will encounter soil movement & water loss due to evaporation & transpiration. • Fire: Fire causes major changes to ecosystems and may be a necessary. Jack pine cones will only reproduce after a fire and fire beetles mate and lay eggs under the burned bark. Three Physiographic Factors: • Latitude: As the latitude increases (towards north & south poles), temperatures decrease, greater variation in light occurs and diversity of species decreases. • Altitude: At higher altitudes (higher up the mountain), temperature decrease, precipitation increases, wind increases and soil conditions worsen. • Topography (physical features of the land): The physical features of land such as mountains, hills, flatlands and valleys can affect factors of an ecosystem such as precipitation. The Rocky Mountains creating dry warm Chinook winds are an example of a topographic factor affecting an ecosystem (look below). Two Edaphic Factors: • Edaphic factors are factors related to the texture and chemical composition of the soil. • FACTORS: Slope, organic content, age, particle size, ionic content and minerals present • Edaphic factors determine what type of plant growth can be supported. 4 Typical Layers •twigs and leaves. •dead and decaying material. •clay and minerals •Bedrock & glacier deposits Lesson 1.2: Biotic Factors What are biotic factors? • Biotic factors are the “living” interactions between organisms in an ecosystem. There are three main biotic factors – symbiosis, predation, and competition. What is Symbiosis? • Symbiosis describes close relationships between two or more species and a least one benefits. There are 3 types of symbiotic relationships – Commensalism is a relationship where one organism benefits & the other is unaffected. • Ie) cowbirds & bison – the bison stirs up insects for the cowbird. • Ie) birds nesting in trees - the birds benefit and the tree is unaffected. – Mutualism is a relationship where both organisms benefit. • Ie) Prairie dogs aerate the soil and increase rich plant growth and the buffalo compacts the soil (better burrows) and keeps the plants short so the prairie dogs can see predators. • Ie) Another example is the crab (provides protection) and the stinging anemone (provides larger feeding area). – Parasitism is a relationship where one organism benefits and the other is harmed. • Ie) Cowbirds lay their eggs in the yellow warbler nests • Ie) The tapeworm benefits by eating the nutrients in the intestine, while the individual suffers weight loss/sickness. What is predation and intrusion? • Predation: relationships where the prey (organism eaten) becomes food for the predator (organism hunting). – ie) Lynx & hare are an example of a predator-prey relationship – ie) The Venus Fly Trap is a rare example of predation by a plant. • Occasionally, an intruder is introduced to a ecosystem where there are no predators. – ie) Zebra Mussels or the West Nile Virus. •The prey population is larger to provide the predator with a better chance of survival. • The delay is due to time for reproduction. What is Competition? • Competition describes relationships where organisms compete for limited resources, territory or members of the opposite sex. – Ie) Two mountain goats fighting for a female – Ie) two coyotes fighting for food – Ie) Grass & wildflowers (coneflower) compete for light, water & nutrients Lesson 1.3: The Web of Life How does energy flow? • Energy levels are called trophic levels 5th trophic level – decomposers (present after each level) 4th trophic level – 3rd order (tertiary) consumers 3rd trophic level – 2nd order (secondary) consumers 2nd trophic level – 1st order (primary) consumers 1st trophic level – autotrophs or producers How does energy flow? • Energy levels are called trophic levels • 1st TROPHIC LEVEL: AUTOTROPHS – can trap and change light energy to chemical energy; all other organisms depend on them. – Also called producers – Plants and algae are autotrophs How does energy flow? • 2st TROPHIC LEVEL: 1st CONSUMERS – feeds directly on a producer – are also called primary (first order) consumers, herbivores, or plant eaters. – A cow grazing on grass, a caterpillar browsing on leaves and a tadpole eating algae are examples of herbivores. How does energy flow? • 3rd & 4th TROPHIC LEVEL: 2nd & 3rd ORDER CONSUMERS – feeds directly on other consumers – are also called secondary & tertiary consumers, carnivores, or animal eaters. – A fox which eats a bird is an example of a carnivore How does energy flow? • 5th or LAST TROPHIC LEVEL: DECOMPOSERS – feeds on the waste or dead material in the tropic level(s) below – Recycles the nutrients for producers – Bacteria & mushrooms are examples of decomposers. What are food chains? • Food chains are an oversimplified means of showing how the Sun's energy is passed from one organism to another. All food chains begin with a producer and have the following basic format: Producerconsumer(herbivore)consumer(carnivore)... Energy flow What are food webs? • A food web is several food chains interconnected. • It is organized with the trophic levels in rows & interconnected with arrows, like the one on the right. What are pyramids? • Pyramids are triangles or horizontal bar graphs that illustrate energy loss, numbers of organisms involved or biomass. • Three pyramids examined in this course are: – Energy pyramids – Number pyramids – Biomass pyramids What are energy pyramids? • Energy pyramids are organized by the amount of energy available in each trophic level. • Rule: 90% of energy is used for life processes or lost as heat; 10% of energy is stored and passed on to the next consumer. What are number pyramids? • Number pyramids are organized by the number of organisms present in each trophic level. Due to energy used for live processes, it takes a great number of producers to supply the energy needs of a primary consumer. What are biomass pyramids? • Biomass pyramids are organized by the mass of all the organisms in that trophic level. • Mass decreases as energy flows up the pyramid. What is Biomagnification? • Biomagnification is also known as biological amplification. • Biomagnification occurs when a chemical increases in concentration as it moves up the food chain/web because the chemical becomes stored in the organisms tissues. TOPIC 1.4: Field Study (See handout) TOPIC 1.5: Recycling Matter What is the hydrologic cycle? • The hydrologic (water) cycle is the movement of water between the hydrosphere, lithosphere and atmosphere. The energy that runs the water cycle comes from the sun. What are the steps of the hydrological cycle? 1. Evaporation (water turns into vapour) and transpiration (plants and animals releasing water vapour during cellular respiration) puts water vapour into the atmosphere. 2. The vapour condenses into clouds as the air rises & cools. 3. Precipitation (rain, snow, hail, dew or fog) returns water to the hydrosphere and lithosphere. 4. Run-off pools water into rivers, lakes and oceans so organisms can use it. Run-off also free minerals and nutrients that are needed by organisms. 5. Underground aquifers return the ground water from the lithosphere to the hydrosphere. What human activities affect the water cycle? • Wildfires produce a waterproof layer and remove trees which increase run-off and erosion. Trees regulate temperature and moisture • Potable water (water usable for human consumption) is an ever-increasing problem because of the lack of water in some areas and pollution in other areas (sewage, pesticides, acid rain, heavy metals, etc…) • Aquifers provide water for people in areas where there is not very much surface water. • Removal & overuse of too much water dries up lakes, rivers and aquifers. • Changing climates also change the water cycle patterns. What is the carbon cycle? • Carbon is the basic building block of all life on Earth. Carbon exists in the atmosphere as carbon dioxide(CO2) and exists as sediments (CaCO3) in the soil. • Contributors: cellular respiration, decomposition, weathering, volcanoes and combustion. •Depleters: photosynthesis and formation of minerals What is the oxygen cycle? • The oxygen cycle recycles oxygen throughout the biosphere. Some of the oxygen is found as a gas (O2(g)) and is often called the global free oxygen supply. 21% of the atmosphere is free oxygen. • Most of the oxygen in the biosphere is combined with other chemicals: glucose (C6H12O6(s), carbon dioxide (CO2 (g)), water (H2O (g)), calcium carbonate (CaCO3) & ozone(O3 (g)). What are the Contributors & Depleters of atmospheric oxygen? • CONTRIBUTORS: Photosynthesis, Weathering of Sediment & Ozone break- down. • DEPLETERS: Cellular Respiration, Decomposition, Combustion, Ozone formation & Inorganic mineral formation What human activity affects the oxygen and carbon cycle? • Wildfires, Burning wood and fossil fuels uses up free oxygen and increases the amount of carbon dioxide. Large amounts of carbon dioxide in the atmosphere traps heat, which affects climate and creates global warming. • Deforestation, building on productive land and polluting the land & water reduces photosynthetic organisms, which also lowers the free oxygen supply. • Using Chlorofluorocarbons (CFCs) in hairspray and cups reduces the amount of ozone (O3) in the upper atmosphere, which allow harmful UV rays through. • Recycling materials allows humans to reduce the amount of energy (fossil fuels) and materials needed. What is the nitrogen cycle? • Note the four processes in the nitrogen cycle below – fixation, ammonification, nitrification, denitrification What is the nitrogen cycle? • Nitrogen is an important element for life. Nitrogen is the building block of amino acids, which are found in muscles, DNA and plant chlorophyll. Four processes cycle nitrogen through the ecosystem: – Nitrogen fixation is a two-step process where rhibizom bacteria (attached to the roots of plants), lightning or the fertilizer industry changes nitrogen gas to ammonia (fertilizer). • N2(g) 2 N(aq) + 3H2(g) 2NH3(g) – Ammonification is another process where fungi and some bacteria decompose waste, producing ammonia from the nitrogen found in the waste. • CH2NH2COOH(s) + 3O2(g) 2NH3(g) + 4CO2(g) + 2H2O(l) – Nitrification is the process where bacteria convert ammonia to nitrite and then to nitrate. (Some plants use the nitrate produced during nitrification.) • 2NH3(g) + 3O2(g) H2O(g) + H+(aq) + NO2-(aq) • NO2-(aq) + O2(g) NO3-(aq) – Denitrification is the process where bacteria change the nitrates back to nitrogen gas. What human activities affect the nitrogen cycle? • Wide scale cultivation of legumes (plants that fix nitrogen) and industrial fixation of nitrogen to produce fertilizers have started to deplete the amount of nitrogen in the atmosphere. • Over fertilization has resulted in excess nitrogen and phosphorus running into rivers and lakes. This has resulted in increase growth of algae and plants. When the algae and plants die, decomposers use up the valuable oxygen in the water, killing fish and other oxygen-dependent organisms. How are the biochemical cycles interconnected? • Oxygen is found in all the cycles. • Reforestation will increase the amount of nitrogen used in the soil (nitrification) and increase the amount of oxygen released into the atmosphere, but it will decrease the amount of carbon dioxide & water in the atmosphere. • Preserving wetlands would increase ammonification and photosynthesis, increasing the amount of nitrogen and oxygen available for the ecosystem. TOPIC 1.6: Biodiversity What is Biodiversity? • Biodiversity is the variety of ecosystems, species and genes in an area. Boreal forests and rain forests have more biodiversity. What is the connection between the caribou and food packaging? • The woodland caribou need a forest that is older than 80 years to grow enough tree lichen, their main winter food. • Food packaging comes from oil and natural gas. Oil and natural gas companies cut down the trees in the north for exploration and removal. • This tree removal has contributed to making the caribou a endangered species (may soon no longer exist) and decreasing the biodiversity. What are the categories of species risk? What affects biodiversity and endangers species? 1. Habitat Fragmentation 2. Habitat destruction 3. Clash between ecological systems and economic systems What is Habitat Fragmentation? • Habitat fragmentation is the change of a complete habitat into patches separated by non-habitat areas. This is caused by building houses, farms and seismic lines What is Habitat Destruction? • Habitat destruction is the permanent alteration of vital characteristics in an organism’s habitat. Ie) trees in the forest What is the difference between the ecological and economic systems? Chapter 2: Populations 2.1 Primary Succession 2.2 Secondary Succession 2.3 Populations 2.4 Adaptations 2.5 Evolutionary Theory TOPIC 2.1: Primary Succession TOPIC 2.2: Secondary Succession What is succession? The natural change in the types & numbers of species in a community is called ecological succession. 1. First a pioneer community (first community), like bacteria or lichen invades the ecosystem. Chemicals from the lichens and bacteria, along with weathering break down rocks into fertile soil. 2. Eventually plants species, like mosses and grass start to grow in the soil. 3. Next herbs and flowers invade the grass community. 4. Shrubs begin to grow and out-compete the herbs and grasses. 5. Eventually trees like poplars and spruce trees begin to grow. This dominant, stable species is called the climax community. What are the two types of succession? • Primary succession starts in an ecosystem where no life has existed before, such as new lakes, volcanoes, deltas and sand dunes. • Secondary succession occurs in an ecosystem that has been disturbed by fire, floods or human activities and is more common & quicker than primary succession. TOPIC 2.3: Populations Def: Number of individuals living in a given area What is happening to the human and some organism population? • Human and many microscopic populations rapidly increasing by constantly doubling (time it takes is called the doubling time); this growth is called exponential growth and it produces an exponential (J) curve (below). What are the 4 factors affecting populations? • Populations increase because of 1) births & 2) immigration (movement in). • Populations decrease because of 3) deaths & 4) emigration (movement out). • Closed populations are only affected by births and deaths. Ie) zoo • Open populations are affected by all 4. ie) National parks What causes population explosions, & crashes? • Populations explode (increase rapidly) when there is plenty of food &/or no predators. • Populations crash (decrease rapidly) when there is little food &/or several predators What is carrying capacity & a S-curve? • Carrying capacity is the maximum number of individuals that a given ecosystem can sustain. • S-curve is the shape of a population graph limited by disease, competition and famine • The human population has not reached it’s carrying capacity TOPIC 2.4 Adaptations Why does variation exist? • Variation exists because the genes in DNA (genetic blueprint or code) can mutate. • Mutations are changes in instructions from a gene. • Mutations that aid an organism are passed on to their offspring. • The greater the genetic variation, the better a population can respond to environmental changes. How do populations change? • Very gradual changes in populations is called gradualism. • Sudden changes in populations is called punctuated equilibrium. What are adaptations? • Inherited traits that increase an organism’s chance for survival are called adaptations. There are three types of adaptations: – Structural: a physical adaptation that helps them survive or reproduce. E.g) Fur is an example of an adaptation for animals living is cold regions. – Physiological: an adaptation that helps an organism with a biological process. E.g.) Colored pigments help flowers attract pollinators. – Behavioral: an action that helps an organism survive or reproduce. E.g.) A mating dances to ensure reproduction is an example. TOPIC 2.5: Evolutionary Theory After observations on the Galapagos Islands, Darwin published On the Origin of Species in 1859. Galapagos Finches • Selection pressures are conditions such as food & habitat, which result in new adaptations/traits What is Darwin’s Theory of Natural Selection? Charles Darwin, from his travels, made 3 observations: 1. Organisms produce more offspring than can survive. 2. Variation exists among individuals of a species. 3. Organisms compete with each other for limited resources. • From these observations, Darwin proposed the theory of natural selection – organisms best suited for their environment survive, reproduce and pass on these traits. – Eg) Peppered Moth: when coal was burned the black moth was more common; when coal burning stopped, the gray moth became more common What is the theory of Evolution? • Darwin suggested that natural selection could also create a new species called speciation. • Theory of Macro Evolution is an explanation of how many slow changes over time created by natural selection eventually resulted in the creation of a new species. • Theory of Micro Evolution is an explanation of how many small changes over time created by natural selection result in changes within a species. • The reproductive success of an organism is now called its Darwinian fitness. • Evolution is also called the survival of the fittest. What are the essential requirements for Natural selection? 1. There must be a genetic basis for variation 2. The new trait must increase the rate of survival and/or rate of reproduction. 3. The environment and/or catastrophes play an important role What role did Alferd Wallace & Jean-Baptiste Lamarck have? • Wallace came to similar conclusions as Darwin • Lamarck proposed that organisms change during their lives to meet the challenges of their environment. Eg) giraffe necks became long due to stretching for higher leaves. The stretched neck trait was passed on. • Both Wallace and Lamarck started people thinking about how and why organisms change. What evidence is there for evolution? 1. Fossils provide a history of the past. 2. Embryology: species that are related have embryos (babies) that are very similar. What evidence is there for evolution? 3. Comparative Anatomy shows that species that are related have structures that are similar. Homologous structures have similar origin but different uses. Ie) human arm, whale flipper & bat wing What evidence is there for evolution? 4. Vestigial structures (structures with no use) suggest that through adaptation the use of these structures has been lost 5. Biochemistry indicates the species that are related have similar chemical make-up. Ie) the DNA of cats and dogs is almost the same. 6. Biogeography – organisms separated by geography have similar characteristics suggests they may have had a common ancestor What are some other theories? • Punctuate Equilibrium and Creation are two other theories that describe how speciation occurred. – Punctuate Equilibrium states that very sudden changes in the environment forced organisms to adapt very quickly. – Creation states that a higher being created the species with similarities to each other. Evidences that support Creation 1. Very complex design –statistical impossible that if evolved randomly – Cells have thousands of complex functions 2. Lack of transitional fossils 3. Signs of devolution: – Increase in number of disorders – Lose of species and diversity – Decreasing magnetic field strength Evidences that support Creation 4. Supports the 2nd Law of Thermodynamics: the universe is going from a state of order to a state of disorder 5. Redshift and “Hubbles Law” states that the universe is expanding; therefore the universe had a beginning. 4. DNA or the genetic code is complex indicating intelligent design. – The information stored on the DNA of one bacteria could fill all the books in one of the largest libraries of the world.
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