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Introduction to Ecology: The Biosphere. A. Interactions and Interdependence 1. Ecology: the scientific study of interactions among organisms and between

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  • Introduction to Ecology: The Biosphere

  • A. Interactions and Interdependence1. Ecology: the scientific study of interactions among organisms and between organisms and their environment2. Biosphere: portions of the Earth in which all of life exists, includes land, water and aira) Ranges from surface to 8 km above and 11 km below

  • BiosphereEcosystemCommunityPopulationThe part of Earththat contains allecosystemsCommunity and its nonliving surroundingsPopulations thatlive together in a defined areaGroup of organisms of onetype that live in the same areaBiosphereHawk, snake, bison, prairie dog, grass, stream, rocks, airHawk, snake, bison, prairie dog, grassBison herdLevels of Organization

  • OrganismGroups ofCellsCellsMoleculesIndividual livingthingTissues, organs,and organ systemsSmallest functionalunit of lifeGroups of atoms;smallest unit of most chemicalcompoundsBisonNervous tissueNervous systemBrainNerve cellWaterDNA

  • Section 3-1

  • Producers1. The Sun is the main energy source for life on Earth.Less than 1% of all sunlight is used by living things.2. Some organisms rely on the energy stored in inorganic chemical compounds (chemosynthesis)

  • 3. Autotrophs can capture energy from sunlight or chemicals to produce food (plants, some algae and bacteria).Energy is used to combine simple inorganic compounds into complex organic moleculesResulting organic molecules combine and recombine to make living tissue.

  • b) Photosynthesis: light energy used to power chemical reactions that convert CO2 and H2O into O2 and carbohydrates (such as sugar and starch)

  • Photosynthesis is responsible for adding oxygen and removing CO2 from the atmosphere.Performed by plants, algae and some bacteria (ex:cyanobacteria)

  • c) Chemosynthesis uses energy within chemical bonds of inorganic molecules to produce carbohydrates1) performed by several types of bacteria

  • ConsumersHeterotrophs rely on other organisms for their energy needsa) herbivores consume plantsb) carnivores consume animalsc) omnivores consume plants and animalsd) detritivores consume organic remains and dead mattere) decomposers break down organic matter

  • Energy flows in one direction through an ecosystem, from the sun or inorganic compounds to producers (organisms that can make their own food) through various levels to consumers (organisms that rely on other organisms for food). Your body gets the energy and materials it needs for growth and repair from the foods you eat.

    Feeding Relationships

  • 2. Food Chain: a series of steps in which organisms transfer energy through feeding

  • Food Chains

  • 3. Food Web: demonstrates the complex interactions between the organisms in food chains in an ecosystem.The base of a food web is occupied mostly by vegetation (producers) and fine organic debris (decomposers). Herbivores (primary consumers) and carnivores (secondary consumers) occupy the higher levels. Omnivores occupy an intermediate level in the food web.

  • 4. Trophic level: each step in a food chain or food web.

  • D. Ecological PyramidsShows the relative amounts of energy or matter contained within each trophic level.Energy PyramidOnly ~ 10% of the energy in a trophic level can be transferred to the next level (can range from 0.05 to 20%The more levels that exist between a producer and a top-level consumer the less energy remains from the original amount.

  • 2. Biomass PyramidBiomass: the total amount of living tissue within a trophic level.represents the amount of potential food available for each trophic level3. Pyramid of Numbersa) Based on the actual numbers of organisms at each trophic level.

  • Pyramid of NumbersShows the relativenumber of individualorganisms at eachtrophic level.Biomass PyramidRepresents the amount ofliving organic matter at each trophic level. Typically, thegreatest biomass is at the base of the pyramid.Energy PyramidShows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat.Energy Pyramids

  • III. Cycles of MatterRecycling in BiosphereMatter is recycled within and between ecosystems.a) Biogeochemical cycles: connect biologic, geologic and chemical portions of the biosphere through the conversion of elements, chemical compounds and other matter between organisms and their environment.

  • b) Matter can cycle because biologic systems do not use up matter they transfer it into living tissue or pass it as waste products

  • B. The Water CycleThe process by which water is moved through the biosphereEvaporation: water changes to gaseous form by absorbing energyTranspiration: loss of water through leaves due to evaporationCondensation: changing of water from gas to liquid by releasing energyPrecipitation: movement of water from atmosphere to surface as rain, snow, hail or sleet.

  • It is estimated that a single drop of water can take 4000 years to complete the water cycle.

  • CondensationSeepageRunoffPrecipitationRootUptakeWater Cycle

  • C. Nutrient CyclesNutrient: chemical substances required for life functions and growthnutrients are passed between organisms and the environment through biogeochemical cycles1) Prevents dangerous levels of nutrients (too high to too low)

  • 2. Carbon CycleImportant because carbon is the key ingredient in all living organismsLess than 1% of all C on Earth circulates in the biosphere1) ~ 71% in oceans as CO3 and Ca(CO3)2, 22% in fossilized carbon

  • b) 4 main processes for carbon cyclingBiological processes (e.g.: photosynthesis, respiration, decomposition)Geological processes (e.g.: volcanic outgassing, absorption in ocean/precipitation)Mixed biogeochemical processes (e.g.: creation of fossil fuels, limestone)Human activity (e.g.: mining, burning of fossil fuels and forests)

  • CO2 inAtmosphereCO2 in OceanCarbon Cycle

  • Global WarmingGlobal warming is an observed increase in the average temperature of the Earth's atmosphere and oceans.

  • Part of this increase may be due to natural processes, and would have occurred independently of human activity. The remainder is due to a human-induced intensification of the greenhouse effect. The increased volumes of carbon dioxide and other greenhouse gases released by the burning of fossil fuels, land clearing and agriculture, and other human activities, are the primary sources of human-induced warming

  • Greenhouse EffectGreenhouse gases (GHG) are gaseous components of the atmosphere that contribute to the greenhouse effect. The major natural greenhouse gases are water vapor (36-70% of the greenhouse effect); carbon dioxide (9-26%); and ozone (3-7%)

  • 3. Nitrogen CycleImportant because N is used to make amino acids which are used to build proteins.Occurs in many forms, 78% as nitrogen gas (N2)1) Ammonia (NH3), nitrate ions (NO3-) and nitrite ions (NO2-) from dead and decaying matter.

  • b) Nitrogen fixation: conversion of N2 (gas) into NH3 by bacteria in soil or on legumes (roots of certain plants)1) Decomposers further converted NO3- and NO2- ions which can be used by producers to make proteins.

  • C) decomposers return nitrates to soil as ammonia to be used againD) soil bacteria convert nitrates into N2 (denitrification)

  • N2 in AtmosphereNH3NO3-and NO2-Nitrogen Cycle

  • 4. Phosphorus CycleImportant because used in DNA and RNA Not very common, found in rock and soil minerals and ocean sediments1) Note that it is not found in the atmosphere

  • b) As rocks and sediments erode, phosphate is released and may be dissolved in waterUsed by marine organisms in the oceansSome phosphate remains on land and cycles between organisms and the soilPlants absorb phosphate and bind it into organic compoundsOrganic compounds move through the food web

  • 5. Nutrient LimitationPrimary productivity: rate at which organic matter is created by producers.1) Depends on recycling of available nutrients if any are in short supply it will limit an organisms growth.

  • b) Limiting nutrient: a nutrient that is scare or cycles very slowly and limits growth in an ecosystem.1) Fertilizer used to compensate for limiting nutrients (N,P and K)

  • c) Oceans are (by their nature) nutrient-poor compared to the land.Algal bloom: an increase in the amount of algae and other producers due to an increase of limiting nutrient(s).i) If there are not enough consumers, an algal bloom can upset the health of an ecosystem by oxygen depletion from bacteria during decomposition of dead algae.

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