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Ch 3: The Biosphere Studying Our Living Planet Biosphere: all life on Earth and all parts of the Earth in which life exists Eco = oikos, meaning house Ecology: study of interactions among & between living organisms and their physical environment Levels of Organization Ecologists have organized the interactions an organism takes part in into different levels according to complexity. Ecological Levels of Organization 1st Level of Organization Organism/Individual: A living thing that is made of cells, uses energy, reproduces, responds, grows, and develops—is part of a species Species: group of similar organisms that can breed & produce fertile offspring 2nd Level of Organization Population: A group of organisms, all of the same species, which interbreed and live in the same place at the same time. 3rd Level of Organization Biological Community: All of the populations of different species that live in the same place at the same time. 4th Level of Organization Ecosystem: Populations of organisms that interact with each other and with the environment of a given area. 5th level of Organization -Biomes are a group of ecosystems with similar climates and typical organisms. 6th Level: The Biosphere Life is found in air, on land, and in fresh and salt water. The BIOSPHERE is the portion of Earth that supports living things. Biotic and Abiotic Factors Biotic factor – living components of the environment with which an organism may interact; all of the biological influences on organisms --Ex: Plants, Animals, Fungi, Protists, Bacteria Abiotic factor – any nonliving part of the environment that affects the organism --Ex: Sunlight, heat, precipitation, humidity, wind, water currents, soil type, etc. Abiotic or Biotic? Biotic Abiotic or Biotic? Abiotic Abiotic or Biotic? Abiotic Abiotic or Biotic? Biotic Energy, Producers, & Consumers Living systems operate by using energy Need energy for: growth, reproduction, metabolism, etc. Organisms can only use energy from other sources Where do you get your energy from?? Where does the energy in food come from??? What is our Planet’s Energy Source? For most life on Earth, sunlight is the ultimate energy source For some organisms energy stored in chemicals in rocks, soil, etc., serves as their primary energy source Primary Producers (Autotrophs) • • • • Organisms that produce their own food supply Cells of most autotrophs contain chlorophyll & can use energy directly from the sun Ex: plants, attached algae, freefloating algae (phytoplankton), & some bacteria May be photoautotrophs using light energy (e.g. plants) May be chemoautotrophs using chemical energy (e.g. some bacteria) Photosynthesis Chemical reaction where producers use water and carbon dioxide to store the sun’s energy as glucose. 6H2O + 6CO2 + Sun C6H12O6 + 6O2 20 Chemosynthesis Chemical reaction where producers use chemicals and carbon dioxide to store energy as glucose. Consumers (Heterotrophs) Eat other organisms to obtain energy. Ex: animals, fungi, protists, & many bacteria Herbivores --Eat only plant products (leaves, roots, seeds, or fruits) --Ex: Cows, caterpillars, deer Carnivores --Eat only other animals --Ex: Snakes, dogs, cats, otters Omnivores --Eat plant products & animals --Ex: Humans, bears, pigs, raccoons Scavengers --Eat carcasses of other animals killed by predators or died of natural causes --Ex: Vultures Decomposers --`feed’ by chemically breaking down organic matter; produces detritus (small pieces of dead & decaying plant & animal remains) --Ex: Bacteria & fungi Detritivores --Consume detritus & the decomposers that live on/in detritus --Ex: Earthworms, mites, snails, shrimp, crabs Feeding Relationships Energy flows through an ecosystem in one direction: from producers to various levels of consumers Food Chain Series of steps in which organisms transfer energy by eating & being eaten Food Web More realistic path through an ecosystem—made of many food chains (because organisms may eat more than one kind of food!) Food Webs Are interconnected food chains They show the feeding relationships in an ecosystem Food Chain 1st Order Consumer Producer (trapped sunlight & stored food) 2nd Order Consumer 3rd Order Consumer 4th Order Consumer Trophic Levels Levels through which energy flows in an ecosystem Each step taken in a food chain or web is called a trophic level 1st level: Primary producers 2nd level: Primary consumers 3rd level: Secondary consumers 4th level: Tertiary consumers Food Chains Show Available Energy What happens to the energy? Most of the energy the primary consumer gets Some of the energy moves into the atmosphere Rule of 10: Only about 10% of energy is transferred from one trophic level to the next. The rest is used for life functions (growth, reproduction, etc)! from the producer is used by the consumer as heat. Example: It takes 100 kgs of plant materials (producers) to support 10 kgs of herbivores It takes 10 kgs of herbivores to support 1 kg of 1st level predator Ecological Pyramids Another way of showing the relative amount of energy or matter contained in each trophic level 3 different types: --Energy --Biomass --Numbers Ecological Pyramids Show Energy Pyramids: Amount of available energy at each trophic level Only 10% of energy is transferred from one level to the next. Biomass Pyramids: Amount of living organic matter available at each trophic level (grams/kg) Numbers Pyramids: Number of individual organisms at each trophic level (population size) 30 Ecosystem Recycling: Cycles of Matter All ecosystems must have cycles of systems to reuse raw materials (there is not an infinite amount of resources!!!) Matter is recycled within & between ecosystems Biogeochemical Cycles: closed loops that allow matter to be recycled through biological, geological, & chemical (physical) processes Water Cycle Carbon Cycle Nitrogen Cycle Phosphorus Cycle Water Cycle • • • • • Evaporation Transpiration Precipitation Runoff Groundwater Steps of the Water Cycle Water vapor in the air condenses and falls as rain or snow. 2A. Some rain/snow seeps into soil and becomes part of groundwater. 2B. Most rain/snow falls into the ocean. 3A. Water is heated by the sun and evaporates. 3B. Plants absorb water that is in the ground. 4. After going through the plant, the sun and wind pulls water out by evaporation – process called transpiration. 1. Nitrogen/Phosphorus Cycle • Found in atmosphere, runoff, fertilizersdue to decomposition • Nitrogen & phosphorus are used in the synthesis of amino acids (proteins), nucleic acids (DNA), & energy molecules (ATP) • Nitrogen/Phosphorus fixing (converting): done by bacteria/fungi; change nitrogen/phosphorus compounds into a usable form for plants • Nitrogen/Phosphorus in soil is then absorbed by plants and becomes part of the plant’s tissues • Plants are consumed by herbivores or omnivores & these organisms are then consumed by another consumer or decomposed of when they die Carbon Cycle • • • • • Combustion Photosynthesis Respiration Decomposition Fossil fuels Steps of the Carbon Cycle CO2 in the air is used by producers for photosynthesis. They become part of the producers in the form of sugar. 2A. Respiration – most organisms (plants, animals, etc) breathe in O2 created by producers. They breathe out CO2. 2B. Combustion – burning of fossil fuels increase CO2 in the air. 2C. Decomposition – Decay of dead organic wastes by bacteria/fungi create CO2. 1. Nutrient Limitation Primary Productivity: rate at which organic material is produced by autotrophic organisms With ample sunlight & water, primary productivity may be limited by the nutrients available Limiting nutrient: nutrient whose supply limits productivity Limitations can occur in soil or in aquatic habitats