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Energy Flow Through an Ecosystem Food Chains, Food Webs, Energy Pyramids BIO.B.4.2.1 Describe how energy flows through an ecosystem (e.g. food chains, food webs, energy pyramids) •Begins with the SUN •Photosynthesis 6CO2 + 6H2O + sunlight & chlorophyll C6H12O6 + 6O2 • The chemical reaction by which green plants use water and carbon dioxide and light from the sun to make glucose. • ENERGY is stored in glucose; glucose is stored as starch. Organisms that can make glucose during photosynthesis are called PRODUCERS or AUTOTROPHS. Producers use most of the energy they make for themselves. Producers use cellular respiration to supply the energy they need to live. 6O2 + C6H12O6 --> 6H2O + 6CO2 + energy CELLULAR RESPIRATION is the chemical reaction that releases the energy in glucose. The energy that is not used by producers can be passed on to organisms that cannot make their own energy. Self-Sustained Ecosystems Organisms that cannot make their own energy are called CONSUMERS or HETEROTROPHS. Types of Heterotrophs • Saprophytes: plants, fungi and bacteria which live on dead matter (AKA = decomposers). • Herbivores : plant-eating animals • Carnivores: meat-eating animals • Types of Carnivores » Predators – animals which kill and consume their prey » Scavengers – those animals that feed on other animals that they have NOT killed. • Omnivores: plant AND meat eaters Trophic Levels Trophic Levels = locations within a food chain: • Primary producers: photosynthetic organisms (plants, algae, some bacteria) • Primary consumers: consume primary producers • Secondary consumers: consume primary consumers • Tertiary consumers: consume secondary consumers Energy flows through ecosystems in one direction, typically from the sun, through photosynthetic organisms, including green plants and algae, through herbivores, to carnivores and finally decomposers. SUN PHOTOSYNTHETIC ORGANISMS HERBIVORES CARNIVORES DECOMPOSERS Trophic Level Nutrition • Autotrophic nutrition – Photosynthesis (from CO2 & H2O) • Heterotrophic nutrition – Respiration (from eating food) Most of the energy passed from one consumer to the next is used by the consumer. Some of the energy is lost and moves into the atmosphere as heat. Some energy is stored and can be passed on to another consumer. Food Chains and Food Webs • If an ecosystem is to be self-sustaining it must contain a flow of energy. • The pathways of energy through the living components of an ecosystem are represented by food chains and food webs. • Producers initiate the flow of energy by converting solar energy (sunlight) into the chemical energy (ATP) from food. A food chain involves the transfer of energy from green plants through a series of organisms with repeated stages of eating and being eaten. Food Webs: • A group of interconnected food chains • They show the feeding relationships in an ecosystem Energy Transfer Is Also Modeled Through Pyramids •Energy Pyramids – indicates the amount of energy transferred to each trophic level •Biomass Pyramids – indicates the total mass for all species at each trophic level •Pyramid of Numbers – indicates the number of organisms at each level Energy Pyramids • • • • • • An Energy Pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food web or food chain. Energy Pyramid only 10% of the energy available within one trophic level is transferred to organisms at the next trophic level. There is much more energy in the producer level of a food chain than at the consumer levels. Energy input usually = SUN. Only 10% of the energy from the sun is captured by producers. Only 10% of the energy available in producers is transferred to consumers Biomass Pyramid Pyramid of Numbers Which One???? • Shows an ecosystem containing one tree, many herbivores, many omnivores, and one carnivore (eagle)? Biotic Interactions In An Ecosystem Symbiotic Relationships BIO.B.4.2.2 – Describe biotic interactions in an ecosystem (eg., competition, predation, symbiosis) Symbiotic Relationships • Symbiotic relationship = relationship between two organisms • Types of Symbiotic Relationships 1. Mutualism 2. Parasitism 3. Commensalism MUTUALISM PARASITISM COMMENSALISM Mutualism • Mutualism – a type of symbiotic relationship in which both organisms benefit • Examples: – Oxpecker feeds on the ticks of rhinos. – Acidophilus bacteria in the human digestive tract. Bacteria get nutrients from the human and the human digestive process is assisted. Parasitism • Parasitism – a type of symbiotic relationship in which one organism benefits and the other is harmed • Examples: – A tick feeds off a deer’s blood. – A tapeworm feeds off a human stripping it off valuable nutrients. Commensalism • Commensalism – a type of symbiotic relationship in which one organism benefits and the other organism does not benefit or is not harmed. • Examples: – Hermit crab lives in a snail shell. – Barnacles attach themselves to whales. Habitat vs. Niche • Habitat: an area that provides an organism with its basic needs for survival. (Like food, shelter, temperature, moisture, etc...) • Niche: the role an organism plays in its ecosystem (aka - an organisms job) • An organisms location in a food chain helps to determine its niche. • An organisms structure or shape determines its function which influences its niche. • Fitness: a measure of an organisms health as determined by its ability to produce offspring (a measure of population size) Competition • Competition: occurs when two different species or organisms living in the same environment (habitat) and use the same limited resources such as: »Food »Water »Space »Light »Minerals Competition • Competition reduces fitness (population size) of one or both species. • Types of competition: – Intraspecific competition Competition between members of the same species – Interspecific competition Competition between members of different species • The more similar the requirements of the organisms involved, the more intense the competition. • Two organisms can share the same HABITAT but not occupy the same NICHE! Predator-Prey Relationships • Predation: one species feeds on another • Predation will improve the fitness of the predator, but reduces the fitness of the prey. Ecological Roles • Specialist: organism that eats a particular type of food and/or lives in a specific environment (small range) • Examples: – Koalas – Cactus – Giraffes • Generalist: organism that eats many types of food or lives in a wide range of environments • Keystone Species: a species that is at the center of a food web and has an unusually large impact on its ecosystem – American Alligator: makes “alligator holes” in the Everglades that serve as a source of food and water for other animals during droughts Recycling Matter in Ecosystems Water Cycle, Carbon Cycle, Oxygen Cycle And Nitrogen Cycle BIO.B.4.2.3 – Describe how matter recycles through an ecosystem (ie. Water cycle, carbon cycle, oxygen cycle, and nitrogen cycle) Recycling Matter • In a self-sustaining ecosystem, materials must be cycled between organisms and the abiotic environment…this is where processes like photosynthesis and cellular respiration play important roles. • Materials constantly need to be recycled from the living and non-living environment so that materials can be reused by different living organisms in order to maintain biogeochemical cycles and hydrologic cycles like the water cycle, oxygen cycle, carbon cycle and nitrogen cycle.. Water Cycle Involves the following processes: •Precipitation •Evaporation •Condensation •Transpiration Water Cycle Terminology • Evaporation – water separates into hydrogen and oxygen molecules due to a rise in temperature • Condensation – water collects due to a drop in temperature • Precipitation – water falls from the clouds due to changes in temperature and pressure • Surface Water and Groundwater – water collects or runs from one region to another • Transpiration – plants draw water up from the ground and release it through their stoma (openings) in the leaves Carbon Cycle Carbon is added to the atmosphere (CO2) by the following: •Combustion - Burning of Fossil Fuels (exhaust) •Respiration – From ALL organisms, aquatic and terrestrial •Natural Events – Volcanism Carbon is removed from the atmosphere (CO2) by the following: •Photosynthesis – From aquatic and terrestrial organisms Carbon is transferred between the earth and living organisms by: •Consumption - Carbon is transferred from plants to animals through organic molecules like carbs, lipids and proteins. In other words….Carbon passes through food chains and food webs as one organism consumes the next. •Decomposition – Carbon molecules from dead organisms form fossil fuels. Carbon Cycle Oxygen Cycle • • • Oxygen is added to the atmosphere by the following: – Photosynthesis - From aquatic and terrestrial organisms Oxygen is removed from the atmosphere: – Respiration - From ALL organisms, aquatic and terrestrial – Decomposition – Oxygen is needed to allow this process to continue – Combustion – Oxygen is required to fuel the fire! Oxygen is also found in organic compounds in living things: – Carbohydrates – Lipids (Fats) – Proteins Oxygen Cycle Nitrogen Cycle • • • • • • • All life requires nitrogen-compounds like amino acids, proteins & nucleic acids. The majority of nitrogen, 79%, is supplied by the air, but the nitrogen in the air is not a usable form for most organisms. Nitrogen fixation = process of bacteria converting nitrogen gas (N2) into usable nitrogen compounds. Usable forms of nitrogen include: – Nitrates (NO3-) – Nitrites (NO2-) – Ammonia (NH3) Different types of bacteria help us convert nitrogen into different forms: – Nitrification = converts ammonia into nitrites OR nitrites into nitrates – Denitrification = converts nitrates back into nitrogen gas Plants get usable nitrogen compounds from nitrogen fixing bacteria. Animals get their nitrogen by consuming plants. Decomposing plant and animal matter supplies a source of nitrogen. Nitrogen fixing Animal waste also provided a source bacteria forming of nitrogen. root nodules on legumes. Nitrogen Cycle Nitrogen Gas Ammonia Nitrates/Nitrites Nitrogen Gas A B C A = Nitrogen Fixation B = Nitrification C = Denitrification