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Transcript
Unit 2 Principals of Ecology Chapter 2 Section 2.1 Organisms and their relationshipos Ecology = the study of the interactive relationships of living things with their environment. A. Biosphere = the parts of the earth, oceans and air that are inhabited by organisms. (8 km deep in the ocean and 8 km high in the atmosphere) B. Biome = (Unit of the biosphere) group of ecosystems with the same type of climax communities. Can be classified as terrestrial or aquatic. C. Ecosystem = (unit of biosphere) Interaction of living and nonliving (wind, fire, climate, oxygen, carbon, etc.) things within a given environment Ex: forest An ecosystem can sustain itself by performing the following processes: 1. 2. 3. 4. produce chemical energy from the sun transfer energy decompose matter reuse nutrients (ex: nitrogen gas) An ecosystem can be large or small, but it is concerned with two types of environmental factors: 1. biotic factors - living organisms(plants & animals) 2. abiotic factors - nonliving parts (light & temperature, and water and soil) Organisms can move from one ecosystem to another (ex: a bird of prey) D. Communities = interacting communities make up an and ecosystem) A group of organisms that coexist with one another. (Ex: all of the organisms within a meadow) E. Population = (A community is made of interacting populations) A group of individuals of a single species that live together and share resources. Some communities have hundreds of populations like a coral reef. Some have only a few populations like a desert. F. Habitat = Surroundings in which any particular species can be found. The part of the ecosystem in which an organism lives. G. Niche = The role or way of life a species pursues within its habitat. (How much it eats, and what it eats, what its moisture requirements are, what temperature it requires or how much space it occupies) (You could think of a niche as an organism's occupation and its habitat as its address) Its total way of life. Level of organization from smallest to largest: Organism Population Community Ecosystem Biome Biosphere BIOTIC RELATIONSHIPS Competition and Predation Food, water and space are limited within an ecosystem and organisms compete for them constantly. 1. Competition = struggle for limited natural resources a. Intraspecific competition = b. Interspecific competition = competition between members of the same species. competition between members of one or more different species Competition resulted in the evolution of animals with distinct patterns of consumption . 2. Predation = One organism preying upon or eating another organism. Prey = heterotrophs consumed by predators SYMBIOSIS Symbiosis means "Living Together" A symbiotic relationship is a permanent , close relationship Between two organisms of different species that benefits at least one of them. 1. Mutualism = both organism benefit (ex: lichen [algae and fungi]) 2. Commensalism = one benefits, the other is unaffected (ex: Spanish moss on trees) 3. Parasiticism = one benefits at the expense of the other (ex: tick on a dog) Section 2.2 FLOW OF ENERGY WITHIN THE ECOSYSTEM Plants and algae are the chief producers. They are able to fix carbon as they convert solar energy into chemical energy in the form of food (glucose). This energy passes from one organism to another. Tropic Levels Various feeding levels of organisms. Organisms that are able to convert solar energy or inorganic compounds into chemical energy that can be used by the organism are called autotrophs. Organisms that cannot do this and rely on those autotrophs for food are called heterotrophs. Ex: plant, rabbit, bobcat Plants are the first or lowest trophic level in an ecosystem, and contain the most available energy. The tropic levels are: 1. 2. 3. 4. Primary Producer – Plants, algae (autotrophs) Primary Consumer - Plant eater (heterotroph) Secondary Consumer - Primary consumer eater Tertiary Consumer - Secondary consumer Ex: plant (1) – grasshopper (2) – mole (3) – bobcat (4) Consumers are classified according to what they eat 1. 2. 3. 4. 5. Herbivores – Carnivores – Omnivores – Scavenger – Decomposers – plant eaters meat eaters plant and animal eaters eats dead organisms breaks down dead plant and animal tissue and return the the nutrients to the soil. Food Chain A food chain is the pathway of food through the ecosystem. i.e., one organism feeding on another) Food Web Network of interacting food chains) Ecosystems have more than one food chain. Chains overlap because organisms eat more than one type of food. (See page 43, Glencoe) Ecological Pyramids The energy available for use by organisms at each trophic level is only about 10% of the preceding level. Ex: Plant gets energy from the sun (uses some of the energy for q food making and metabolism - about 90%.) Rabbit eats the plant (gets only about 10% of what the plant did.) Bobcat eats the rabbit (gets only about 10% of what the rabbit gets.) Use of Ecological Pyramids Ecological Pyramids are diagrams used to show a decrease of available energy in the ecosystem. Ex: energy pyramid or pyramid of biomass (See pages 44 Glencoe) Biomass = weight of an organism after all of the water is removed Section 2.3 Cycling of Matter The major elements needed for life are: carbon, hydrogen, oxygen and nitrogen. ** Other chemical requirements include sulfur, phosphorus and various other trace elements. When death occurs, these chemical materials are returned to the earth and atmosphere. This is RECYCLING. MAJOR CYCLES: A. Water Cycle 1. 2. 3. 4. 5. the sun evaporates water from the oceans, lakes, streams, etc. water is lost through the stomata of plants via transpiration water seeps from soil to underground springs, streams and rivers water molecules are carried to the atmosphere via wind or air currents water droplets condense around dust and are returned to the atmosphere as rain, snow, hail or fog. B. Oxygen/Carbon Cycles Without carbon molecules, life could not exist. 1. carbon and oxygen make up most of the body's carbohydrates, proteins and fats and are also involved in the majority of chemical reactions. 2. 3. These cycles are driven by photosynthesis and respiration: (i.e., autotrophs such as plants, algae and photosynthetic bacteria take in carbon dioxide and release oxygen as they fix carbon to make glucose [food]. As food is metabolized by heterotrophs such as animals, fungi, bacteria and protozoa, oxygen is taken in and the unused carbon from above is released as carbon dioxide in the air or as solid waste. Decomposers break down these wastes and dead tissue which releases more carbon dioxide into the air.) In addition to the above, carbon is recycled during the burning of fossil fuels. Oxygen Cycle Carbon Cycle C. Nitrogen Cycle Proteins and DNA have nitrogen within them. 78 percent of the air is nitrogen gas but it is useless to plants in this gaseous form. Nitrogen must be used as n i t r a t e s , n i t r i t e s o r a m m o n i a . Nitrogen fixation = conversion of nitrogen gas (N2) into nitrate (N03-) Nitrogen fixing bacteria found in the roots of legumes fix nitrogen gas into nitrates for plants to use. When plants and animals excrete waste or die, bacteria convert nitrogen into ammonia. This is called AMMONIFICATION. Plants cannot use ammonia, so bacteria convert it into Nitrite (NITRIFICATION) This is a twostep process. ** some bacteria convert ammonia into nitrite then others convert nitrites into nitrates. Some bacteria convert ammonia, nitrite and nitrates back into nitrogen gas. (DENITRIFICATION). This returns nitrogen gas to the atmosphere. D. Phosphorus Cycle Phosphorus is essential for growth and development of organism Phosphorus is in ATP, DNA, RNA, Short term and long term cycles. Short term: SoilProducersconsumers, when organisms die or produce waste decomposers return phosphorus to soil. Long term: Weathering of rock and soil that contains phosphorus will slowly add phosphorus to the soil.