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Ch. 3 The Biosphere
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3-1 What Is Ecology? Ecology- the study of interactions among organisms and between organisms and their environment.
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3-1 What Is Ecology? Biosphere- the combined portions of the planet in which all life exists, including land, water and air.
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3-1 What Is Ecology? To understand relationships within the biosphere, ecologists study events and organisms that range from a single individual to the entire biosphere.
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3-1 What Is Ecology? Species- organisms so similar that they can breed and produce fertile offspring. Populations- one species that lives in the same area. Communities- many different species that live in the same area.
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3-1 What Is Ecology? Ecosystem- all the organisms in a particular place together with their nonliving environment. Biome- group of ecosystems that have the same climate and similar communities.
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3-1 What Is Ecology? Scientists conduct ecological research using three basic approaches: 1) observing 2) experimenting 3) modeling
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3-2 Energy Flow Sunlight is the main energy source for life on Earth.
Some types of organisms can use the energy stored in inorganic chemical compounds.
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3-2 Energy Flow Autotrophs(producers)- use energy from the environment to make their own food. Photosynthesis- the process of converting light energy into carbohydrates (food).
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3-2 Energy Flow Chemosynthesis- the process of using chemical energy to produce carbohydrates (food).
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3-2 Energy Flow Heterotrophs(consumers)- organisms that rely on others for their energy and food supply. Herbivores- plant eaters Carnivores- meat eaters Omnivores- plant and meat eaters Detritivores- eat dead matter (plant and animal remains)
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3-2 Energy Flow Decomposers- bacteria and fungi that break down organic matter. Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs and then to heterotrophs.
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3-2 Energy Flow Food chain- a series of steps in which organisms transfer energy by eating and being eaten. Food web- complex interactions linking various food chains in an ecosystem together.
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3-2 Energy Flow Trophic level- one level in a food chain or food web (1st trophic level-producers, 2nd trophic level- consumers, etc.) Ecological pyramid- shows the relative amounts of energy or matter within each trophic level.
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3-2 Energy Flow Only about 10% of the energy available within one trophic level is transferred to organisms at the next trophic level! Biomass- total amount of living tissue within a given trophic level.
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3-3 Cycles of Matter Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Biogeochemical cycles- elements, compounds and other matter passed between organisms in different parts of the biosphere.
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3-3 Cycles of Matter The Water Cycle
Evaporation- process by which water changes from liquid to gas. Transpiration- water evaporating from the leaves of plants.
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3-3 Cycles of Matter Nutrients- all the chemical substances that an organism needs to sustain life. All living organisms need nutrients to build tissues and carry out essential life functions.
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3-3 Cycles of Matter Nitrogen fixation- process by which certain bacteria convert atmospheric nitrogen into ammonia, nitrates, and nitrites to be used by producers to make proteins. Denitrification- process by which some soil bacteria convert nitrates into nitrogen gas.
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3-3 Cycles of Matter Primary productivity- the rate at which producers can create organic matter. Limiting nutrient- substance that is scarce or cycles slowly, limiting an ecosystem.
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3-3 Cycles of Matter Algal bloom- a large increase in algae and other producers when an aquatic ecosystem receives a large amount of a limiting nutrient (i.e., runoff from heavily fertilized field).
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