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99 Cards in this Set
- Front
- Back
Central Case Study: Vanishing Oysters of the Chesapeake Bay
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Chesapeake Bay was the world’s largest oyster fishery
Overharvesting, pollution, and habitat destruction ruined it The economy lost $4 billion from 1980 to 2010 Strict pollution standards and oyster restoration efforts give reason for hope |
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System
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a network of relationships among components that interact with and influence one another
Exchange of energy, matter, or information Receives inputs of energy, matter, or information; processes these inputs; and produces outputs |
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Feedback loop
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a circular process in which a system’s output serves as input to that same system
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Negative feedback loop
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output resulting from a system moving in one direction acts as an input that moves the system in the other direction
Input and output neutralize one another Stabilizes the system Example: if we get hot, we sweat and cool down Most systems in nature involve negative feedback loops |
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Positive feedback loop
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instead of stabilizing a system, it drives it further toward an extreme
Example: white glaciers reflect sunlight and keep surfaces cool Melting ice exposes dark soil, which absorbs sunlight Causes further warming and melting of more ice Runaway cycles of positive feedback are rare in nature But are common in natural systems altered by humans |
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Lithosphere
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rock and sediment
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Atmosphere
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the air surrounding the planet
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Hydrosphere
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all water on Earth
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Biosphere
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the planet’s living organisms
Plus the abiotic (nonliving) parts they interact with Categorizing systems allows humans to understand Earth’s complexity Most systems overlap |
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The Chesapeake Bay: a systems perspective
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The Chesapeake Bay and rivers that empty into it are an interacting system:
It receives very high levels of nitrogen and phosphorus from agriculture from 6 states, and air pollution from 15 states |
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Sources of nitrogen and phosphorus entering the Chesapeake Bay - watershed Definition
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Nitrogen and phosphorus enter the Chesapeake watershed (the land area that drains water into a river), causing….
Phytoplankton (microscopic algae and bacteria) to grow, then… Bacteria eat dead phytoplankton and wastes and deplete oxygen, causing… Fish and other aquatic organisms to flee or suffocate |
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Eutrophication
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the process of
Nutrient over enrichment, blooms of algae, increased production of organic matter, and ecosystem degradation |
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Eutrophication in aquatic systems
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Global hypoxic dead zones
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Nutrient pollution from farms, cities, and industries has led to more than 400 hypoxic (oxygen-depleted) dead zones
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People are changing the chemistry of Earth’s systems
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Chemistry is crucial for understanding how:
Chemicals affect the health of wildlife and people Pollutants cause acid precipitation Synthetic chemicals thin the ozone layer How gases contribute to global climate change |
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Matter
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all material in the universe that has mass and occupies space
It can be solid, liquid, or gas |
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Law of conservation of matter
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: matter can be transformed from one type of substance into others
But it cannot be destroyed or created Because the amount of matter stays constant It is recycled in nutrient cycles and ecosystems We cannot simply wish pollution and waste away |
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Element
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a fundamental type of matter
A chemical substance with a given set of properties Examples: nitrogen, phosphorus, oxygen 92 natural and 20 artificially created elements exist |
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Nutrients
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elements needed in large amounts by organisms
Examples: carbon, nitrogen, calcium |
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Atoms
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the smallest components that maintain an element’s chemical properties
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protons & neutrons
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The atom’s nucleus (center) has protons (positively charged particles) and neutrons (lacking electric charge)
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Atomic number
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the number of protons
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Electrons
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: negatively charged particles surrounding the nucleus
Balance the protons’ positive charge |
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The structure of an atom
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Isotopes
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atoms of an element with different numbers of neutrons
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Mass number
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the number of protons + neutrons
Isotopes of an element behave slightly differently |
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Ions
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atoms that gain or lose electrons
They are electrically charged |
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Radioactive isotopes
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Radioactive isotopes shed subatomic particles and emit high-energy radiation.
They decay until they become nonradioactive stable isotopes |
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Half-life:
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the amount of time it takes for one-half of the atoms in a radioisotope to give off radiation and decay
Different radioisotopes have different half-lives ranging from fractions of a second to billions of years Uranium-235, used in commercial nuclear power, has a half-life of 700 million years |
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Molecules and compounds
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An attraction for each other’s electrons bonds atoms
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Molecules
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combinations of two or more atoms
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Chemical formula
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indicates the type and number of atoms in the molecule (oxygen gas: O2)
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Compound
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: a molecule composed of atoms of two or more different elements
Water: two hydrogen atoms bonded to one oxygen atom: H2O |
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Carbon dioxide
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one carbon atom with two oxygen atoms: CO2
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Ionic bonds
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ions of different charges bind together
Table salt (NaCl): the Na+ ion is bound to the Cl– ion |
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Covalent bond
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atoms without electrical charges “share” electrons
Example: hydrogen atoms share electrons – H2 |
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Solutions
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electrons, molecules and compounds come together with no chemical bonding
Air contains O2, N2, H2O, CO2, methane (CH4), ozone (O3) Human blood, ocean water, plant sap, metal alloys |
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Hydrogen ions determine acidity
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Water can split into H+ and OH–
The pH scale quantifies the acidity or basicity of solutions Acidic solutions: pH < 7 Contain more H+ Basic solutions: pH > 7 Contain more OH– Neutral solutions: pH: 7 A pH of 6 contains 10 times as many H+ as a pH of 7 |
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Matter is composed of compounds
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Living things depend on organic compounds
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Organic compounds
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carbon atoms bonded together
They may include other elements: nitrogen, oxygen, sulfur, and phosphorus Carbon can be linked in elaborate chains, rings, other structures Forming millions of different organic compounds |
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Inorganic compounds
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lack the carbon–carbon bond
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Hydrocarbons
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organic compounds that contain only carbon and hydrogen
The simplest hydrocarbon is methane (natural gas) Fossil fuels consist of hydrocarbons Crude oil contains hundreds of types of hydrocarbons |
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Polymers
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long chains of repeated organic compounds
Play key roles as building blocks of life Three essential types of polymers: Proteins Nucleic acids Carbohydrates Lipids are not polymers, but are also essential Fats, oils, phospholipids, waxes, steroids |
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Macromolecules
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large-sized molecules essential to life
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Proteins are long chains of amino acids
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Proteins comprise most of an organism’s matter
They produce tissues, provide structural support, store energy, transport material Animals use proteins to generate skin, hair, muscles, and tendons Some are components of the immune system or hormones (chemical messengers) |
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enzymes
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They can serve as enzymes: molecules that promote (catalyze) chemical reactions
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Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
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carry hereditary information of organisms
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Nucleic acids
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long chains of nucleotides that contain sugar, phosphate,and a nitrogen base
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Genes
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regions of DNA that code for proteins that perform certain functions
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Carbohydrates
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: include simple sugars and large molecules of simple sugars bonded together
Glucose fuels cells and builds complex carbohydrates Plants store energy in starch, a complex carbohydrate Animals eat plants to get starch Organisms build structures from complex carbohydrates Chitin forms shells of insects and crustaceans Cellulose found in cell walls of plants |
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Lipids
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do not dissolve in water
Fats and oils (energy), waxes (structure), steroids |
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cells
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All living things are composed of cells: the most basic unit of organismal organization
Cells vary in size, shape, and function They are classified according to their structure |
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Eukaryotes
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plants, animals, fungi, protists
Contain a membrane-enclosed nucleus Their membrane-enclosed organelles do specific things |
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Prokaryotes
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bacteria and archaea
Single-celled, lacking membrane-enclosed nucleus and organelles |
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Energy
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an intangible phenomenon that can change the position, physical composition, temperature of matter
Involved in biological, chemical, physical processes |
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Potential energy
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energy of position
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Kinetic energy
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energy of motion
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Chemical energy
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potential energy held in the bonds between atoms
Changing potential into kinetic energy Releases energy Produces motion, action, or heat |
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Potential vs. kinetic energy
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Potential energy stored in our food becomes kinetic energy when we exercise and releases carbon dioxide, water, and heat as by-products
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First law of thermodynamics
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energy can change form but cannot be created or destroyed
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Second law of thermodynamics
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energy changes from a more-ordered to a less-ordered state
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Entropy
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an increasing state of disorder
Living organisms resist entropy by getting energy from food and photosynthesis Dead organisms get no energy and through decomposition lose their organized structure |
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The sun’s energy powers living systems
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Energy that powers Earth’s ecological systems comes mainly from the sun
The sun releases radiation from the electromagnetic spectrum Some is visible light |
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Autotrophs (producers)
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organisms that use the sun’s energy to produce their own food
Plants, algae, cyanobacteria |
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Photosynthesis ---- Will be on TEST
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the process of turning the sun’s light energy into high-quality chemical energy
Sunlight converts carbon dioxide and water into sugars Moving to lower entropy |
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Photosynthesis produces food
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Chloroplasts: organelles where photosynthesis occurs
Contain chlorophyll: a light-absorbing pigment Light reaction: solar energy splits water and creates high-energy molecules that fuel the … Calvin cycle: links carbon atoms from carbon dioxide into sugar (glucose) 6CO2 + 6H2O + sun’s energy C6H12O6 (sugar) + 6O2 |
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Cellular respiration releases energy
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It occurs in all living things (plants, animals, etc.)
Organisms use chemical energy created by photosynthesis Oxygen breaks the high-energy chemical glucose bonds The energy is used to make other chemical bonds or tasks |
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Heterotrophs
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organisms that gain energy by feeding on others
Animals, fungi, microbes The energy is used for cellular tasks C6H12O6 (sugar) + 6O2 ----->6CO2 + 6H2O + energy |
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Ecosystem
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all organisms and nonliving entities occurring and interacting in a particular area
Animals, plants, water, soil, nutrients, etc. Biological entities are tightly intertwined with the chemical and physical aspects of their environment For example, in the Chesapeake Bay estuary (a water body where fresh river water flows into salt ocean water): Organisms are affected by water, sediment, and nutrients from the water and land The chemical composition of the water is affected by organism photosynthesis, respiration, and decomposition |
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Energy and matter flow through ecosystems
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Sun energy flows in one direction through ecosystems
Energy is processed and transformed |
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Energy and matter flow through ecosystems
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Matter is recycled within ecosystems
Outputs: heat, water flow, and waste |
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Primary production
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conversion of solar energy to chemical energy in sugars by autotrophs during photosynthesis
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Gross primary production
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total amount of chemical energy produced by autotrophs
Most energy is used to power their own metabolism |
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Net primary production
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energy remaining after respiration
Equals gross primary production – cellular respiration It is used to generate biomass (leaves, stems, roots) Available for heterotrophs |
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Productivity
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rate at which autotrophs convert energy to biomass
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High net primary productivity:
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ecosystems whose plants rapidly convert solar energy to biomass
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A global map of net primary productivity
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NPP increases with temperature and precipitation on land, and with light and nutrients in aquatic ecosystems
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Ecosystems interact across landscapes
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Ecosystems vary greatly in size (puddle, forest, bay, etc.)
The term ecosystem is most often applied to self-contained systems of moderate geographic extent Adjacent ecosystems may interact extensively Ecotones: transitional zones between two ecosystems in which elements of each ecosystem mix It may help to view ecosystems on a larger geographic scale Encompassing multiple ecosystems Geographic information systems (GIS) use computer software to layer multiple types of data together |
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Landscape ecology & Patches
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the study of how landscape structure affects the abundance, distribution, and interaction of organisms
Useful for studying migrating birds, fish, mammals Helpful for planning sustainable regional development Patches: ecosystems, communities or habitat form the landscape and are distributed in complex patterns (a mosaic) This landscape consists of a mosaic of patches of 5 ecosystems |
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Conservation biologists
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study the loss, protection, and restoration of biodiversity
Humans are dividing habitat into small, isolated patches Corridors of habitat can link patches Populations of organisms have specific habitat requirements They occupy suitable patches of habitat in the landscape If a habitat is highly fragmented and isolated Organisms in patches may perish Conservation biologists may use corridors of habitat to link patches to preserve biodiversity |
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Model
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a simplified representation of a complicated natural process
Helps us understand processes and make predictions |
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Ecological modeling
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constructs and tests models to explain and predict how ecological systems work
Grounded in actual data and based on hypotheses Extremely useful in large, intricate systems that are hard to isolate and study Example: studying the flow of nutrients into the Chesapeake Bay and oyster responses to changing water conditions |
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Ecosystem services
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essential services provided by healthy, normally functioning ecosystems
When human activities damage ecosystems, we must devote resources to supply these services ourselves Example: if we kill off insect predators, farmers must use synthetic pesticides that harm people and wildlife All life on Earth (including humans) depends on healthy, functioning ecosystems One of the most important ecosystem services: Nutrients cycle through the environment in intricate ways |
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Ecological processes provide services
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Nutrient (biogeochemical) cycle
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Nutrients move through the environment in complex ways
Matter is continually circulated in an ecosystem Nutrient (biogeochemical) cycle: the movement of nutrients through ecosystems Pool (reservoir): a location where nutrients remain for varying amounts of time (residence time) Source: a reservoir releases more materials than it accepts Sink: a reservoir that are accepts more than it releases Flux: the rate at which materials move between reservoirs -Can change over time |
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Humans affect nutrient cycling
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Human activities affect nutrient cycling
Altering fluxes, residence times, and amounts of nutrients in reservoirs |
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The water cycle affects all other cycles
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Water is essential for biochemical reactions and is involved in nearly every environmental system and cycle
Hydrologic cycle: the flow of liquid, gaseous, and solid water through the environment Less than 1% is available as fresh water Evaporation: conversion of liquid to gaseous water Transpiration: release of water vapor by plants Precipitation: rain or snow returns water to Earth’s surface Runoff: water flows into streams, lakes, rivers, oceans |
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Water is also stored underground
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Infiltration: water soaks down through rock and soil to recharge aquifers
Aquifers: underground reservoirs of spongelike regions of rock and soil that hold … Groundwater: water found underground beneath layers of soil Water table: the uppermost level of groundwater held in an aquifer -Water in aquifers may be ancient (thousands of years old) |
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The hydrologic cycle
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Human impacts on the hydrologic cycle
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-Humans have affected almost every flux, reservoir, and residence time in the water cycle
-Damming rivers slows water movement and increases evaporation -Removal of vegetation increases runoff and erosion while decreasing infiltration and transpiration -Overdrawing surface and groundwater for agriculture, industry, and domestic uses lowers water tables -Emitting air pollutants that dissolve in water changes the nature of precipitation and decreases cleansing |
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Carbon cycle
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describes carbon’s route in the environment
-Carbon forms essential biological molecules -Through photosynthesis, producers move carbon from the air and water to organisms -Respiration returns carbon to the air and water -Oceans are the second largest reservoir of carbon Absorb carbon from the air, land, and organisms -Decomposition returns carbon to the sediment, the largest reservoir of carbon Ultimately, it may be converted into fossil fuels |
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Humans affect the carbon cycle
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Burning fossil fuels moves carbon from the ground to the air
-Since mid-1700s, people have added over 275 billion tons of carbon dioxide to the atmosphere Cutting forests and burning fields moves carbon from organisms to the air -Less carbon dioxide is removed by photosynthesis Today’s atmospheric carbon dioxide reservoir is the largest in the past 800,000 years -The driving force behind climate change |
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The nitrogen cycle involves bacteria
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Nitrogen makes up 78% of the atmosphere
It is contained in proteins, DNA, and RNA It is also essential for plant growth Nitrogen cycle: describes the routes of nitrogen through the environment Nitrogen gas is inert and cannot be used by organisms It needs lightning, bacteria, or human intervention to become biologically active and available to organisms Then it is a potent fertilizer |
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Nitrogen must become biologically available
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Nitrogen fixation: nitrogen-fixing soil bacteria or lightning “fixes” nitrogen gas into ammonium
Nitrogen-fixing bacteria live in legumes (e.g., soybeans) Nitrification: bacteria then convert ammonium ions first into nitrite ions then into nitrate ions Plants can take up these ions Nitrite and nitrate also come from the air or fertilizers Animals obtain nitrogen by eating plants or other animals Denitrifying bacteria: convert nitrates in soil or water to gaseous nitrogen, releasing it back into the atmosphere |
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Humans greatly affect the nitrogen cycle
Industrial fixation |
Historically, nitrogen fixation was a bottleneck: limited the flux of nitrogen from air into water-soluble forms
Industrial fixation fixes nitrogen on a massive scale Overwhelming nature’s denitrification abilities Excess nitrogen leads to hypoxia in coastal areas Nitrogen-based fertilizers strip the soil of other nutrients Reducing soil fertility Burning forests and fossil fuels leads to acid precipitation, adds greenhouse gases, and creates photochemical smog |
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Phosphorus cycle
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describes the routes that phosphorus takes through the environment
No significant atmospheric component Most phosphorus is in rocks With naturally low environmental concentrations, phosphorus is a limiting factor for plant growth Weathering releases phosphorus into water Allowing it to be taken up by plants Phosphorus is a key component of cell membranes, DNA, RNA, and other biochemical compounds |
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Humans affect the phosphorus cycle
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Fertilizer from lawns and farmlands
Increases phosphorus in soil Its runoff into water increases phytoplankton blooms and hypoxia Wastewater containing detergents releases phosphorus to waterways |
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Controlling nutrient pollution in waterways
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Reduce fertilizer use in farms and lawns
Change timing of fertilizer applications to minimize runoff Manage livestock manure applications to farmland Plant vegetation “buffers” around streams to trap runoff Restore wetlands and create artificial ones to filter runoff Improve sewage-treatment technologies Restore frequently flooded lands Reduce fossil fuel combustion |
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Conclusion
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Life interacts with its abiotic environment in ecosystems through which energy flows and materials are recycled
Understanding biogeochemical cycles is crucial -Humans are changing the ways those cycles function Understanding energy, energy flow, and chemistry increases our understanding of organisms -How environmental systems function Thinking in terms of systems can teach us how to: -Avoid disrupting Earth’s processes and to mitigate any disruptions we cause |