AP Environmental Science Unit 1-2 The Living World

AP Environmental Science Study Guide Unit 1-2: The Living World ● Ecosystem Structure ○ Abiotic vs. Biotic Components ■ Abiotic ● Nonliving components of Earth ○ Eg: Atmosphere, Hydrosphere, and Lithosphere ■ Biotic ● Living components of Earth ○ Eg: Animals, plants, fungi, protists, and bacteria which form the biosphere ○ Interactions of Organisms with the Environment ■ Population ● A group of organisms of the same species ■ Community ● Populations of different species that occupy the same geographic area ● Every species occupies a habitat and has an ecological niche ■ Habitat ● The area or environment where an organism lives, or where an ecological community occurs ■ Ecological Niche ● The role and position a species has in its environment ● Includes how a species uses biotic and abiotic resources in its environment, where the species lives, and what it eats ○ Interactions of Organisms Among Each Other ■ Competition ● Occurs when two individuals are competing for resources in the environment ■ Resource Partitioning ● Occurs when species can coexist and share resources without any conflict ■ Predation ● Occurs when one species feeds on another ● Drives changes in population size ○ Eg: ■ Cat & Mouse ■ Polar Bear & Seals ■ Lions & Wildebeests ■ Great White Shark & Elephant Seals ○ Symbiotic Relationships ○ Close, prolonged associations between two or more different organisms of different species ■ Types of Symbiotic Relationships ● Mutualism ○ Both organisms receive beneficial properties from their relationship ■ Eg: pollinators benefit from feeding on plant nectar, and plants benefit from pollinators moving their pollen from plant to plant ● Commensalism ○ One organism benefits in the relationship and the other are neither harmed nor benefited ■ Eg: Barnacles are sedentary crustaceans that sweep the surrounding water for small, free-floating organisms. They often grow attached to scallop shells, which has almost no effect on the scallop ● Parasitism ○ One organism benefits by harming the other organism ■ Eg: Mistletoe is a flowering plant that grows attached to, and within, the vascular system of a tree or shrub. This helps the mistletoe but harms the tree ● Types of Ecosystems ○ Classifications ■ Blending ● The biomes blend into each other ● There are no distinct boundaries ■ Ecotones ● A transitional area where two biomes meet ■ Ecozones/Ecoregions ● Small regions within ecosystems that have similar physical features ■ Edge Effects ● Ecotones have a great amount of species diversity and biological density ● Some species only live on the edge of certain habitats ● Energy Flow ○ Cell Respiration - Occurs when autotrophs make ATP (adenosine triphosphate) from carbohydrates and other biomolecules in a complex series of reactions ○ Bioenergetics - The study of how energy flows through living organisms ■ All energy on Earth comes from the Sun ■ Photosynthetic organisms use solar energy to turn CO2 and H2O into carbohydrates ● Also releases O2 ■ Biological macromolecules store energy in their chemical bonds ■ Cells use respiration to transfer energy from the chemical bonds of macromolecules to the chemical bonds of smaller molecules like ATP, GTP, NADH, NADPH and FADH2 ● This releases CO2 and H2O ■ These small, high-energy molecules power all the reactions and processes the cell needs to perform ○ Photosynthesis ● Plants and algae are producers and perform photosynthesis: they convert solar energy into chemical energy ● In plants, most photosynthesis occurs in leaves ● Algae include some bacteria and plant-like protists ■ Light-Dependent Reactions ● Purpose: ○ Convert light energy to chemical energy ○ Reactant(s) = Sunlight + H2O ○ Products(s) = O2 + ATP + NADPH ■ Light-Independent Reactions ● Purpose: ○ Use ATP and NADPH to build organic molecules from CO2 ○ Reactant(s) = CO2 + ATP + NADPH ○ Product(s) = C6H12O6 ○ Cellular Respiration ● All living organisms require a source of energy, and all living organisms use the same metabolic pathways to power life ● Cell respiration is a series of redox reactions. Glucose is oxidized to CO2, and this powers the synthesis of ATP, an energy source ● All living organisms perform cellular respiration ● Classifying Organisms in Ecosystems ○ Autotrophs ■ Autotrophs produce complex organic compounds from simple substances in the environment ■ Most autotrophs use energy from light (photoautotrophs) ■ Some autotrophs use inorganic chemical reactions instead ■ Autotrophs serve as primary producers in a food chain ■ Example: ● Producers ● Saprotrophs ○ Heterotrophs ■ Heterotrophs consume other organisms in a food chain ■ A heterotroph is unable to produce organic substances from inorganic ones ■ Heterotrophs depend either directly or indirectly on autotrophs for nutrients and food energy ■ Example: ● Primary Consumers ● Secondary Consumers ● Tertiary Consumers ● Decomposers ● Detritivores ● Food Chains & Food Webs ○ Food Chain - shows how energy flow step by step from producer to consumers ■ Eg. ● Rice→Humans→Microorganisms ● Corn plants→Beef cattle→Humans ● Phytoplankton→Crustaceans→Fish→Humans ○ Energy Pyramid - shows how much energy is available to each successive trophic level ○ Food Webs - show the complex interactions between many species ● Ecosystem Diversity - describes how variable an ecosystem is within a geographical location ○ Biodiversity ● The number and variety of organisms found in the world or in a particular habitat or ecosystem ● The variability among living organisms ● Biodiversity in all forms is the result evolution ● More biodiversity means a larger and more diverse gene pool, which leads to a greater chance of adaptation and survival ○ Evolution - the change in the population’s genetic composition over time ■ Natural Selection ● The natural selection of advantageous traits changes the makeup of a population ○ Charles Darwin (Father of Evolution) Theory ■ Certain organisms live and reproduce, and other die ■ Beneficial inherited characteristics are passed down to the next generation ■ Unfavorable heritable characteristics become less common in the population ■ This process acts upon a whole population over time, not on one individual organism ■ Genetic Drift ● Chance events change the makeup of a population with no regard to traits ■ Phylogenetic Tree - a diagram that shows how organisms are related based on evolutionary relationships. ○ Species - a group of organisms that are capable of breeding with one another but incapable of breeding with other species ■ Speciation - the formation of new species from preexisting species ○ Extinction - occurs when a species cannot adapt quickly enough to environmental change and all members of the species die ■ Biological Extinction ● Extermination of a species ● No individuals of this species left on the planet ○ Eg: Dodo birds, Passenger pigeon, Mammoth, Dinosaurs ■ Ecological Extinction ● So few individuals of a species that this species can no longer perform its ecological function ○ Eg: Alligators in the Everglades in 1960; Wolves in Yellowstone before reintroduction in the 1990s ■ Commercial or Economic Extinction ● A few individuals exist, but the effort needed to locate and harvest them is not worth the expense ○ Eg: Groundfish population of the Grand Banks ● Ecosystem Services ■ Humans gain many benefits from the natural environment and from properly functioning ecosystems ■ Ecosystems are essential to life ■ Land, water, and air must be used responsibly if they are to benefit future generations ○ Provisioning Services ■ Physical items we obtain from our environment ■ Example: ● Food ● Raw materials ● Water ● Energy ● Medicinal resources ■ Cultural Services ● Non-material benefits people obtain from the ecosystem ● Example: ○ Recreation ○ Science & education ○ Tourism ○ Inspiration for culture & art ○ Spiritual experience ■ Regulating Services ● Benefits obtained from the regulating of ecosystems. These are often hard to see and are taken for granted ● Example: ○ Pest & disease control ○ Water & air purification ○ Climate regulation ○ Waste decomposition & detoxification ○ Pollination ■ Support Services ● Allow for other ecosystems services to be present ○ Example: ■ Nutrient recycling and soil formation ● Natural Ecosystem Change ○ Types of Species ■ Keystone ● Maintain the biotic balance in a community ● Their presence contributes to an ecosystem’s diversity ● Their extinction would lead to a large change in the ecosystem ○ Eg: Fig trees in a tropical forest; Wolves in western North America ■ Indicator ● Used as a standard to evaluate the health of an ecosystem ● More sensitive to biological changes within their ecosystems than others species ● Used as an early warning system to detect dangerous changes to a community ○ Eg: Trout in freshwater biomes ○ Ecological Succession ■ Primary Succession ● Begins in a virtually lifeless area, such as the area below a retreating glacier ■ Secondary Succession ● Takes place where an existing community has been cleared, but the soil has been left intact ■ Pioneer Species ● Organisms present in the first stages of either type of succession ● Have wide ranges of environmental tolerance ■ Climax Community ● Formed in the final stage of succession ● Have a dynamic balance between abiotic and biotic components of the community ■ Habitat Fragmentation ● When a natural habitat is reduced or fragmented ● When a regular and balanced ecosystem is damaged