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Transcript
= is the study of organisms interacting with other organisms and their environment ◦It combines information from many different sciences is the portion of Earth that can support life ◦Many different environments exist in the biosphere ◦There are different parts that make up any environment: Biotic factors are all of the living parts Abiotic factors are all of the nonliving parts ex. temperature, soil, moisture, light, wind Organism is a living thing 2. Population is a group of organisms of one species that live in the same place at the same time and interbreed ◦ Members compete for food, water, mates, etc. 1. Community is a collection of interacting populations ◦ No population lives independently of other species 4. Ecosystem is the interactions among populations in a community and its physical surroundings 3. a. b. Terrestrial ecosystems are on land Aquatic ecosystems are in water = role a species plays in a community ◦The space, food, and other conditions an organism requires ◦How a species uses and affects its environment = where an organism lives out its life ◦Several species may share a similar habitat and its resources Autotrophs (also called producers) = organisms capable of making their own food 1. Heterotrophs (also called consumers) = organisms that obtain energy by consuming other organisms 2. Herbivores – “plant eaters” ◦ eat producers a. Carnivores – “meat eaters” ◦ eat other heterotrophs b. Omnivores ◦ eat both plants & animals d. Scavengers ◦ feed off dead or dying organisms e. Decomposers ◦ consume organic waste c. Energy constantly cycles through stable ecosystems A food chain is a model showing how energy moves through a portion of an ecosystem ◦Uses arrows to indicate the direction of energy flow grass rabbit hawk Has at least 3 links, but rarely more than 5 A portion of energy is lost at each link = model that shows all possible feeding relationships in a community ◦is a network of food chains Trophic levels include groups of organisms whose energy sources are the same number of steps from the sun Pyramids can be used to represent numbers and energy conversions within an ecosystem 1. 2. 3. The base of the pyramid = producers The 2nd level = herbivores and omnivores The 3rd level = carnivores and omnivores Only about 10% of the available energy is transferred to the next trophic level Symbiosis = close, long-term association between 2 or more species 1. parasitism = relationship where one organism benefits while harming another 2. mutualism = relationship where both species benefit 3. commensalism = relationship where one benefits and the other is unharmed Principles of population growth = the change in the size of a population with time 1. Speed of population growth ◦populations grow exponentially ◦this produces a J-shaped curve 2. Limiting factors keep a population from growing indefinitely ◦Density dependent factors = have an increasing effect as a population increases in size ◦Density independent factors = affect all of the population regardless of density The carrying capacity is reached when a particular environment cannot support any more organisms ◦produces an S-shaped curve 3. rapid life-history pattern ◦increase rapidly, then decline rapidly ◦organisms have: small body size, mature rapidly, reproduce early, have a short life span 1. slow life-history pattern ◦maintain pop. near the carrying capacity ◦organisms have: large bodies, mature and reproduce slowly 2. Predation ◦many predator-prey relationships show a cycle of pop. increases and decreases 1. Competition ◦small pops. have unlimited resources ◦large pops. have to compete fiercely for limited resources 2. Crowding and Stress ◦in large pops. individuals exhibit various symptoms that can lead to a pop. decrease 3. CO2 molecules are being produced by: ◦plant and animal respiration ◦decomposition ◦burning of fossil fuels CO2 molecules are being used during photosynthesis by plants Fill in the blanks with the following choices: burning CO2 gas decomposition photosynthesis respiration waste CO2 gas burning respiration photosynthesis decomposition waste demography = the study of population growth characteristics - the human population has been increasing exponentially over the past several hundred years Birth rate is the # of individuals born over a period of time Death rate is the # of individuals that die over a period of time Growth rate is the difference between the birth and death rates Fertility is the # of offspring a female produces during her reproductive years age structure is studied to make predictions of future populations the age structure shows whether a population is growing rapidly, slowly, or not at all migration = movement of individuals into or out of a population either type of movement affects national populations