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AP Biology Chapter 42
Terms in this set (35)
what is an ecosystem?
ecosystems are the sum of all organisms living in a given area and the abiotic factors with which they interact.
where does energy enter most ecosystems? how is it converted to chemical energy and then passed through the ecosystem? how is it lost?
energy enters most ecosystems as sunlight. this sunlight is converted to chemical energy by autotrophs, passed to heterotrophs in the organic compounds of food, and dissipated as heat. it is lost as heat energy from the heterotrophs.
besides the energy flow that you described in question 2, chemicals such as carbon and nitrogen cycle through ecosystems. so energy ______ through an ecosystem and matter __________.
2. cycles within ad throughout ecosystems
both energy and matter can be neither _______ nor _______.
what trophic level supports all others?
primary producers support the other trophic levels.
list three groups of organisms that are photosynthetic autotrophs.
plants, algae, and photosynthetic prokaryotes are photosynthetic autotrophs
what are the primary producers of the deep-sea vents?
chemosynthetic prokaryotes are the primary producers of deep sea vents.
what are the trophic levels? what is always the first trophic level?
trophic levels are any class of organisms that occupy the same position and function in a food chain. primary producers are always the first trophic level.
what are detritivores? what is their importance in chemical cycling?
detritivores are consumers that derive their energy and nutrients from nonliving organic materials such as corpses, fallen plant material and the wastes of living organisms. detritivores convert organic matter from all trophic levels to inorganic compounds usable by primary producers, closing the loop in chemical cycling. organisms such as fungi and prokaryotes.
what is primary production? distinguish between gross primary production and net primary production?
primary production is the amount of light energy converted to chemical energy (organic compounds) by the autotrophs in an ecosystem during a given time period. gross primary production is the total primary production of an ecosystem while the net primary production is the GPP minus the energy used by the producers for respiration.
write an equation here that shows the relationship between gross and net primary productions.
total mass of all individuals in a trophic level.
why is net primary production, or the amount of new biomass/unit of time, the key measurement to ecologists?
NPP is the key measurement to ecologists because it represents the storage of chemical energy that will be available to consumers in the ecosystem.
which ecosystem would tend to have a greater biomass/unit area a prairie or a tropical rain forest?
a prairie would not accumulate as much as biomass as a forest because the animals consume the plants rapidly and because grasses and herbs decompose more quickly.
describe a technique for measuring net primary production in an aquatic environment.
satellites provided a powerful tool for studying global patterns of primary production. images produced from satellite data show that different 'ecosystems vary considerably in their NPP. the presence of chlorophyll is used to determine the rate of photosynthesis and in different regions of the globe. chlorophyll captures visible light and photosynthetic organisms absorb more light at visible wavelengths than at near infrared wave lengths. scientists use this different in absorption to estimate the rate of photosynthesis in different regions of the globe using satellites.
what are some factors that limit primary productivity in aquatic ecosystems?
the depth of light penetration and nutrients can limit primary production in aquatic ecosystems.
what is limiting a limiting nutrient? what is limiting nutrient off the shore of long island, new york? in the sargasso sea?
a limiting nutrient is the element that must be added for production to increase. nitrogen is the limiting nutrient off the shore of long island, new york. iron is the limiting nutrient in the sargasso sea.
phytoplankton growth can be increased by additional nitrates and phosphate. what are common sources of each of these?
septic systems, animal feed lots, agricultural fertilizer manure, industrial waste waters, sanitary land fills, and garbage dumps are common sources of nitrates. animal waste, phosphorous rich bedrock, laundry, cleaning industrial wastes, and fertilizer runoff are the sources of phosphates.
what is eutrophication? what are the factors that contribute to eutrophication
eutrophication is a process by which nutrients particularly phosphorous and nitrogen become highly concentrated in a body of water, leading to increased growth go organisms such as algae or cyanobacteria. sewage and fertilizer run off as well as the death of primary producers can contribute to eutrophication.
what is trophic efficiency?
trophic efficiency is the percentage of production transferred from on trophic level to the next.
generally, what percentage of energy available at one trophic level is available at the next?
typically, only 10% of energy at one trophic level is available at the next.
consider a food chain with 1,000 joules available at the producer level. if this food chain is grass —> grasshopper—> lizard —> crow, how much energy is found at the level of the crow.
1,000J x .1= 100J x .1= 10J x .1=1J
label the trophic levels on both figures below. explain why the second pyramid of biomass is inverted.
inverted biomass pyramids occur because the producers grow, reproduce, and are consumed by the primary consumers so quickly that they never develop a large population size.
see figures in question 23.
why do people who have limited diets in overpopulated parts of the world eat low on the food chain?
they eat this way because it is more efficient to eat as primary consumers. we can tap into photosynthetic production by eating this way. eating meat is inefficient and we could feed many more people by eating lower on the food chain.
use the following figure to describe the water cycle. specify the roles of evaporation, transpiration, and rainfall.
the water cycle is important because it influences the rates of ecosystem processes especially primary production and decomposition. the evaporation of liquid water by solar energy and precipitation are two of main process driving the water cycle. transpiration moves large volumes of water into the atmosphere.
use figure 42.13 to describe the water cycle. in doing so, explain how carbon enters the living system and how it leaves, indicate the role of microorganisms in the cycle, and identify the reservoir for carbon.
photosynthesis organisms use CO2 during photosynthesis and convert the carbon to organic forms used by consumers, including animals, fungi, heterotrophic protists, and prokaryotes. carbon enters the atmosphere through the burning of fossil fuels and cellar respiration of animals. it leaves the atmosphere through photosynthetic and works it's way down the food chain until an animal dies. it decomposes and eventually becomes fossil fuels that are burned. the major reservoirs of carbon are fossil fuels, soils, sediments of aquatic ecosystems, the oceans, plant and animal biomass, and the atmosphere. the largest reservoir is sedimentary rock. photosynthesis removes substantial amounts of CO2 each year.
use the following diagram to describe the nitrogen cycle. in doing so, indicate the role of microorganisms in nitrogen fixation, nitrification, and denitrification.
nitrogen fixation is the conversion of N2 forms that can be used synthesize organic nitrogen compounds certain bacteria can fix nitrogen naturally. some bacteria carry out denitrification, the reduction of nitrate to nitrogen gases. nitrifying bacteria can also oxidize ammonia or ammonium to nitrate followed by the oxidation of nitrite to nitrate.
review the case study: nutrient cycling in the hubbard brook experimental forest. what effect has deforestation been shown to have on chemical cycling.
the amount of nutrients leaving an intact forest ecosystem is controlled mainly by the plants. during the study it showed that the water runoff from the newly deforested water shed was 30-40% greater because there were no plants to absorb and transpire water. both water and plants are important in chemical cycling.
what is the goal of restoration ecology?
restoration ecologists work to identify and manipulate the processes that most limit the resources of ecosystems from disturbances.
uses organisms- usually prokaryotes, fungi, or plants-to detoxify polluted ecosystems.
uses organisms to add essential materials to a degraded ecosystems.
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