APES FINAL EXAM STUDY SET

**La Niña

"Normal" year, easterly trade winds and ocean currents pool warm water in the western Pacific, allowing upwelling of nutrient rich water off the West coast of South America.

**Transitional stage

(demographic transition) death rate lower, better health care, population grows fast

Traveling southward from the Arctic regions of Canada to the tropics of Panama, one passes through several biomes - tundra, coniferous forest, temperate deciduous forest, and tropical rain forest. This pattern of change in vegetation is primarily the result of...

...an increase in both mean annual temperature and mean annual precipitation

Most of the Earth's deserts are at approximately 30° latitude, north and south, because these latitudes are characterized by...

...descending dry air currents

Surface oceanic circulation results most directly in the...

...distribution of heat from tropical to temperate and polar regions

The annual fluctuation in carbon dioxide concentration can best be explained by the...

...seasonal photosynthetic activity of green plants

Small populations of animals, such as those typically found on islands, are prone to extinction because...

...they are more vulnerable to unpredictable events

The polar regions radiate away more heat energy than they receive from the Sun in the course of a year. However, they are prevented from becoming progressively colder each year primarily by the...

...transport of heat through the atmosphere and oceans

The net annual primary productivity of a particular wetland ecosystem is found to be 8,000 kcal/m2 per year. If respiration by the aquatic producers is 12,000 kcal/m2 per year, what is the gross annual primary productivity for this ecosystem, in kcal/m2 per year?

20,000

A temperate grassland biome has a gross primary productivity of 3,480kilocalories/meter2/year and a net primary productivity of 2,000kilocalories/meter2/year. Which of the following is the approximate number of kilocalories/meter2/year available to herbivores in that biome?

200kilocalories/meter2/year

A country currently has a population of 100 million and an annual growth rate of 3.5 percent. If the growth rate remains constant, what will be the population of this country in 40 years?

400 million

Which of the following is a direct economic consequence that would likely occur if an area of forest was clear-cut so that a housing development can be built?

A decrease in the number of game hunting licenses purchased

The Atlantic Ocean is expanding as a result of plate tectonics. Which of the following explanations best identifies the type of plate boundary and processes occurring at the Mid-Atlantic Ridge, as shown in the diagram below?

A divergent plate boundary exists at the Mid-Atlantic Ridge where plates move away from one another, leading to seafloor spreading.

A variety of plants and animals inhabit a forest ecosystem. Which statement correctly explains why certain organisms would be more likely to survive than others if a forest fire burned the area?

A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources. A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet. Loss of habitat leads to a loss of specialist species before a loss of generalist species.

**Parasitism

A relationship in which one organism lives on or in a host and harms it.

Highly specialized species tend to evolve on islands because of the environmental conditions and resource availability. Based on the theory of island biogeography, which of the following would most likely experience the greatest decline of specialist species if an invasive species emigrated from the mainland?

A small island in close proximity to the mainland. Being close to the mainland increases immigration of species. A small island has fewer niches available and specialized food webs, which is most likely to cause substantial declines in specialist species.

**Keystone Species

A species that influences the survival of many other species in an ecosystem

Which of the following aspects of the design for this new urban development will best help to reduce the amount of carbon dioxide released into the atmosphere?

Access to the mass transit train line will provide inhabitants an alternative to driving personal vehicles.

By the year 2050, world population is expected to approach 10 billion. If the current population trends continue, which region of the world will most likely experience the majority of the growth?

Africa and Asia

The demographic transition model describes population change over time as a country becomes more developed. Age-structure diagrams describe how populations are distributed across age ranges. Which of the following age-structure diagrams best displays the age ranges in a country that is in stage 2 of the demographic transition?

An expansive pyramid age-structure diagram

Which of the following statements best describes an unintended environmental consequence of aquaculture fish-farm enclosures located in estuaries?

Aquaculture enclosures can harbor parasites that can negatively affect wild populations that breed in estuaries

Which of the following would be considered an advantage of increased urban sprawl?

As individuals move out of urban areas to nearby suburbs, the population densities of cities will decrease, reducing the spread of infectious disease.

Based on current trends and patterns, which of the following statements best predicts how the human population will change over the next 50 years?

As the population density increases, there will be an increase in disease transmission, leading to increased mortality.

Plant roots absorb ammonium ions and nitrate ions for use in making molecules such as DNA, amino acids, and proteins.

Assimilation

Which of the following claims best supports the classification of bees as an organism that displays a Type II survivorship curve, as shown in the graph above?

Away from the colony, bees experience a constant probability of death per unit time as a foraging species

Which of the following describes why the summer solstice in Australia occurs in December and not in June?

B At this time of year, the tilt of Earth causes Australia to receive highly concentrated solar radiation.

Which of the following types of organisms are required to complete the nitrogen cycle, including the process of denitrification?

Bacteria. Certain bacteria are specialized in fixing nitrogen, in association with plants such as soybeans and other legumes. Other types of bacteria perform nitrification: converting ammonium ions into nitrite ions, and then into nitrate ions. Finally, other bacteria perform denitrification, the reduction of nitrates back into nitrogen gas.

The country with the highest population density is...

Bangladesh

Determining Soil Texture

Both the soil triangle and density gradient tube are used to determine the texture of a soil sample. A soil density gradient tube, which separates particles by density, would help determine a soil profile. Using a soil triangle, the soil texture can be determined using the percentage of sand, silt, and clay from the soil profile.

Based on the food web shown above, which of the following correctly describes the flow of energy through the trophic levels from producers to quaternary consumers?

Brittlebrush, grasshopper, grasshopper mouse, rattlesnake, red-tailed hawk. The energy flows up the food web through trophic levels based on feeding relationships.

This rate of reaction can be measured in the dark by determining the amount of oxygen gas consumed in a period of time.

Cellular Respiration. Sunlight (solar energy) is required for primary productivity.

Which of the following foods is most suitable to cultivate to minimize water consumption per kilogram of food?

Cereals

This biome is found in shallow waters off the coastline and is Earth's most biologically diverse marine biome

Coral reefs. Corals live in vast colonies off the coast and create a reef that provides habitat for a variety of organisms, including algae, tropical fish, and birds.

Based on the diagram above, which process most directly results in the storage of carbon as coal and oil over millions of years?

Decomposition of producers and consumers has led to the storage of carbon over millions of years. In the cycle presented, decomposition is the most direct cause of this storage.

Of the following organisms, which occupies the lowest trophic level?

Deer

Which of the following pathways indicate how nitrogen is added to the largest nitrogen reservoir?

Denitrifying bacteria and volcanic activity. The atmosphere is the major reservoir of nitrogen. About 78 percent of our atmosphere is composed of nitrogen gas

This biome contains plants that are adapted to prevent water loss due to the low average rainfall and high temperatures year-round

Deserts are hot and dry year-round, and plant species are adapted in a variety of ways (small leaves, stems that store water, and modified spines) to reduce water loss.

Which of the following best describes the movement of energy in an ecosystem?

Energy is harnessed by producers, and available energy decreases with each trophic level transfer.

**First Law of Thermodynamics

Energy is neither created nor destroyed, but may be converted from one form to another.

Overfishing of stocks of fish species, like salmon and cod, in an effort to meet a growing global demand has become an international concern. A recent estimate indicates that the average annual consumption of fish globally in 2014 was about twice the consumption in 1960. Because of increased concerns about the impact of overfishing, fishery managers are looking for ways to protect wild populations while still satisfying global demand for food for human consumption. Various nations have adopted policies designed to combat overfishing. Which of the following approaches is commonly used to combat the problem of overfishing?

Enforcing minimum-size requirements for the capture of some commercial species

Which of the following changes to the local hydrologic cycle will result if large areas of land experienced clear-cutting?

Evaporation of water from the soil will increase. Lack of trees and other plants increases the amount of direct sunlight and heat absorption, causing increased evaporation from the soil.

Which of the following is a negative consequence of aquaculture?

Excessive amounts of nitrogen and phosphorus can leak from the location.

El Niño and La Niña are natural phenomena associated with changing water temperatures in the Pacific Ocean. The occurrence of these events can result in changes in global weather and ocean circulation patterns. Which of the following is a positive effect likely to result from an El Niño event?

Fewer hurricanes forming in the Central Atlantic basin

Aquaculture or fish farming can be used to increase the availability of species like salmon and shrimp for consumption. Although fish farming can have a number of negative environmental effects, it does offer a number of advantages. Which of the following is a valid reason for promoting the use of fish farms?

Fish production is constant, and fish farming reduces pressure on wild stocks

Which of the following is a process that indirectly removes carbon from Earth's atmosphere?

Formation of carbonate deposits

This biome contains a nutrient-rich environment created by falling leaves and trapped organic materials from the large trees, and it provides the ecosystem service of filtering pollutants from water.

Freshwater wetlands have trees with roots that are submerged in water. The trees drop their leaves, and the water traps organic materials released from decomposition. The wetlands also trap pollutants.

A scientist is studying a biome that experiences large seasonal fluctuations in both temperature and precipitation patterns. Which of the following would best characterize the organisms that inhabit the biome?

Generalists would be most abundant, because the resources available would be constantly changing.

Student 5 decides to take action to lower his or her overall footprint by reducing money spent on shoes and clothing. Land use in which of the following categories will be most affected by this change?

Goods and services. Material goods fall into the category of goods and services. Reducing consumption and spending on new clothes and shoes would lower the land use and resources needed to produce new items

The total rate of photosynthesis in a given area.

Gross primary productivity

Which of the following density-independent factors can affect the size of a human population?

Heat waves will affect people if there are few or many in an area; the effects are independent of population density.

Which of the following smaller reservoirs of freshwater are missing from the diagram?

Ice caps (and glaciers) store almost 70% of the Earth's total freshwater.

Energy is transferred along food chains from one stage to the next. Which statement best explains how the energy is transferred?

If a primary producer stores 10,000kcal of energy, then a tertiary consumer will have 10kcal of energy available.

Which of the following best describes the first law of thermodynamics?

In a closed system of constant mass, the energy involved in any physical or chemical change is neither created nor destroyed, but merely changed from one form to another.

The diagrams above show an area that was once a pasture that has since undergone changes to the vegetation over time. Which of the following changes in the hydrologic cycle is most likely to occur as a result of the change in vegetation in the area?

Increased infiltration

During a La Niña event, what environmental changes would the tropical Pacific Ocean and its surrounding landmasses most likely experience?

Increased upwelling off the coast of South America resulting in increased productivity of fisheries

After intensive logging, most of the trees along a stream have been removed. Which of the following water quality changes would most likely occur downstream after logging?

Increased water temperature. Increased erosion would occur when the soil is no longer held in place by the tree roots. This will increase the turbidity of the stream and cause the temperature to increase. Additionally, the lack of trees around the stream would most likely increase the amount of solar insolation on the stream, leading to higher temperatures

The country with a population about three times that of the United States is...

India

Which of the following statements best describes why birth and death rates are changing in a country that is in Phase 2 of the demographic transition?

Individuals have better sanitation and access to clean drinking water.

Based on the map, which of the following best explains the area of the Andes Mountains that would have the greatest number of rivers?

More rivers would be located on the east side of the Andes Mountains because the trade winds are coming from the east.

In reef ecosystems, corals often have microalgae living inside them. The algae supply the corals with nutrients, and the coral give shelter to the algae. Which of the following interactions best describes the relationship between the corals and the algae?

Mutualism. The two organisms both benefit from the relationship.

Which of the following best describes the net primary productivity of an ecosystem?

Net primary productivity is the amount of energy lost through respiration by producers subtracted from the gross primary productivity of an ecosystem.

The energy available to consumers determined by subtracting the energy used by plants from the total energy transformed by the process of photosynthesis.

Net primary productivity is the rate of energy storage by photosynthesizers after subtracting energy used for cellular respiration in plants.

Which of the following processes is illustrated by the downward arrows from the atmosphere that show the conversion of nitrogen gas into usable forms available to producers?

Nitrogen fixation. Nitrifying bacteria or lighting converts atmospheric nitrogen N2 to ammonia.

**Abiotic

Non-living things

Which of the following best exemplifies how an action within the fishing industry could lead to a tragedy of the commons?

Overfishing of threatened fish species leading to the eventual depletion of the resource

Which of the following describes the dependent variable in this investigation?

Percentage of each particle size in each soil sample

Which of the following elements is most likely to limit primary production in freshwater lakes?

Phosphorus

Which of the following trophic levels represents a primary producer in an aquatic food chain?

Phytoplankton uses solar energy to produce food; it is a producer.

The Mississippi watershed is the largest in North America, draining all or part of thirty-two states in the United States and two Canadian provinces. A new apartment complex is being built on a steep slope near the source of the Mississippi River outside of Minneapolis, Minnesota. Which of the following measures should be taken to best reduce erosion at the construction site to protect the Mississippi watershed?

Plant grass and shrubs on the slope.

Which of the following describes the changes in a country's demographics as it begins its transition from a preindustrial state to an industrial state?

Population increases rapidly, birth rate remains high, death rate decreases

**Nitrogen Fixation

Process of converting nitrogen gas into ammonia

Which of the following best describes the flow of energy in most terrestrial and near-surface marine ecosystems?

Producers use energy from the sun to make organic matter, such as sugars, from carbon dioxide and water and are then consumed by organisms higher in the food chain. Through the process of photosynthesis, plants convert solar energy into chemical energy, which moves through the food chain when one organism feeds on another.

Which of the following best describes a disadvantage of creating a series of protected habitats in an effort to maintain biodiversity in an area?

Protected habitats often separate species inside the habitat from other populations of the same species living outside the habitat.

Aquaculture enclosures can harbor parasites that can negatively affect wild populations that breed in estuaries

Raising fish using aquaculture and feeding human populations with the harvest reduces the number of fish caught from the ocean.

Which of the following would decrease with the manufacture, application, and use of synthetic fertilizers rather than organic fertilizers?

Recycling of organic matter

A developer wants to develop a large tract of land near a watershed, which will require the removal of several large trees. Which of the following statements best describes the impact that the development would have on the watershed?

Removing large trees would cause an increase in temperature and keep the surrounding water and soil warmer.

This freshwater biome is characterized by fast-flowing water that can originate from underground springs or runoff, which carries sediment and organic material.

Rivers carry runoff from rain or snow. Turbulent water, known as rapids, form from the fast-moving water flow.

Based on the diagram, which of the following reservoirs contains the most phosphorus?

Sediments

A group of students wanted to determine if soil texture can vary by location. Several students brought in a sample of soil from their backyards. Each student added their soil sample of equal mass to a jar with exactly the same amount of water, shook the contents so that all soil particles were suspended in the water, and left the jars covered overnight. The next morning, the soil particles had settled out into layers and students could determine the percentage of each type of particle. Which of the following describes the independent variable in this investigation?

Soil samples taken from different locations

The vast majority of ozone (O3) is found in a thin layer due to a lack of circulation in which of the following atmospheric layers?

Stratosphere

Which of the following abiotic factors, when graphed on the x-axis, leads to the curved line in the graph due to variation in the different layers of the atmosphere?

Temperature gradients

Which of the following best identifies a key component of the hydrologic cycle that powers the movement of water and is missing from the diagram?

The Sun powers the movement of water through evaporation and transpiration.

Which of the following best describes the concept of the tragedy of the commons?

The aim of large logging operations in tropical rain forests is economic gain, rather than sustainability. Therefore, the shared resources in the forest could become depleted.

Which of the following is an assumption made by the author regarding the use of genetically modified crops?

The amount of arable land will remain relatively constant, and the growing human population will have enough food if more crops can be harvested from the same amount of land.

A country is currently in the second stage of the demographic transition. Currently the country has a birth rate of 37.9 births per 1,000 individuals and a death rate of 13.4 deaths per 1,000 individuals. Which of the following changes would indicate that the country is moving from the second stage into the third stage of the demographic transition?

The birth rate declines to 25.3 births per 1,000 individuals.

Which of the following biogeochemical cycles includes the processes of buffering ocean pHand photosynthesis, as shown in the diagram?

The carbon cycle.

Based on the map, which of the following best identifies and explains the region of South America that would have a more moderate climate?

The east coast would have a more moderate climate because of the Brazil Current.

Which of the following explains what is being illustrated in the enclosed area in the northwest portion of the map?

The enclosed area shows a hot spot in the middle of the Pacific Plate in the Hawaiian Islands.

An urban planner is designing a new urban housing development in a currently rural area near an existing city. The urban development will have five 10-story apartment buildings, two basketball courts, a playground with permeable foam pavers, a 10-acre green space with a small man-made pond, one 5-story parking deck, and direct access to the mass transit train line. Which of the following aspects in the design for this new urban development would most likely have the greatest negative environmental impact?

The five apartment buildings

Which of the following describes the most likely change to terrestrial biomes resulting from warmer average global temperatures?

The global distribution of midlatitude biomes, such as grasslands and temperate rain forests, would increase.

Half a century ago disaster loomed just as ominously (as today). Speaking about global hunger in 1959, one economist said, "At best the world outlook for the decades ahead is grave; at worst it is frightening." Before those visions could come to pass, the green revolution transformed global agriculture, especially wheat and rice. [S]elective breeding created a dwarf variety of wheat that put most of its energy into edible kernels rather than long, inedible stems. The result: more grain per acre. Similar work in the Philippines dramatically improved the productivity of the grain that feeds nearly half the world. From the 1960s through the 1990s, yields of rice and wheat in Asia doubled. To keep doing that between now and 2050, we'll need another green revolution. There are two competing visions of how it will happen. One is high-tech, with a heavy emphasis on continuing breeding better crops, but with modern genetic techniques. "The next green revolution will supercharge the tools of the old one." Scientists, he argues, can now identify and manipulate a huge variety of plant genes, for traits like disease resistance and drought tolerance. That's going to make farming more productive and resilient. The signature technology of this approach—and the one that has brought both success and controversy to Monsanto—is genetically modified, or GM, crops. First released in the 1990s, they've been adopted by 28 countries and planted on 11 percent of the world's arable land, including half the cropland in the U.S. About 90 percent of the corn, cotton, and soybeans grown in the U.S. are genetically modified. Americans have been eating GM products for nearly two decades. But in Europe and much of Africa, debates over the safety and environmental effects of GM crops have largely blocked their use. A recent study by the U.S. Department of Agriculture found that pesticide use on corn crops has dropped 90 percent since the introduction of Bt corn, which contains genes from the bacterium Bacillus thuringiensis that help it ward off corn borers and other pests. Reports from China indicate that harmful aphids have decreased—and ladybugs and other beneficial insects have increased—in provinces where GM cotton has been planted. The green revolution has improved global agricultural output. Which of the following best describes the author's perspective on the beginning of the green revolution in the 1970s and 1980s?

The green revolution was successful because of selective breeding, which improved nutritional value and crop yield to increase food production.

Which of the following biomes is best characterized as an area that forms the narrow band along the coast that experiences a range of environmental conditions (including daily changes in sunlight, temperature, and water) ?

The intertidal zone is found along coastlines (from rocky cliffs to sandy beaches) that experience different levels of high and low tide. Organisms that inhabit these areas must be adapted to withstand changes in direct sunlight, temperature, and desiccation as well as the crashing waves.

The majority of the nitrogen on Earth can be found in which of the following reservoirs?

The largest reservoir of nitrogen is the atmosphere, which is about 80% free nitrogen (N2) and contains 3,870,000,000 tetragrams of nitrogen.

**Troposphere

The lowest layer of Earth's atmosphere

Which of the following major storage reservoirs of carbon, stored in the form of carbon dioxide, is not represented in this diagram?

The ocean.

Researchers monitored the number of reindeer over time on an island off the coast of Alaska. The reindeer were introduced in year 1, and the population size was counted every 5 years. The data are shown in the table above. Which of the following claims about trends in the population size over time is best supported by the data?

The population exceeded the carrying capacity of the island, which led to a decrease in the population size following extreme resource depletion.

A 163 square-kilometer (km2) small island is found 2,000km from the mainland. A second, larger, 230,000km2 island is found 1,000km from the mainland. Based on the theory of island biogeography, which of the following statements is most likely true about the small island when compared with the large island?

The rate of species extinction is lower on the small island than on the large island.

Which of the following describes an unintended consequence that results from large-scale agricultural use of water from an aquifer?

The rate of water use likely exceeds the rate of recharge, leading to lowering the water table.

This biome is characterized by long dry seasons and is dominated by grasses, shrubs, and grazing animals.

The savanna has long dry seasons, with grazing animals and fire that prevent the growth of many woody plants.

**Stratosphere

The second-lowest layer of Earth's atmosphere.

Six white-tailed deer and six sika deer were enclosed in a pasture for observation during an eight-year study in central Texas. White-tailed deer are a native species to central Texas, while sika deer are a nonnative species to central Texas. White-tailed deer feed on flowering plants and the tips of trees and shrubs but do not eat grass. Sika deer feed on flowering plants, the tips of trees and shrubs, and grass. All other grazing animals were kept out of the pasture during the study. The number of sika deer more than doubled after the eight years, while the population of white-tailed deer decreased by 50 percent. Which of the following statements best supports the results from the study?

The sika deer out competed the white-tailed deer in consuming flowering plants and shrubs.

A student claims that soil sample B would be classified as a loam. Which of the following best describes the method used by the student to reach this conclusion?

The student used a soil triangle to determine where the lines intersect for sand, silt, and clay for the soil sample.

Based on the diagram, which of the following days in Earth's yearly orbit would have the longest period of daylight in the Northern Hemisphere?

The summer solstice is on June 21 in the Northern Hemisphere, when the Earth's North Pole has its maximum tilt toward the Sun. The summer solstice is when the Sun is at its highest position in the sky and the day has the longest period of daylight. Day length on this day ranges from about 13 hours (in Hawaii) to almost 24 hours (in northern Alaska).

Which of the following is the best explanation for the deflection of the trade winds in both hemispheres?

The wind is deflected west because of Earth's rotation

A student is setting up a model to study the carbon cycle and natural sources of carbon dioxide. They create a microenvironment that contains soil, leaf debris, an earthworm, heterotrophic bacteria, and a sun lamp. What natural source of carbon dioxide and major metabolic process was left out of the model?

There is no representation of photosynthesis in the model environment.

Which of the following environmental effects would most likely result from the clear-cutting of boreal forests by industrial logging operations?

There will be an increase in atmospheric carbon dioxide concentration, which will contribute to climate change.

Which of the following layers of the atmosphere contains charged gas molecules that glow and produce light when hit by solar energy, leading to glowing gases such as the northern lights, found over 90 kilometers above Earth's surface?

Thermosphere

Which of the following best describes the advantages and disadvantages of drip irrigation?

This method most efficiently delivers water directly to plant roots compared with other methods, and wastes less water, but it may be too costly for farmers in developing countries to use.

Which of the following best describes the trends seen in the total fertility rates for the world population from 1950 to the projected rates in 2040 ?

Total fertility rates declined rapidly from 1960 to 2000 because women had children later in life as a result of increased educational opportunities.

Which of the following terrestrial biomes has the highest net primary productivity?

Tropical rain forest. Net primary productivity (NPP) is higher in biomes that are warm year-round and receive abundant rainfall and sunlight to encourage the growth of producers, which are all characteristics of tropical rain forests.

Which of the following terrestrial biomes has the highest primary productivity per unit area?

Tropical rain forests have a yearlong growing season and more than 60 inches of rain per year. The warm climate and the rainfall leads to high levels of photosynthesis in the numerous plant species that inhabit the biome.

Which of the following best describes an example of resource partitioning in an ecosystem?

Two different bird species feed from the same oak tree; one eats acorns, and the other eats insects in the bark. The two bird species are using the same resource in slightly different ways to reduce the negative impact of competition on the two species.

Which foods are the most sustainable to produce in order to provide the most kilocalories to the world's growing population while still minimizing water usage?

Vegetables

Which of the following best describes a terrestrial ecosystem that will have the highest net primary productivity?

Warm temperatures, high rainfall, and consistent sunlight

Based on the diagram, which of the following statements about the hydrologic cycle is true?

Water from the ocean evaporates and condenses in the atmosphere.

An environmental agency wants to evaluate the effectiveness of rain gardens in reducing the impact of urban runoff from an impervious parking lot and from the roof of the building. The parking lot is slightly sloped so the rainwater flows toward the gardens. The runoff from the roof is collected by various downspouts and directed toward the gardens. Scientists at the agency plan to monitor the effectiveness by measuring the water quality of the storm water as it moves through the gardens during and after storm events. Which of the following would be the best control in this experimental design?

Water samples collected from the roof or parking lot before they passed through the gardens

During an El Niño event, farmers in the southwestern United Stated often benefit from which of the following climatic changes?

Wetter and warmer weather that increases soil moisture

**Second Law of Thermodynamics

When energy is changed from one form to another, some useful energy is always degraded into lower quality energy (usually heat).

**Nitrification

ammonia is converted to nitrate ions (NO3-).

**Commensalism

an association between two organisms in which one benefits and the other derives neither benefit nor harm.

**Denitrification

bacteria convert ammonia back into N.

**Preindustrial stage

birth and death rates high, population grows slowly, infant mortality high

**Industrial stage

decline in birth rate, population growth slows

**Ammonification

decomposers convert organic waste into ammonia

**Assimilation

inorganic N is converted into organic molecules such as DNA/amino acids & proteins.

**Biotic

living things

**Postindustrial stage

low birth and death rates

**El Niño (ENSO)

prevailing winds in the Pacific weaken and change direction every few years which results in above average warming of eastern Pacific waters, which changes distribution of plant nutrients and alters earth's weather for 2-3 years

**Trophic Levels

producers → primary consumer → secondary consumer → tertiary consumer.

**Leaching

removal of dissolved materials from soil by water moving downwards through soil.

**r-strategist

reproductive strategy in which organisms reproduce early, bear many small, unprotected offspring (ex. insects, mice).

**k-strategist

reproductive strategy in which organisms reproduce late, bear few, cared for offspring (ex. humans, elephants).

**Tragedy of the Commons

situation in which people acting individually and in their own interest use up commonly available but limited resources, creating disaster for the entire community

**Mutualism

symbiotic relationship in which both species benefit from the relationship

**Divergent plate boundaries

tectonic plates spreading apart, new crust being formed (ex. mid-ocean ridges, rift valleys).

**Convergent plate boundaries

tectonic plates with the oldest crustal material on Earth moving together, one moving under another (ex. mid-ocean trenches). Mineral deposits and volcanoes are most abundant at convergent plate boundaries