AP Environmental Science : Ecological Change
Study concepts, example questions & explanations for AP Environmental Science
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Example Questions
Example Question #5 : Natural Selection
An organism's fitness, as it applies in natural selection, involves __________.
the number of their offspring that reproduce themselves
the efficiency with which they hunt
their ability to chase prey for extended periods of time
the number of mates with whom they reproduce
the number of their offspring that reproduce themselves
In natural selection, the term fitness means how successful the organism is in reproducing. If an organism has a large amount of offspring, but lives half as long as its similar organisms, it is still more successful because its genes will be apart of more offspring, who will reproduce themselves.
Example Question #6 : Natural Selection
In a particular habitat, Species A competes with Species B for food resources. Which type of competition is this?
Intraspecific interference competition
Interspecific interference competition
Intraspecific exploitation competition
Interspecific exploitation competition
Interspecific exploitation competition
Interspecific competition is that which occurs between two different species. Exploitation competition involves the two groups of organisms competing for a limited resource, which may or may not involve direct contact between the species. Interference competition involves direct contact between organisms.
Example Question #21 : Ecological Change
What is the term for the formation of new species through the course of evolution?
Allele frequency
Bottleneck effect
Speciation
Fecundity selection
Speciation
Speciation is the term for formation of new species throughout the process of evolution. Isolated groups might split off from a species to become an entirely different species. This could be caused from changes in selection pressures, mutations, or genetic drift.
Example Question #21 : Ecological Change
Which of the following is an example of primary succession?
An ecosystem diversifying, supporting more species and increases in biomass
A plant community becoming simplified with fewer species and less biomass
Plant communities are established in a lifeless environment, usually devoid of soil
A succession of larger plants (trees, shrubs, etc.) following the establishment of pioneer species
A transition from one ecosystem type to another
Plant communities are established in a lifeless environment, usually devoid of soil
Primary succession commonly occurs after a volcanic eruption or a glacier recedes, because these areas have been stripped of organic matter. Primary succession is the process by which pioneer species colonize an area otherwise uninhabitable for plant life and generate nitrogen for other plant communities.
Example Question #22 : Ecological Change
Which of the following provides the most accurate example of primary succession?
Lichens re-establish themselves on rocks and shallow soil beds following a tundra fire
Seedlings establishing themselves in a heavily logged area where the seed-tree cutting method was employed
Native grass communities forming after a wildfire burned through a meadow/woodland ecosystem
Coral reef and aquatic wildlife communities that have re-established themselves in regions of the South Pacific that were evacuated following the nuclear tests conducted by the U.S. military
Lichen and grass communities establishing themselves on a recently-formed island, resulting from an uplift in the ocean bedrock
Lichen and grass communities establishing themselves on a recently-formed island, resulting from an uplift in the ocean bedrock
Primary succession is characterized by plants establishing themselves in areas that were initially devoid of soil (usually bedrock). Grasses establishing themselves on a newly-formed island that is mostly bedrock is the best fit for this definition.
Example Question #23 : Ecological Change
Which of the following is the most accurate example of secondary succession?
Lichens and small spruce trees have established themselves in regions of Alaska where glaciers once existed but have since receded.
A forest fire burns down crowded understory grasses and shrubs as well as some ponderosa pine stands in the Black Hills of South Dakota.
Following the Dust Bowl of the 1930's, prairie grasses reestablished themselves in areas had lost most of their fertile soil to wind erosion.
In 1962, a volcanic eruption off the coast of Iceland resulted in a formation of a new island "Surtsey" from ocean bedrock.
Twenty years after the Mount St. Helens eruption, small trees and grasses have begun to regrow near the top of the peak, where the eruption occurred.
A forest fire burns down crowded understory grasses and shrubs as well as some ponderosa pine stands in the Black Hills of South Dakota.
Primary succession is characterized by a total loss of biomass and soil from the ecosystem or a beginning lack thereof. Land that has been covered by a glacier or under the seabed will be devoid of soil, much like the exposed bedrock seen after the Dust Bowl or the Mount St. Helens eruption. By contrast, a forest fire can typically be characterized as secondary succession because the soil remains intact and the ecosystem can typically recover much quicker because of that fact.
Example Question #24 : Ecological Change
Which of the following would NOT contribute significantly to primary succession?
Pre-existing nitrogen-fixing plant communities
Wind-carried soil particles and nutrients
Feces from wildlife populations that occupy the region
Soil nutrients deposited by a nearby river
The time-consuming process of weathering the bedrock into smaller particles
Pre-existing nitrogen-fixing plant communities
Primary succession is characterized by pioneer species establishing themselves in areas that are predominantly bedrock and devoid of organic material. The formation of organic material in these areas typically occurs with the accumulation of wind-carried soil erosion, nutrients deposited by flowing bodies of water, and erosion of bedrock. Wildlife populations are also a significant contributor of soil nutrients, with feces being rich in both nitrogen and phosphorus. In contrast, pre-existing nitrogen-fixing plants (or any pre-existing plant communities) are uncommon to nonexistent in an area with no established soil system.
Example Question #2 : Ecological Succession
Which of the following is a structural change in a community and its nonliving environment over time that alters the ecosystem?
Evolution
Natural selection
Succession
Mutation
Adaptation
Succession
Succession is a structural change in a community and its nonliving environment over time. Community changes alter the ecosystem in ways that favor competitors, and species replace one another in a somewhat predictable manner until a stable community is reached. Examples are the changes that occur after volcanos erupt and forest fires. Adaptation is a characteristic of an organism that helps it survive and reproduce in a particular environment. The differential survival and reproduction on the basis of genetic differences among individuals is termed natural selection. Evolution is any change in the proportions of different genotpyes in a population from one generation to the next. Mutation is a change in the base sequence of DNA in a gene that is usually significant enough to alter the appearance or function of the organism.
Example Question #4 : Ecological Succession
Which of the following are least likely to be present during primary succession?
Trees
Grass
Moss
Lichen
Trees
Primary succession begins with no soil. Eventually, lichens and mosses grow and die, which creates some soil. Small plants such as grasses and some ferns use this soil and grow. It would be very unlikely for a tree to grow in this environment.
Example Question #3 : Ecological Succession
Ecosystems recover from disturbances in unique ways. A landscape ecologist observes in area right after a volcanic eruption. There is lava and dust across the landscape, and all vegetation has been removed. What is this ecosystem experiencing?
Primary succession
None of these
Pioneering succesion
Secondary succession
Climax succession
Primary succession
The correct response is primary succession. This represents the initial growth following a disturbance, such as a volcanic eruption. While pioneering succession involves the colonization of a location that has been affected by ecological damage, primary succession is a better answer since it refers specifically to vegetation colonizing a location in which soil is absent (such as after a volcanic eruption). Climax succession is not a term used to describe species succession over time, rather, a climax community is one that, over time, has reached a steady state.
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