Ecosystems and Biology - AP Environmental Science

A species is "endemic" when it is found only in one particular location. The flightless cormorant, marine iguana, and Galapagos penguin are all examples of species that are endemic to the Galapagos Islands.

The correct answer choice is biodiversity. Biodiversity is the area within biology focused on understanding biological diversity. The terms "disturbance" and "fragmentation" are natural processes that can have impacts on species, but they do not describe species. The terms "biomagnification" and "bioaccumulation" describe how nutrients and contaminants accumulate over time.

The correct response is indicator species. If the indicator species is healthy, then it tells or indicates that the ecosystem as a whole is healthy. Indigenous species are native to a certain location, while invasive species are those that are not native to a location and their introduction usually causes harm to the existing ecosystem. A keystone species is one that plays a critical role in the overall health of an ecosystem.

Olfaction in fish and other marine life is very important. Smells are carried on currents and can be used to identify and find prey, recognize familiar territory, attract mates, and warn predators and/or competitors of defense mechanisms.

Somewhere between 40% and 75% of all species are indigenous to rainforests, meaning that they are found nowhere else on earth. They contain half of the extant animal and plant species currently on earth, with a large majority of all flowering plants found there. Many of the world's natural medicines have been found in tropical rainforests, and with thousands of undiscovered species still lurking within them, it is likely that there are many more medicines waiting to be discovered.

In relationships based upon commensalism, one of the species benefits greatly, while the other is neither harmed nor helped. This is different from mutualism, where both species are benefited, and parasitism, where one species is benefited and the other is hindered. "Endosymbiosis" is the theory used to describe how mitochondria developed, and "predation" describes a situation where one organism feeds on another.

All of these are caused by water in some way, however, gully erosion is due to steady and fast-flowing streams; the Grand Canyon is an excellent example of the effect of gully erosion. Splash erosion is the first step in erosion from water, and involves the breakage of soil via the impact between soil and a raindrop. It is often a precursor for other types of erosion since it loosens soil. Sheet erosion involves evenly removing a certain number of layers of material due to regular water patterns. Rill erosion is a result of small, well-defined paths of water known as rills, that flow downhill after rainfall.

Today, 99.9% of all species that have ever existed on Earth are extinct. We are currently in the middle of the 6th mass extinction. The dinosaurs went extinct during the 5th, the Cretaceous, about 65 million years ago.

The correct response is Milankovitch cycles. This theory describes how the orbit, tilt, and axis of the Earth operate on a 100,000 year cycle that cause the Earth to be further from the sun. As the Earth gets farther from the sun, it can trigger an ice age. The theory is aptly named after the man who discovered it. The El Nino and La Nina events occur on a much shorter time scale and have nothing to do with ice ages.

The Wallace Line, named for Alfred Russel Wallace, is a boundary that separates Asia and Australia. Wallace noticed that the some of the islands in this region contained species common to Australia and some contained species common to Asia, none of which would have crossed the open water in between the continents. Wallace correctly reasoned that this meant that sea levels were once much lower, an artifact of the last glacial maximum.

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.

Least concerned refers to the lowest risk where species members are abundant. Near threatened means the species is likely to become endangered at some point. Vulnerable means that, in the wild, the species are at high risk for becoming endangered. Endangered is similar to vulnerable, but has a high risk of extinction, not just endangerment. Extinct means there are no more members of the individuals in a species remaining. The correct ranking is as follows: least concerned, near threatened, vulnerable, endangered, and extinct.

Population growth is an underlying cause of depletion and premature extinction of a wild species, but is not a direct cause. On the other hand, habitat loss is a direct cause of depletion and premature extinction of wild species due to processes like over logging, damming rivers, or urban development. Pollution is a direct cause of extinction in the wild, usually caused as streams, rivers, and oceans are polluted. The introduction of an invasive, nonnative species to an environment can create an unbalanced ecosystem, directly causing extinction of wild species. These invasive species are often harmful and fill niches previously occupied by native species. Increasing predator species in an area can significantly reduce or drive prey species to extinction. Similarly, increasing the use of pesticides and pest controls can directly cause extinction of organisms in the affected ecosystem.

A population is a collecting of individuals from the same species. Populations are a unit of organization that has measurable properties, such as population density and home range. Populations are altered by birth and death, immigration, and emigration.

The correct answer is “metapopulation model.” It describes multiple sub-populations that are connected together in a larger, metapopulation. This is typically shown as patches within a larger landscape. The patches represent sub-populations. Individuals can migrate from one patch to another, but they are all part of the same population.

The correct answer is “evenness.” All the other terms describe life history traits. “Maturity” refers to the age of first reproduction. “Parity” is described as the count of reproduction events. Last, “fecundity” is defined the number of offspring at each reproduction event.

The correct response is “keystone species.” A keystone species makes up a small portion of community; however, it has a major impact on the community structure despite making up a small percentage of the ecosystem that it inhabits. "Dominant species" have large number and large impacts; thus, this answer choice does not fulfill the disproportionate part of the description. "Common species" and "rare species" both have low impacts on the community structure, so they are poor answer choices.

The correct response is "ecosystem engineer." An ecosystem engineer manipulates and engineers the habitat to benefit them in a significant way. If an ecosystem engineer like the beaver is removed from the environment, it can have detrimental effects on other species and the community structure.

The I=PAT equation was developed in the 1970s and it describes the impact of human population, affluence and technology on the environment. The equation is used as an aid in understanding how the size of a population, its affluence (i.e., the average consumption of each person), and the efficiency level of the population’s technology will affect the population’s general impact on the environment. The equation is simplistic and should not be seen as an accurate assessment of a population. Rather, it is a thought-provoking tool.