Biodiversity - AP Environmental Science

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Question

Which of the following is the best example of critical habitat?

Answer

Critical habitat is defined as vital for sustaining endangered or threatened populations. The whooping crane is endangered and requires wetland ecosystems to sustain a population, while the other examples are situations where alternative (albeit less successful) habitat was available or the population was neither threatened nor endangered.

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Question

What is the approximate proportion of amphibian species worldwide that are at risk of extinction?

Answer

Amphibians are one of the most susceptible groups of species to mass extinction, with one in three currently at risk of extinction.

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Question

How does the 6th mass extinction significantly differ from the other 5 mass extinctions that have occurred throughout the history of Earth?

Answer

Previous extinction events can be attributed to pathology, climate change and other natural factors. The current 6th mass extinction event is largely attributed to human activities and the resulting climate change.

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Question

Diversity can be calculated at various scales. Which type of diversity refers to the total number of species in a geographic region that spans multiple habitats?

Answer

Gamma diversity refers to the total number of species within a region. This can also be referred to as regional diversity. Gamma diversity is useful in order to investigate biodiversity from a broad scale or at the landscape level.

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Question

In the 1960s, Robert MacArthur and E.O. Wilson came up with one of the most prominent theories in the field of ecology—Island Biogeography Theory. This theory describes the balancing of which of the following two processes?

Answer

Island Biogeography Theory is related to the balancing of immigration and extinction. In short, the number of species that occurs on an island should be directly related to the rate of extinction and the rate of immigration. If the rate of immigration is higher than the rate of extinction, then the number of species will be high. If the rate of extinction is higher than the rate of immigration, then the number of species will be low.

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Question

The ecologist Joseph Connell studied tropical rain forests and noticed that they contain high levels of biodiversity compared to temperate zones. He noted that earthquakes and storms are important forces that continually open canopies and create new habitat for species colonization. Which of the following hypotheses best describes this phenomenon?

Answer

The Intermediate Disturbance Hypothesis describes how habitats experiencing moderate levels of disturbance can support the most species. This occurs because disturbance initiates the turnover of dominant species, which allows new species to emerge. For example, a tree falling in the forest could be an example of a disturbance. Trees falls open up the canopy and allow sunlight to reach the floor of the forest and creates an open space for species to colonize.

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Question

Beta diversity refers to the difference in species across habitats. If an area of particular interest has 8 different habitats and an average of 3.2 species occupying each habitat, then what would the beta diversity be?

Answer

Beta diversity is calculated by taking the total number of habitats divided by the number of species in each habitat of a given environment.

Total number of habitats:

Number of species in each habitat:

Solve:

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Question

Biological diversity is the variation between organisms in a ecosystem; both plant and animal.

What three aspects are taken into account when measuring biological diversity?

Answer

Biological diversity is concerned with not only the number, variety and variability of species within ecosystems but the number of ecosystems on the Earth and genetic diversity within species.

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Question

Riparian zones are important because __________.

Answer

Riparian zones prevent erosion and are incredibly high in biodiversity. Riparian areas are thin and ribbon-like, accompanying streams and rivers, but often long and dense.

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Question

Which is not a value of every species on Earth?

Answer

Every species is important because of its niche in its ecosystem. Additionally, all species are potentially of scientific and medical/economic value.

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Question

Imagine that there is a museum that contains every species that has ever lived on planet Earth. Of all the species that have ever existed on Earth, what percentage of those are still alive today?

Answer

The correct response is 1%. The majority of species that have ever lived on Earth are extinct. Mass extinctions have occurred throughout geological history due to large disturbances such as meteor crashes and ice ages. Life is fragile and disturbances can cause millions of species to go extinct rather quickly - such as most recent mass extinction when the dinosaurs disappeared. Thus, the species still alive today represent a tiny portion of the variety of life that has existed throughout the geological history of Earth.

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