Ecosystems and Biology - AP Environmental Science

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.

The correct answer is genetic drift. This is the only answer choice that refers to random, natural process by which allele frequencies are reduced in general populations. All the other terms are events that occur in response to small population sizes or colonization.

Heavy decomposition of plant and animal matter contribute to highly acidic soil in tropical rainforests. Additionally, abundance of plant life in tropical rainforests results in "soil leaching," which means that the nutrients in the soil are drained and taken up by the plants themselves.

Boreal forests have extremely low temperatures and are characterized by pines and other evergreens. "Temperate forests" are characterized by moderate and more fluctuating temperatures, whereas the taiga stays cold year round. Taiga is found in parts of the world such as Northern Alaska, Canada, and Siberia.

Top predators will generally never "grow unchecked". By the very nature of their diet (dependent on other populations), predator population growth is limited by the availability of their food. The famous study of lynx-hare population fluctuations demonstrates how a predator population will adjust to lower prey populations.

Latitude is not considered in climate evaluations; for instance, the poles are considered deserts based on their precipitation levels per year, meaning deserts can occur along the equator or the poles. Temperate and tropical forests also exhibit similar precipitation levels, but due to their temperature differences, they are considered separate biomes.

Though grasslands and deserts share some of these characteristics, the tundra is the only biome listed that is characterized by a short growing season, harsh winters, no trees, mostly migratory animal species, and less than 10in of rain per year.

Don't be fooled into associating moisture retention with rainforests: Those plants don't require such an adaptation since rainfall is plentiful. A subtropical desert, however, is characterized by high temperatures, very low precipitation and warm soils, and thus plants must adapt to prevent water loss.

There are many different biomes, but the main terrestrial biomes are:

1. Temperate grassland

2. Temperate forest

3. Alpine

4. Rainforest

5. Taiga

6. Savanna

7. Tundra

8. Desert

9. Chaparral

The correct response is deciduous forest **.**The unique characteristic of the deciduous forest is that the trees shed their leaves each year. Maple and Oak trees are common in this biome. Prairie grasslands do not contain trees, rather they contain fields of grasses. The desert biome does not receive as much rainfall as the deciduous forest, nor does it contain many hardwood trees that shed their leaves. While the coniferous forest contains lots of hardwood trees, they very rarely shed their leaves. The coastal chaparral biome does not receive as much rainfall, and is dominated by small trees and shrubbery.

Humidity, atmospheric pressure, and wind are all aspects of climate but not the determining factors. In the higher latitudes, temperature is the more important factor. In the lower latitudes, precipitation is the more important factor.

The correct response is desert. The desert environment is characterized by low rainfalls (less than 25 cm per year). They are one of the most dry biomes on the planet. The desert biome also has highly variable temperature swings, with high temperatures during the day and low temperatures at night.

Polar forests are also known as "taiga"

There is no arid forest, as most arid regions are home to mostly shrub and brush-like plants. Arid areas with trees are not dense like true forests.

Brazil, Indonesia, Peru, and Zaire contain over half of the world's tropical rainforest biome. Mexico does contain some rainforest that extends into Guatemala, but not as large an area as the other countries listed.

Boreal forest, also known as "taiga," is a biome spread across the northernmost latitudes, including Canada, Alaska, Russia, and parts of northern Europe. It is characterized by coniferous forests and generally low temperatures.

A secondary consumer is a step above the primary consumer (herbivore) on the food chain, consisting of omnivores and carnivores. A mouse that lives off plant matter and is thus a primary consumer. When a snake eats the mouse, it is the secondary consumer in the food web.

With every advancement in the trophic level, energy converts on a ten-to-one scale. For example, ten kilograms of grain fed to a steer produces roughly one kilogram of beef. This is true for every step up the tropic food pyramid.

The food web is a complex feeding relationship within a community including many organisms at various trophic (feeding) levels, with many of the consumers occupying more than one level simultaneously. Herbivores (plant eaters), Carnivores (meat eaters), omnivores (Latin, "eating all), detritus feeders (debris eaters) and decomposers (bactetia and fungi) are all part of the food web. A food chain illustrates who feeds on whom in a community in a linear feeding relationship. A food chain identifies a representative of each trophic level that eats the representative of the level below it. During the carbon cycle, carbon is captured from the atmosphere during photosynthesis and passed up through the trophic levels. It is released during respiration from all trophic levels and by the burning of forests and fossil fuels. The Krebs cycle is a series of reactions occurring in the mitrochondria in which ATP is formed, which is the major energy carrier in cells. An energy pyramid is a graphical representation of the energy contained in succeeding trophic levels, with maximum energy at the base and steadily diminishing amounts at higher levels.

An energy pyramid shows maximum energy at the base and steadily diminishing amounts at higher levels. The predominant organisms in an ecosystem are plants. Plants have the most energy available to them, because they trap it directly from sunlight. Far more people can be fed on grain than on meat. Primary consumers (herbivores) that feed on plants store less energy. Secondary consumers that feed on the primary consumers store even less energy and tertiary consumers (usually carnivores) store even less. Decomposers liberate nutrients for reuse that return to the atmosphere, soil, and water.

Umbrella species are very similar to a keystone species; however, an umbrella species refers to a species that indirectly protects many other species of its ecological community during conservation. Usually, umbrella species are migratory or require a large habitat.