Ecology - AP Biology

An alternative source of naturally occurring nitrogen in ecosystems is bedrock. Bedrock is nitrogen rich and can be broken down to act as a nitrogen source.

The marine nitrogen cycle is very similar to the terrestrial nitrogen cycle. In marine ecosystems, atmospheric nitrogen enters the cycle through precipitation.

Primary succession occurs in an environment without previous life, or a barren habitat. Secondary succession occurs in an area that had previously been inhabited but experienced a disturbance, such as a wildfire. In this scenario, there still would be soil.

Primary succession occurs in an environment without previous life, or a barren habitat. The first organisms to grow (called pioneer species) are fast growing, hardy species.

Human activities such as chemical fertilizers, industrialization, and pollution significantly increase the amount of nitrogen that is biologically available in an ecosystem.

An alternative method of nitrogen fixation is a lightening strike; however, this is rare and soil-dwelling bacteria perform most of the Earth’s nitrogen fixation.

The correct answer is “all of these.” The water cycle can be broken down to three stages. The three stages of the water cycle are evaporation, condensation, and precipitation.

During the water cycle, water can take three forms: liquid, solid, and gas.

Human activity has a large impact on eco-chemical cycles, including the water cycle. Human activities that impact the cycle include agriculture, industry, and deforestation.

Heterotrophs are the consumers of the biosphere in that they do not produce organic material but rather consume other organisms. Animals are an example of heterotrophs. Autotrophs produce their own organic material from inorganic materials. Plants are an example of autotrophs.

Animals are a type of heterotrophs. Heterotrophs are unable to make their own organic materials and so they must consume other organic materials in the form of autotrophs and other heterotrophs.

Carnivores are organisms that consume meat—animal tissue—as a part of their diet; therefore, on the food chain, carnivores may occupy the secondary, tertiary, or quaternary consumer levels.

Endotherms maintain a relatively constant body temperature, independent of their external environment. They can shiver when cold to increase their body temperature through expending energy (“shivering thermogenesis”).

An ectotherm relies on external sources to regulate its body temperature. Endotherms maintain a relatively constant body temperature, independent of their external environment. To regulate their body temperature, endotherms have a higher

Invasive species are organisms that become established outside their native range. In this example, the seed’s native range is the countryside. However, when it is carried by the wind to the forest (an environment outside its native range), it plants itself and establishes a population there. The seed is an example of an invasive species.

The population density is the measure of the population per unit area or volume, and may be measured over land or water.

The carrying capacity refers to the maximum number of organisms that can be sustained by the resources of an environment. The range of a population is simply the area over which the population can be found. Dispersion refers to the different regions where a species is found within a given area. Competition is the use of limited resources between multiple members of a population, or multiple species within a niche.

The earth's habitats and ecosystems are dispersed based on air circulation, rainfall, and topography. For example, when looking at the globe, we may notice that the world's major grasslands are always leeward of major mountain ranges, or that tropical rain forests are located around the equator. Why do grasslands fall on the leeward side of mountain ranges, and tropical rainforests at the equator? As the air travels up the mountain, it condenses and precipitation occurs. Once the air reaches the leeward side, it is dry, resulting in the grasslands and plains. Tropical rainforests are located at the equator, an area that gets constant sunlight and rainfall regardless of the earth's tilt. The dispersion of the earth's habitats and ecosystems is very dependent on such environmental factors.

A community is a group of populations of different species but live in the same area and interact. Community interactions may display interspecific interactions such as competition, predation, herbivory, symbiosis, or facilitation. A population is a group of organisms of the same species that live together and interact.

Competitive exclusion is when an inferior competitor is eliminated. In the moss example, the moss that is able to use resources more efficiently and reproduce quicker will beat out the less competitive moss. An ecological niche is the sum of a species’ use of the biotic and abiotic resources in its environment. Resource partitioning is the differentiation of niches that allows similar species to coexist in a community. If one of the mosses could adapt to use different resources, the two species could coexist together. Character displacement has to do with speciation. It refers to the tendency for character traits to diverge more in sympatric populations rather than allopatric populations.

Species diversity is the variety of organisms that make up a community. There are two parts of species diversity: species richness and relative abundance. Species richness refers to the number of different species in the community. In this example, forest 1 has greater species richness and diversity over forest 2.