Food Webs and Pyramids - AP Environmental Science

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.

Deer, beavers, and squirrels are all primary consumers. This means that these organisms are herbivores—they only consume plants. Worms are detritivores, which eat decaying organic matter (e.g. dead animals or plants).

Biomagnification is also known as bioamplification. It occurs when the amount of environmental toxins increases as consumers move up trophic levels. For example, DDT was used to control pests. Many bird species suffered from biomaginfication and died due the amplification of the toxin levels in their systems that resulted from the consumption of multiple insects exposed to DDT.

Only three of the answer choices represent actual types of food webs: connectedness, energy flow, and functional. Connectedness webs are the type of food web used to represent feeding relationships. In short, they show relationships between predators and their prey.

Biomagnification is the process whereby the tissue concentrations of a contaminant increase as it passes up the food chain through multiple trophic levels. The contaminant is accumulated as it ascends the ecological food chain by transfer of residues from the diet into body tissues (sometimes referred to as 'bioaccumulation').

The ascension of toxic compounds through the food chain does not depend on slow to rapid change like a threshold effect, not does it involve cooperation between organisms like synergism. Compound contamination refers to contamination of the environment itself, and carcinogenesis refers to the initial formation of cancer, not the spread of contaminants.

From one trophic level to the next, only 10% of energy is transferred. The other 90% is lost through metabolic processes, like heat. This means that for every 10,000 kcal produced by producers, a tertiary consumer (three trophic levels above) will only receive 10 kcal.

Secondary productivity is the biomass accumulation of all levels of consumers. Herbivores and Carnivores are always grouped together in terms of productivity. The productivity of plants and their biomass due to photosynthesis is Primary productivity. The total biomass of an ecosystem is the sum of Primary and Secondary productivity.

The correct response is primary consumer. The primary consumer is any organism that eats autotrophs (photosynthetic organisms). A secondary consumer feeds on the primary consumer, and so on and so forth.

The correct response is **detritivore.**Organisms classified as detritivores break down organic matter from dead animals and leaves. Primary consumers feed on autotrophs, and secondary consumers feed on primary consumers. Carnivores primarily eat meat. While detritus does contain animal matter, it also contains plant and microbial matter that carnivores tend not to eat.