Ecology Ch. 18

When determining an organism’s trophic level, what group is used as the start of the transfer of energy? Primary producers

Identify the two key variables that are correlated with variation in terrestrial primary production. Temperature, moisture

Which nutrient is the limiting factor for marine ecosystems? Nitrogen

Rank the order of events that occurred when the levels of planktivorous fish was reduced in a lake. The predaceous invertebrate population increased. The herbivorous population shifted to larger individuals. The herbivorous population fed upon the phytoplankton. The phytoplankton biomass and rate of primary production declined.

What mechanisms underly compensatory growth? A reduction in self-shading. Lower rates of respiration.

Ecosystem often have more than ten trophic levels. FALSE

What is the typical range of energy being transferred during ecological efficiency? 5 to 20%

Which environmental conditions would most likely produce the highest primary productivity? Warm and moist

What are the effects of a trophic cascade? A change in the abundance of biomass. A decrease in the prey diversity. A change in the productivity of a population.

When studying ecosystems, Arthur Tansley realized the importance of considering organisms and their environment as what type of system? Integrated

What event would cause plants to undergo compensatory growth? Grazing by herbivores

In what ways is energy lost in ecosystems? Limited consumption. Respiration by consumers. Heat production.

Which of the following is a type of top-down control on ecosystems? Type of predators

Which organisms are responsible for primary production? Autotrophs

Rank, in order with the first change at the top, the events that would occur in a lake ecosystem if the biomass of planktivorous fish increased. Zooplankton biomass would decrease. Average size of herbivorous zooplankton would decrease. Phytoplankton biomass would increase. Primary production would increase.

Which of the following factors are bottom-up controls of ecosystems? Chemical factors, physical factors

Identify the best description of trophic dynamics. The transfer of energy from one part of an ecosystem to another.

List in order, with the highest consumer at the top, the steps of a trophic cascade in a freshwater lake. Piscivore fish feed on planktivorous fish. Planktivorous fish feed on zooplankton. Zooplankton feed upon phytoplankton. Phytoplankton determine the biomass level.

In what trophic level are detritivores placed? Second

What happens to sunlight as it shines upon a forest? It is reflected from the forest canopy. It is converted into heat.

In which aquatic ecosystem is nitrogen the limiting nutrient for phytoplankton biomass? Ocean

Which nutrient was determined to be a limiting factor in the biomass of phytoplankton? Phosphorus

How is annual actual evapotranspiration measured? The total amount of water that evaporates and transpires during the course of a year

Identify the bottom-up control. Average temperature

In what way do land-based nutrients enter the ocean ecosystem along continental margins? Runoff

Which influences on grassland ecosystems are produced by grazing mammals? Soil fertility, plant production

Which organism would directly use the biomass produced by forest vegetation? Rabbit

What happens to energy as it is transferred from one trophic level to the next? Some is lost

Which organism would most likely contribute to a trophic cascade? Grey wolf

Which statement best fits the definition of primary production? Production of new organic matter by autotrophs

What are the various forms of energy for consumers in a salt marsh? Detritus, phytoplankton, upland plants

In which trophic level are the carnivores that feed upon herbivores placed? Third

When studying trophic dynamics, what is the key component that is being discussed? Transfer of energy

What is the correct relationship between phosphorus and plankton biomass? High phosphorus equals high phytoplankton biomass

What is the limiting factor in all ecosystems that determines the number of trophic levels present? Amount of available energy

Which type of primary production is a measure of the total amount of biomass produced by all of the autotrophs? Gross

Identify the top-down control. Red tailed hawk

Which states had the highest net primary productivity in the central grassland region of the United States. Mississippi, Arkansas

Which ecosystem components are studied by an ecosystem ecologist? Flow of water; flow of nutrients; flow of energy

Which regions of the ocean have the highest net primary productivity? Areas of upwelling; margins of the continents; areas over continental shelves

Ecosystems often have more than ten trophic levels. FALSE

Which isotopes were used by Peterson in order to determine the food sources used by mussels in the salt marsh? Carbon; sulfur; nitrogen

Which soil nutrients play the greatest role in determining terrestrial primary productivity? Phosphorus, nitrogen

Which statement describes Liebig’s Law of the Minimum? A single nutrient controls primary productivity

What percentage of primary production are grazers responsible for consuming on the Serengeti grasslands? 66%

Which region of the ocean will have the highest net primary productivity? Over continental shelves

What information did Peterson gain during his salt marsh study by investigating the ratios of stable isotopes? The contribution of alternative food sources to the diet of the mussel

Which nutrients were added to the Alaskan tundra during the Shaver and Chapin study? Phosphorus; nitrogen; potassium

How is the rate of primary production measured? Amount of biomass / interval of time

Which nutrient was found to be a limiting nutrient only in the wet meadow? Phosphorus

Which nutrients produce an increase in phytoplankton biomass in an aquatic ecosystem? Sucrose; nitrate; carbon

Identify the minimum increase in net primary production at the Shaver and Chapin study sites. 23%

Which two ecosystems would have the lowest AET levels? Hot desert; tundra

Which factor, suggested by Dillon and Rigler, is believed to influence phytoplankton biomass? Intensity of predation on the zooplankton

Identify the biome that has the greatest net primary productivity. Temperate deciduous forest

Which ingredient is not required for carbon fixation to occur? O2

Which nutrient proved to be a limiting factor in the phytoplankton biomass in lake ecosystems? Phosphorus

Which variable helps explain the difference in terrestrial primary productivity of the same type of ecosystem? Soil fertility

What is the scatter of points around lines showing a relationship between nutrient concentrations and phytoplankton biomass called? Residual variation

Identify the different ways in which primary production is measured. The levels of oxygen production by primary producers; the amount of biomass produced by producers; the rate of carbon uptake by primary producers

Recognize which statement describes the process of carbon fixation. PAR converts CO2 into sugar and other biomass

Identify the maximum increase in net primary productivity at the Shaver and Chapin study sites. 300%

Which nutrient is considered the main nutrient that limits net primary production? Nitrogen

What would occur to the phytoplankton biomass of a lake if a large amount of phosphorus was added? The biomass would increase

During the salt marsh study which group of producers were the most depleted of 13 C? upland plants

What is one of the main ways in which primary production is measured? The rate of carbon uptake by primary producers

Which ecosystem would you predict would have the highest AET? Jungle

Which nutrient combination increased the phytoplankton biomass the most? Carbon, nitrate, and phosphate

How much did the primary production increase when only nitrogen was added to the dry alpine meadow? 63%

What is the main source of nutrient renewal in the open ocean? Vertical mixing

How did Lake 226 respond once the fertilizer was no longer being added? The biomass declined

Which type of grazing pattern resulted in compensatory growth of the plants? Intermediate intensity

What feature prevents the open ocean from experiencing a significant amount of vertical mixing? A permanent thermocline

How did Lake 226 respond to the addition of nutrients? The biomass increased

Which combination of fertilizers produced a 178% increase in primary production of the dry alpine meadow? Nitrogen and phosphorus

Why does heavy grazing not result in compensatory growth of plants? It reduces the plants capacity to recover