Exam 57: Ecosystems

A segment of a food web includes the following interactions: In this example, _______ has the lowest trophic efficiency, and the _______ level supports the lowest biomass.

Agricultural researchers are interested in the effect of production efficiency on economic impacts, sustainability, and production of greenhouse gases by cattle.Two groups of cattle were fed different diets.One group was fed exclusively on grass.The other was fed an energy-rich diet that included grain supplements.How would the two diets most likely affect production efficiency of the cattle?

Which of the following would be considered an ecosystem service?

The current cost of water treatment represents approximately 50 percent of the cost currently paid for water by residents in the city of Vancouver, Canada.Experts estimated that water treatment costs would increase by up to $0.82 per cubic meter if forest and wetland areas declined by 10 percent.This information suggests that

Pacific salmon swim up freshwater rivers to breed.The watershed uphill from the rivers is forested and drains into freshwater streams where the salmon spawn and their young offspring live and grow.Managers calculated that degradation of a specific watershed from its pristine condition resulted in a loss of value of $1.6 million, yet the land was sold for $1 million to developers.This suggests that

Runoff from excess nitrogen fertilizer applied to agricultural land leads to overfertilization of water bodies, which leads to a process called _______.

Pyramid diagrams show the proportion of the energy transferred from one trophic level to the next higher trophic level.This value is calculated by dividing the amount of energy at one trophic level by the amount of energy at the trophic level immediately below it.This value is called the _______.

Two important marine food webs off the west coast of North America are the phytoplankton  zooplankton  fish web and the kelp  sea urchin  sea otter web.How do these two food webs compare in terms of the primary control of energy flow?

Grizzly bears eat a variety of both plants (grasses, roots, and berries) and animals (insects, rodents, and fish).How would the NPP of a three-level food web containing grizzly bears compare to the NPP of a three-level food web having no grizzly bears or other omnivores?

Ecosystem services are often undervalued or ignored when social and economic decisions are made.A major reason for this is that ecosystem services

In a biogeochemical cycle, large amounts of an element can be stored for millions of years and remain relatively untouched.Which is the best example of such a pool?

The way energy flows through ecological communities is different from the way nutrients flow through ecological communities because

In a major upwelling region in the eastern equatorial Pacific Ocean, nutrient availability tends to be relatively high, compared with other parts of the ocean.Shortly after an upwelling event, nutrients including nitrogen, carbon, and phosphorus increased, and the region had a short-term phytoplankton bloom.The bloom then stopped until an iron compound was added artificially.This indicates that the region was limited by

Compare the climates in two African ecosystems: the tropical rainforest and the Sahara.The rainforest has a very high rainfall and high biomass of trees and other vegetation.The Sahara is a desert and has extremely low rainfall and almost no vegetation.In these two ecosystems, which processes of the hydrologic cycle would be expected to predominate?

Organisms in an estuary, including phytoplankton, seagrasses, crustaceans, and mollusks, are all exposed to increasing acidity as atmospheric CO₂ levels rise.What effect does the increased acidity likely have on these organisms?

Which statement best explains why sustainable ecosystems are still needed in our increasingly technological society?

Which factor is least likely to have an effect on the total number of trophic levels in an ecosystem?

The experiments of David Schindler and colleagues showed that phytoplankton and cyanobacteria blooms were triggered in Canadian lakes by the addition of the nutrient _______.

Carbon sequestration, or removing carbon from the atmosphere and storing it in pools where it will remain long term, is frequently suggested as one possible way to remove excess greenhouse gases causing global warming.This is an example of a type of ecosystem service called a(n) _______ service.

Rising CO₂ levels have many effects on Earth's ecosystems and organisms.Which effect would have the most immediate impact on Arctic organisms?