Deck 56: Dynamics of Ecosystems

Question 1

Even though nitrogen constitutes 78% of Earth's atmosphere,the amount available for living things nearly all comes from

A)a few groups of nitrogen-fixing bacteria.
B)the breakdown of minerals.
C)a few genera of detritivores.
D)the breakdown of dead plants.
E)nitrogen-containing fertilizers.

Answer 1

A

Question 2

Over tropical rainforest areas,approximately 90% of the water that reaches the atmosphere comes from

A)animal metabolism.
B)animal perspiration.
C)plant transpiration.
D)plant absorption.
E)plant metabolism.

Answer 2

C

Question 3

In which of the following ways does species richness affect ecosystem function? Check all that apply.

A)Low species richness can contribute to ecosystem stability.
B)High species richness can increase ecosystem resistance to drought.
C)Low species richness can make an ecosystem more susceptible to invasive species.
D)High species richness reduces overall ecosystem productivity.

Answer 3

B,C

Question 4

The form of nitrogen most likely to be absorbed from the soil by plants is

A)nitrogenous wastes.
B)nucleic acids.
C)nitrogen gas.
D)nitrous oxide gas.
E)nitrite/nitrate ions.

Question 5

The honey possum (Tarsipes rostratus)is a tiny Australian marsupial that feeds entirely on nectar.Which of the following terms describes the role of a honey possum in its ecosystem?

A)herbivore
B)primary producer
C)primary carnivore
D)secondary carnivore
E)detritivore

Question 6

The balance between photosynthesis and ________ is altered by the combustion of fossil fuels.

A)respiration
B)sunlight
C)growth
D)decomposition

Question 7

A wolf that feeds on moose and elk would be classified within which trophic level?

A)herbivore
B)primary producer
C)primary carnivore
D)secondary carnivore
E)detritivore

Question 8

Vampire squid (Vampyroteuthisinfernalis)are deep-sea cephalopods with features similar to both octopus and squid.Extensive video recordings show the diet of the vampire squid consists of items like crustacean remains and fecal pellets.Which of the following terms describes the position of the vampire squid in the deep-sea trophic pyramid?

A)herbivore
B)primary producer
C)primary carnivore
D)secondary carnivore
E)detritivore

Question 9

In the carbon cycle,________ from the atmosphere is used in photosynthesis to synthesize carbon-containing organic molecules in a process called ________.

A)carbon dioxide; combustion
B)carbon dioxide; carbon fixation
C)hydrocarbons; oxidation
D)hydrocarbons; cellular respiration

Question 10

Which of the following are true about ecosystems? Check all that apply.

A)They contain both living and nonliving components.
B)There is a transfer of energy through the system and some energy is lost as heat energy.
C)Nutrients repeatedly cycle through the ecosystem.
D)They represent the lowest level of biological organization.
E)The ultimate source of energy for most ecosystems is the sun.

Question 11

Only about ________ of the sunlight falling on plant leaves is captured by photosynthesis.

A)1%
B)10%
C)25%
D)50%

Question 12

With almost no exceptions,the nitrogen fixers are

A)beans.
B)green plants.
C)insects.
D)mammals.
E)prokaryotes.

Question 13

Solar energy is the same thing as heat energy.

Question 14

A(n)________ is a permeable underground layer of rock,sand,and gravel saturated with groundwater.

A)natural spring
B)aquifer
C)hot spring
D)submergence

Question 15

NPP is the difference between plant photosynthesis and respiration.Therefore,NPP quantifies the net absorption of what element(s)by living plants?

A)carbon
B)phosphorus
C)nitrogen
D)oxygen
E)nitrogen,phosphorus,and potassium

Question 16

Which of the following biogeochemical cycles contain a mineral component?

A)phosphorus
B)carbon
C)nitrogen
D)oxygen
E)water

Question 17

Which of the following atmospheric gases is changing the global climate?

A)ozone
B)water vapor
C)carbon dioxide
D)hydrogen
E)oxygen

Question 18

Heterotrophs must obtain organic molecules that have been synthesized by

A)biogeochemical cycles.
B)bacteria.
C)decomposers.
D)autotrophs.

Question 19

The upper,unconfined portion of the groundwater constitutes the ________,which flows into streams and is partly accessible to plants.

A)aquifer
B)hydrozone
C)water table
D)watershed

Question 20

A ________ cycle is a cyclic path that involves both biological and chemical processes of an ecosystem.

A)biogeochemical
B)complete
C)hydrological
D)complementary

Question 21

Which of the following groups do not contain any species that are autotrophs?

A)Bacteria
B)Protista
C)Plants
D)Archaea
E)Fungi

Question 22

Addition of a primary carnivore to an ecosystem can sometimes influence the whole ecosystem.This process is called

A)ecosystem stabilization.
B)a bottom-up effect.
C)species turnover.
D)disruption.
E)a trophic cascade.

Question 23

What feature do the carbon and nitrogen cycles have in common?

A)a large atmospheric component
B)involvement in global climate change
C)often a limiting nutrient
D)mostly local cycling
E)many microbes involved in cycling

Question 24

Energy enters most ecosystems by the process of

A)biosynthesis.
B)respiration.
C)biogeochemical weathering.
D)photosynthesis.
E)fermentation.

Question 25

During the 1960s,a group of scientists in the northeastern United States conducted an experiment at Hubbard Brook,New Hampshire.A 38-acre watershed was completely deforested and the runoff (water flow)monitored for several years.It was compared to an adjacent watershed that was left untouched.The scientists collected data during those years and found

A)no difference in the amount of runoff from the two areas.
B)an insignificant difference in the amount of nitrogen from the two areas.
C)a tremendous increase in the total amount of runoff from Hubbard Brook although the loss of nitrogen was fairly consistent in both areas.
D)a tremendous increase in the amount of runoff and nitrogen release from Hubbard Brook compared to the control.

Question 26

Which one of the following quantities best represents the respiratory heat lost by plants in an ecosystem?

A)gross primary productivity
B)net primary productivity
C)gross primary productivity - net primary productivity
D)gross primary productivity - standing crop biomass
E)gross primary productivity - secondary productivity

Question 27

The scarcity of which two elements limits plant growth?

A)oxygen,nitrogen
B)nitrogen,phosphorus
C)oxygen,phosphorus
D)carbon,nitrogen
E)carbon,phosphorus

Question 28

In an ecosystem

A)both energy and nutrients cycle.
B)energy flows and nutrients cycle.
C)energy cycles and nutrients flow.
D)both energy and nutrients flow.
E)energy is contained with nutrient cycles.

Question 29

The rate of production of new biomass by heterotrophs is called

A)secondary productivity.
B)primary productivity.
C)consumer productivity.
D)gross productivity.
E)net productivity.

Question 30

Which one of the following ecosystems is most likely to show an inverted biomass pyramid but a normal energy pyramid?

A)grassland
B)open ocean
C)intertidal
D)tropical forest
E)desert

Question 31

In the food chain below,what does the garden spider represent? crabgrass-cricket-garden spider-blue jay-red-tailed hawk

A)herbivore
B)primary producer
C)primary carnivore
D)secondary carnivore
E)detritivore

Question 32

The net weight of all of the organisms living in an ecosystem is its

A)productivity.
B)biomass.
C)vital force.
D)photosynthesis minus metabolism.
E)combined output of metabolism and photosynthesis.

Question 33

A Viceroy caterpillar feeds on a leaf.One day's feeding consumes 1000 calories worth of leaves.50% of the calories are lost in its feces and 33% of the calories are used in cellular respiration.How many calories of the original intake are available to add to the caterpillar's biomass each day?

A)830 calories
B)670 calories
C)500 calories
D)330 calories
E)170 calories

Question 34

In an ecosystem,the amount of organic matter produced in a given time that is available for heterotrophs is known as

A)daily yield.
B)gross primary productivity.
C)net primary productivity.
D)effective vitality.
E)net yield.

Question 35

In the food chain below,what does the blue jay represent? crabgrass-cricket-garden spider-blue jay-red-tailed hawk

A)herbivore
B)primary producer
C)primary carnivore
D)secondary carnivore
E)detritivore

Question 36

In a food chain with four trophic levels,what would be the energy in the top trophic level if the energy contained in the primary producer level is 40,000 kcal/m²/yr? Assume a trophic level transfer efficiency of 10%.

A)4,000 kcal/m²/yr
B)400 kcal/m²/yr
C)40 kcal/m²/yr
D)4 kcal/m²/yr
E)0)4 kcal/m²/yr

Question 37

In a marine ecosystem with an inverted biomass pyramid,which trophic level should have the smallest number of organisms?

A)phytoplankton
B)zooplankton
C)primary carnivores (sardines)
D)secondary carnivores (tuna)
E)detritivores

Question 38

The following figure shows studies in a stream where enclosures were set up either with trout or with no trout.Which statement is a correct interpretation of the graph about trout,invertebrates,and algae?

A)If trout are present in a system,algae production is low and invertebrate population levels are also low.
B)If trout are present in a system,algae production is high and invertebrate population levels are also high.
C)If trout are present in a system,algae production is high and invertebrate population levels are low.
D)Trout do not seem to affect the algae production; only the invertebrate populations are affected.
E)Trout do affect the algae production but not the invertebrate populations.

Question 39

Which one of the following factors would NOT influence the productivity of an ocean community?

A)the presence of nitrogen-fixing cyanobacteria
B)the season of the year
C)levels of autotrophs
D)fertilizer runoff
E)the amount of rainfall

Question 40

A good average value for the amount of energy that reaches the next trophic level is about

A)20%.
B)10%.
C)5%.
D)2%.
E)1%.

Question 41

In an aquatic ecosystem,a secondary carnivore is temporarily excluded and then,after a period of time,is returned.Which one of the following is NOT an expected top-down effect after it is returned?

A)Primary carnivores become less abundant.
B)Primary productivity increases.
C)Algae decrease.
D)Herbivores become more abundant.

Question 42

Which of the following observations were an outcome of studies by David Tilman and coworkers at Cedar Creek,Minnesota on ecosystem stability? Check all that apply.

A)Plots with more species showed less year-to-year variation in biomass.
B)Species-rich plots were less affected by drought than species-poor plots.
C)Over-yielding was observed in more recent work at Cedar Creek.
D)Nitrogen uptake and total biomass produced were negatively correlated to species richness.
E)More diverse plots were less susceptible to invasion by new species.

Question 43

Which of the following are true statements about the carbon cycle? Check all that apply.

A)Carbon and nitrogen fixation are both facilitated by microbes.
B)Burning of gasoline is a contributor to the current imbalance in the carbon cycle.
C)Replacing rainforest with farms decreases atmospheric CO₂ levels.
D)In water,inorganic carbon exists in two different forms,both of which can be used by autotrophs.
E)Carbon cycles locally.

Question 44

Phosphorus deficiency often appears early in plant growth and results in stunting.Which of the following are reasons why a deficiency in phosphorus would cause growth abnormalities in plants? (Check all that apply.)

A)Phosphorus is required for the storage and transfer of energy.
B)Phosphorus is required for the production of amino acids that form proteins.
C)Phosphorus is required for DNA replication.
D)Phosphorus is necessary for building molecules in the cell membrane.
E)Without phosphorus,cellular replication is impeded.

Question 45

Which one of the following statements about the trophic cascade in the sea otter and sea urchin-kelp communities along the West Coast of North America are true? Check all that apply.

A)Increased sea otter populations are linked to more profuse growth of the kelp forests.
B)Increased orca (killer whale)predation on sea otters is linked to more profuse growth of the kelp forests.
C)Increased sea otter populations are linked to increased sea urchin populations.
D)Increased orca (killer whale)predation on sea otters is linked to increased sea urchin populations.
E)Increased sea urchin populations are linked to less profuse growth of the kelp forests.

Question 46

Which of the following hypotheses support the basic principle of the species-area relationship? Check all that apply.

A)Large areas have greater habitat diversity than small areas.
B)Organisms are less likely to go extinct in larger areas than smaller areas.
C)Larger areas receive more colonists than smaller areas.
D)Smaller areas have greater concentrations of resources then larger areas.

Question 47

The tropics are known to have greater species diversity than the temperate zones.Which explanation for this phenomenon is the LEAST convincing?

A)Seasonal variability is less in the tropics.
B)Niches are narrower in the tropics.
C)Fewer predators in the tropics allow more prey species to flourish.
D)Greater spatial heterogeneity in the tropics creates more niches.
E)The tropics have greater plant production,which supports greater overall species richness.

Question 48

According to MacArthur and Wilson's island biogeography theory,which of the following would be expected to have the smallest species richness?

A)the mainland
B)a large island near the mainland
C)a large island far from the mainland
D)a small island near the mainland
E)a small island far from the mainland