Deck 18: Primary Production and Energy Flow

Question 1

Leibig's "Law of the Minimum" stated that

A)the lowest primary productivity occurs in the coldest ecosystems.
B)primary productivity is typically controlled entirely by climate.
C)primary productivity is typically controlled by both climate and soil nutrients.
D)a single soil nutrient typically limits primary productivity.
E)the highest primary productivity occurs at the lowest trophic level.

Answer 1

D

Question 2

An organism's _________ describes its feeding position within an ecosystem.

A)prey level
B)production level
C)consumption level
D)trophic level
E)predator level

Answer 2

D

Question 3

The major source of nutrients in surface waters of the open ocean is

A)mixing of subsurface with surface waters.
B)deposition from the atmosphere.
C)addition by ocean currents bringing nutrients from nearshore waters.
D)decomposition of dead organic material.
E)photosynthesis by planktonic algae.

Answer 3

A

Question 4

Carnivores that feed on herbivores (or on detritivores)are referred to as

A)primary producers.
B)primary consumers.
C)secondary consumers.
D)parasitoids.
E)keystone species.

Question 5

An increase about 1,000 years ago in ¹³C content of human collagen from archeological sites in eastern North America probably records

A)replacement of vegetables and grains in the diet by meat.
B)replacement of corn by beans and squash in the diet.
C)increasing consumption of corn.
D)increasing levels of ¹³C in soils.
E)increasing levels of ¹³C in the atmosphere.

Question 6

Nitrogen stable isotopes are useful tools for the study of food web structure because isotope ratios

A)change in predictable ways across trophic levels.
B)often vary among alternative food sources for a consumer.
C)for a predator exactly match the isotope ratio in its prey.
D)both change in predictable ways across trophic levels and often vary among alternative food sources for a consumer.

Question 7

Among lakes,primary productivity seems to be mainly controlled by levels of

A)light.
B)pollutants.
C)temperature.
D)nutrients.
E)None of the choices are correct.

Question 8

The "trophic cascade hypothesis" emphasizes the role of

A)nutrients in controlling primary productivity.
B)nutrients in controlling primary consumption.
C)consumers in controlling primary productivity.
D)grazing by herbivores in controlling ecosystem nutrient levels.
E)primary productivity in controlling primary and secondary consumption.

Question 9

On the Serengeti plain of eastern Africa,large grazing mammals consume what fraction of total primary production?

A)a negligibly small amount
B)about 10%
C)about 25%
D)about 66%
E)nearly all

Question 10

The low productivity of arctic tundra ecosystems results

A)entirely because tundra has low evapotranspiration.
B)entirely because tundra soils are low in nutrients.
C)entirely because tundra soils retain water poorly.
D)because tundra soils have low nutrients and retain water poorly.
E)because tundra has low evapotranspiration and low-nutrient soils.

Question 11

In Stephen Carpenter and colleagues' manipulations of lake food webs,increased densities of adult largemouth bass led to

A)increased rates of grazing on phytoplankton by zooplankton.
B)decreased rates of grazing on phytoplankton by zooplankton.
C)increased population sizes of planktivorous fish.
D)increased consumption of zooplankton by planktivorous fish.
E)no noticeable effects on food web structure.

Question 12

Which of the following is the correct relationship between gross primary production (GPP),net primary production (NPP),and respiration (RESP)?

A)GPP = NPP - RESP
B)RESP = GPP + NPP
C)NPP = GPP - RESP
D)NPP = GPP + RESP
E)None of the choices are correct.

Question 13

The production of new organic matter,or biomass,by autotrophs in a system is called ____________.

A)primary production
B)primary construction
C)trophic production
D)trophic gain
E)autotrophic gain

Question 14

"Actual evapotranspiration" for an ecosystem refers to the amount of water that

A)is taken up from soils by plant roots.
B)evaporates from soils.
C)is transpired by plants.
D)evaporates from soils plus the amount transpired by plants.
E)could evaporate from soils,if they were kept wet at all times.

Question 15

In Hubbard Brook Experimental Forest,the largest "standing stock" of energy is represented by biomass of

A)living plant tissues.
B)dead plant tissues.
C)invertebrate herbivores.
D)vertebrate herbivores.
E)vertebrate carnivores.

Question 16

The terrestrial ecosystems with highest primary production are usually those that are

A)warm and wet.
B)warm and dry.
C)cool and wet.
D)cool and dry.
E)intermediate in both temperature and moisture.

Question 17

In Hubbard Brook Experimental Forest,the fraction of available solar energy fixed by primary producers is

A)approximately 2%.
B)approximately 15%.
C)approximately 50%.
D)nearly all of it.
E)Primary producers do not fix solar energy.

Question 18

Experimental fertilizations in the Baltic Sea suggest that primary productivity there is normally limited by

A)phosphorus.
B)nitrogen.
C)iron.
D)potassium.
E)temperature.

Question 19

Actual evapotranspiration rates are highest in ____________ climates.

A)warm,moist
B)cold,moist
C)warm,dry
D)cold,dry
E)actual evapotranspiration rate is not affected by climate

Question 20

Net primary productivity is the primary productivity of an ecosystem,after subtracting energy lost in

A)dead plant tissues.
B)inedible plant tissues.
C)respiration by primary producers.
D)respiration by primary consumers.
E)inefficiencies of photosynthesis.

Question 21

Bowman and his colleagues,who added nutrients to the alpine tundra on Niwot Ridge,Colorado,found

A)phosphorus is the main nutrient limiting primary production in all meadows.
B)nitrogen is the main nutrient limiting primary production in all meadows.
C)phosphorus is the main nutrient limiting primary production in dry meadows.
D)nitrogen is the main nutrient limiting primary production in wet meadows.
E)nitrogen and phosphorus jointly limit primary production in wet meadows.

Question 22

You are comparing two population means with a Student's t-Test.If the calculated value of t is greater than the critical value of t,you accept the hypothesis which states that there is a significant difference between the population means.

Question 23

The number of trophic levels in an ecosystem is limited by

A)the number of tertiary consumers.
B)the loss of energy with each transfer between trophic levels.
C)the gain of energy with each transfer between trophic levels.
D)the rate at which organisms can recycle energy within the ecosystem.
E)the rate at which secondary consumers consume their prey.

Question 24

The total amount of energy fixed by autotrophs in an ecosystem is called ________________.

Question 25

The rate of primary production on the Serengeti grassland is positively correlated with

A)rainfall.
B)moderate grazing.
C)high-intensity grazing.
D)both rainfall and moderate grazing.
E)both rainfall and high-intensity grazing.

Question 26

The influences of nutrients and temperatures on ecosystem properties are part of what ecologists call "bottom-up controls."

Question 27

Primary producers make up the first,or basal,____________ in most food webs.

Question 28

Among marine systems,primary productivity is highest in tropical portions of the major oceans,far from terrestrial influences.

Question 29

Primary production is lowest in which ecosystem?

A)creosote bush desert
B)annual grassland
C)subalpine forest
D)temperate deciduous forest
E)tropical forest

Question 30

On the Serengeti plain of eastern Africa,intensive grazing by large mammals greatly decreases primary productivity in the grazed areas.