Question 1

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.

Accepted Answer

Net primary productivity is the amount of energy that is left after primary producers use some of the energy produced through photosynthesis for their own respiration. Therefore, the energy lost through respiration by primary producers must be subtracted in order to calculate net primary productivity. Energy lost through dead or inedible plant tissues, respiration by primary consumers, and inefficiencies of photosynthesis are not included in the calculation of net primary productivity.

Question 2

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.

Accepted Answer

Leibig's "Law of the Minimum" states that a single soil nutrient typically limits primary productivity. This means that even if all other soil nutrients are abundant, the one that is in the shortest supply will limit the rate of growth and productivity of a plant or ecosystem.

Question 3

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.

Accepted Answer

Gross primary production (GPP) is the total amount of organic matter produced by plants through photosynthesis. However, not all of this matter is available for growth and reproduction because the plant itself needs some of the energy it produced for its own respiration. Respiration is the process by which organisms break down organic molecules to release energy for cellular processes. Net primary production (NPP) is therefore defined as the amount of organic matter generated by plants that is available for consumption and growth by herbivores. It is calculated by subtracting the amount of energy used by plants for respiration (RESP) from the amount of energy produced through photosynthesis (GPP). Therefore, NPP = GPP - RESP, making choice C the correct answer.

Question 4

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.

Accepted Answer

The trophic cascade hypothesis suggests that consumers such as herbivores and predators play a strong role in controlling primary productivity. This is because their consumption of primary producers can have indirect effects on the rest of the ecosystem, leading to cascading effects throughout the food web.

Question 5

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.

Accepted Answer

The low productivity of arctic tundra ecosystems is due to a combination of factors including low evapotranspiration, which limits the availability of water, and low-nutrient soils, which limit the availability of essential nutrients for plant growth. These conditions together contribute to the overall low productivity of these ecosystems.

Question 6

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

Accepted Answer

Actual evapotranspiration rates are highest in warm, moist climates because the combination of high temperatures and abundant moisture creates ideal conditions for plants to transpire water and for water to evaporate from the soil and other surfaces. Cold temperatures and dry climates limit the availability of water and thus reduce evapotranspiration rates.

Question 7

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.

Accepted Answer

The answer of In Stephen Carpenter and colleagues' manipulations of...

Question 8

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.

Accepted Answer

Nitrogen stable isotopes change in predictable ways across trophic levels, with each level showing an increase in the δ15N value. Additionally, nitrogen isotopes vary among different food sources, allowing researchers to determine the relative contribution of different prey items to a consumer's diet. Therefore, D is the correct answer as it accounts for both of these factors. Option C is incorrect because the isotope ratio of a predator is not an exact match to its prey, but rather is slightly enriched.

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

Accepted Answer

The large grazing mammals of the Serengeti plain consume about 66% of the total primary production. This is because they are the primary consumers in the food chain and occupy a trophic level that allows them to harvest a significant amount of energy from the available plant biomass.

Question 10

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.

Accepted Answer

Studies at Hubbard Brook Experimental Forest have shown that approximately 2% of available solar energy is fixed by primary producers through photosynthesis. The rest is reflected or absorbed by other components of the ecosystem, such as the soil or water.

Question 11

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.

Accepted Answer

The increase in ¹³C content of human collagen in eastern North America is likely due to an increasing consumption of corn, which is known to have high levels of this carbon isotope. This increase likely reflects the growing importance of corn in the diet of these populations around 1,000 years ago.

Question 12

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.

Accepted Answer

Nutrients, specifically nitrogen and phosphorus, are the main limiting factors for primary productivity in lakes. When these nutrients are abundant, algae and other producers can grow rapidly, leading to higher primary productivity. Light, temperature, and pollutants can also have an effect, but nutrients are the primary factor.

Question 13

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.

Accepted Answer

The answer of The major source of nutrients in surface...

Question 14

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.

Accepted Answer

The answer of In Hubbard Brook Experimental Forest,the largest "standing...

Question 15

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

Accepted Answer

The term "primary production" specifically refers to the production of new organic matter by autotrophs in a system. This is an important concept in ecology and is often used to quantify the productivity of different ecosystems. Choices B, C, D, and E are not commonly used terms in ecology and do not accurately describe the production of organic matter by autotrophs.

Question 16

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.

Accepted Answer

Experimental fertilizations in the Baltic Sea have indicated that primary productivity there is typically limited by nitrogen.

Question 17

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.

Accepted Answer

Warm and wet environments are typically areas with high primary production due to the abundance of water and warmth, which are essential for plant growth. These conditions promote photosynthesis and provide sufficient energy for plant growth. Additionally, the high temperatures allow for decomposition processes to occur faster, promoting the recycling of nutrients in the soil, which are essential for plant growth.

Question 18

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

Accepted Answer

Trophic level refers to an organism's position in a food chain or food web based on its feeding habits. It is determined by the organism's source of energy and the number of energy transfer steps from the primary producers at the base of the food chain to the top predators at the apex.

Question 19

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.

Accepted Answer

Secondary consumers are carnivores that feed on herbivores or on detritivores. Primary consumers are herbivores that feed on primary producers. Parasitoids are organisms that lay their eggs in or on another organism, ultimately causing the death of the host. Keystone species are species that have a disproportionate effect on their environment relative to their abundance, and while they may be carnivores, their feeding habits do not dictate their classification as a keystone species.

Question 20

"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.

Accepted Answer

Actual evapotranspiration refers to the total amount of water that evaporates from the soil and is transpired by plants. Therefore, option D is the correct choice as it includes both the evaporation from the soil and the transpiration by plants. Option A refers only to water that is taken up by plant roots, while option B refers only to evaporation from soil. Option C refers only to transpiration by plants, and option E is not an accurate description of actual evapotranspiration.

Quiz 18: Primary Production and Energy Flow

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

Leibig's "Law of the Minimum" stated that

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

The "trophic cascade hypothesis" emphasizes the role of

The low productivity of arctic tundra ecosystems results

Actual evapotranspiration rates are highest in ____________ climates.

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

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

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

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

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

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

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

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

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

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

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

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

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

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