Deck 55: Energy Flow and Chemical Cycling in Ecosystems

Question 1

Use the figure to answer the question: Which of the following best explains why no arrows lead directly from "Detritus" to secondary consumers?

A) detritus is living organic material, and primary consumers only eat dead organisms
B) few primary consumers directly eat detritus, and so it is mostly broken down into inorganic compounds by decomposers such as earthworms, fungi, and prokaryotes
C) detritus is toxic prior to being broken down by prokaryotes and fungi
D) detritus is too small to be located by primary consumers

Answer 1

B

Question 2

Use the figure to answer the question: The blue arrow exiting the left side of the "Primary consumers" box could best be described as which of the following examples of a nutrient transfer?

A) decomposition of dead matter
B) feces excreted by the primary consumer
C) predation of the primary consumer
D) production consumed by the primary consumer

Answer 2

B

Question 3

Which of the following best represents the actions of photoautotrophs?

A) produce oxygen and use carbon dioxide
B) produce, and use, both oxygen and carbon dioxide
C) produce thermal energy to be used by other organisms
D) convert chemical energy to solar energy

Answer 3

B

Question 4

Use the following figure to answer the question. In the ecosystem figure, which component of the food web has the potential to lose the most energy as heat?

A) secondary and tertiary consumers
B) primary consumers
C) primary producers
D) microorganisms and other detritivores

Question 5

The introduction of a predator population of arctic foxes to a small island caused the grassland community of the island to slowly convert to tundra due to changes in nutrient cycling. Which of the following best explains this change in the ecosystem?

A) The grassland habitats were negatively affected by the trampling and burrow-digging of the predator population.
B) The water intake of the predator population reduced water availability for grasses.
C) The predator population consumed a large proportion of the grass-like plants.
D) The predators consumed an herbivore or secondary consumer population that was promoting grass-like habitats.

Question 6

Which of the following statements about energy is most accurate?

A) Plants reduce the amount of total energy in a system during the conversion of energy from solar to chemical forms.
B) The total amount of energy in an ecosystem changes during the process of photosynthesis and respiration as matter is lost.
C) The amount of energy stored in organic molecules must equal the total solar energy intercepted by the plant minus the amounts reflected and dissipated as heat.
D) Energy can be created, but not destroyed.

Question 7

Use the following figure to answer the question. Food web for a particular terrestrial ecosystem (arrows represent energy flow and numbers represent species)
In the food web, if species 3 is toxic to predators, then which species is most likely to benefit from being a mimic of species 3?

A) 1
B) 2
C) 4
D) 5

Question 8

Assuming it were technologically feasible, a scientist could hypothetically track the long-term fate (for example, 100 years) of every atom in a single molecule of carbon dioxide that initially moves from the air into a plant. This fact is a manifestation of which of the following physical laws?

A) conservation of energy
B) conservation of mass
C) conservation of nutrients
D) energy and chemical flow

Question 9

Which of the following components is not recycled within an ecosystem?

A) heat
B) nitrogen
C) phosphorus
D) carbon

Question 10

Which of the following are the main forms of energy inputs and outputs that move through an ecosystem?

A) soil elements, water, oxygen, carbon dioxide, chemicals within detritus (dead organisms)
B) sunlight and heat
C) inorganic and organic compounds plus solar radiation
D) water, nitrogen, phosphorus, carbon and heat

Question 11

In order to recycle nutrients, which of the following minimum components must an ecosystem have?

A) producers
B) producers and decomposers
C) producers, primary consumers, and decomposers
D) producers, primary consumers, secondary consumers, and decomposers

Question 12

Which of the following most accurately describes the fate of incoming solar radiation from the sun?

A) Most of the incoming solar radiation is transmitted through plant leaves or lost as heat.
B) A tiny fraction of the incoming solar radiation is absorbed by photosynthetic plant pigments.
C) Most incoming solar radiation strikes and is absorbed by Earth's land surfaces.
D) Solar radiation is least intense at the tropics.

Question 13

Which of the following terms encompasses all of the others?

A) heterotrophs
B) herbivores
C) carnivores
D) primary consumers

Question 14

Which of the following best explains the need for a constant influx of sunlight to sustain Earth's biosphere?

A) energy from sunlight moves through ecosystems but is lost as heat
B) energy from sunlight warms the Earth, which allows organisms to flourish
C) energy from sunlight is the primary source of chemical energy
D) energy from sunlight strikes Earth and is recycled through food webs

Question 15

Use the following figure to answer the question. Food web for a particular terrestrial ecosystem (arrows represent energy flow and numbers represent species)
Based on this food web, which species is most likely a decomposer?

A) 1
B) 2
C) 3
D) 5

Question 16

Which of the following are the two key emergent properties of an ecosystem?

A) decomposition and nutrient cycling
B) solar radiation and primary production
C) photosynthesis and cellular respiration
D) energy flow and chemical cycling

Question 17

A group of students walking through a coastal rainforest in Vietnam observe a large, beautiful tree towering above. The tree is full of orchids, mosses, birds, insects, arachnids, and millions of bacteria, all interacting with the abiotic environment, including the air, soil, and water of the forest. Which of the following terms bests describe this in the entirety of what they are observing?

A) habitat
B) microcosm
C) ecosystem
D) community

Question 18

If the sun stopped providing energy to Earth, most ecosystems would eventually vanish. Which of the following ecosystems would likely survive the longest after this hypothetical disaster?

A) pelagic ocean
B) tundra
C) deep benthic ocean
D) a desert spring

Question 19

Use the following figure to answer the question. In the figure, the jagged arrow leaving microorganisms and other detritivores represents which process?

A) organic compounds broken down by bacteria
B) energy consumed by bacteria
C) energy lost from a worm during cellular respiration
D) CO₂ and heat loss from detritus due to solar radiation and precipitation

Question 20

Which of the following are the main forms of chemical inputs and outputs that are recycled within an ecosystem?

A) soil elements, water, oxygen, carbon dioxide, chemicals within detritus (dead organisms)
B) sunlight and heat
C) inorganic and organic compounds
D) water, nitrogen, phosphorus, carbon, and heat

Question 21

Which of the following organisms is correctly paired with its trophic level?

A) cyanobacterium-primary consumer
B) grasshopper-secondary consumer
C) phytoplankton-primary producer
D) fungus-primary consumer

Question 22

Use the following figure to answer the question. Food web for a particular terrestrial ecosystem (arrows represent energy flow and numbers represent species)
Which species in the food web most likely represents both a primary and secondary consumer?

A) 2
B) 3
C) 4
D) 5

Question 23

If you applied a fungicide to a cornfield, what would you expect to happen to the rate of decomposition and net ecosystem production (NEP)?

A) Both decomposition rate and NEP would decrease.
B) Both decomposition rate and NEP would increase.
C) Decomposition rate would increase and NEP would decrease.
D) Decomposition rate would decrease and NEP would increase.

Question 24

Which of the following claims about marine ecosystem productivity is the most accurate?

A) production near the equator is highest because incoming solar radiation is the most intense
B) production near the equator is highest because reefs support a higher level of biodiversity
C) production in regions where there is higher micro- and macronutrient availability is highest
D) production in the Antarctic Ocean is one of the lowest due to the colder water temperatures

Question 25

Use the following figure to answer the question. Food web for a particular terrestrial ecosystem (arrows represent energy flow and numbers represent species)
Which species in the food web most likely represents a primary producer?

A) 1
B) 2
C) 3
D) 4

Question 26

Use the following figure to answer the question. Which terrestrial habitat type in the figure makes available the most net biomass tissue per unit area available for consumers?

A) tropical wet forest
B) open ocean
C) algal beds and reefs
D) wetlands

Question 27

Use the following figure to answer the question. Which of the following conclusions about productivity within the confines of the experimental ecosystem is most consistent with the data?

A) Productivity is higher at depth than at the surface, but only initially.
B) Productivity is higher at the surface than at depth; however, an additional experiment could further test the effect of depth by introducing FeSO4 at 30 m deep and measuring the chlorophyll a response.
C) Productivity is higher at the surface than at depth, and would be predicted to increase sharply after day 12.
D) Productivity at a depth of 30 m is low only because of a lack of sunlight, not a lack of iron sulfate.

Question 28

Use the following figure to answer the question. Which land-based ecosystem in the figure makes has the highest productivity per square meter?

A) tropical wet forest
B) Temperate evergreen forest
C) cultivated land
D) savanna

Question 29

Use the following figure to answer the question. Which habitat type in the figure covers the largest area?

A) tropical wet forest
B) rock, sand, ice
C) algal beds and reefs
D) open ocean

Question 30

Which of the following best explains why an ecosystem that exhibits very low net primary production [NPP, measured as J/(m2 x year)] could still represent one of the ecosystems that contributes the most to global net primary production?

A) Ecosystems with very low NPP may cover vast areas of the Earth's surface.
B) Ecosystems with very low NPP may have tight recycling of energy.
C) Low NPP ecosystems often store a lot of heat.
D) Higher NPP ecosystems are often located at latitudes where sunlight is less intense.

Question 31

Use the following figure to answer the question. Which ecosystem, if completely converted by humans to cultivated land, would have the largest negative impact on total NPP?

A) temperate evergreen forest
B) boreal forest
C) savanna
D) woodland and shrubland

Question 32

Use the following figure to answer the question. Diagram of a food web (arrows represent energy flow and letters represent species)
If the figure represents a marine food web, tertiary consumers are most likely ________.

A) C
B) D
C) E
D) H

Question 33

The amount of energy from light (or chemicals, in chemoautotrophic systems) converted to the chemical energy of organic molecules per unit time is defined as ________.

A) net primary production
B) gross primary production
C) primary production
D) total photosynthetic production

Question 34

Many of the organisms in the ocean are nutrient-limited. Which of the following would be the most reasonable approach if you wanted to investigate this phenomenon?

A) observe Antarctic Ocean productivity from year to year to see if it changes
B) experimentally enrich some areas of the ocean and compare their productivity to that of untreated areas
C) compare nutrient concentrations between the photic zone and the benthic zone in various marine locations
D) contrast nutrient uptake by autotrophs in marine locations that are different temperatures

Question 35

Given the following data set, reducing the availability of which nutrient would best help aquatic biologists and managers reduce a eutrophication problem in a lake?

A) nitrogen
B) phosphorus
C) iron
D) calcium

Question 36

During a year, plants never use 100% of the incoming solar radiation for photosynthesis. Which of the following is the most reasonable explanation for this?

A) Plants cannot photosynthesize as well in warm temperatures as in cold temperatures.
B) Plants do not intercept all incoming light, as some light will strike water, bare soil, or rock.
C) The pigments that drive photosynthesis absorb all of the wavelengths of light; however, some of the light is subsequently reflected off the plant.
D) At least 75% of all incoming light is reflected, absorbed, or scattered back by clouds in the atmosphere.

Question 37

Which of the following is an accurate statement regarding mineral nutrients in soils and their implication for primary productivity?

A) Globally, phosphorous availability is most limiting to primary productivity.
B) Adding a nonlimiting nutrient will stimulate primary productivity.
C) Phosphorous is sometimes unavailable to producers due to leaching.
D) Alkaline soils are more productive than acidic soils.

Question 38

Which of the following best explains why terrestrial productivity is higher in equatorial climates than in temperate climates?

A) Productivity increases with solar intensity.
B) Productivity increases with temperature and water availability.
C) Productivity increases with proximity to the sun.
D) Productivity increases with day length.

Question 39

Use the following figure to answer the question. After looking at the evidence from the experiment in the figure, which of the following is the most accurate conclusion about productivity in marine ecosystems?

A) Nothing can be said based on this information.
B) Marine organisms break down iron for energy and thus for productivity.
C) Iron availability limits productivity.
D) Productivity increases when chlorophyll a is added.

Question 40

Which of the following has the greatest effect on the rate of chemical cycling within an ecosystem?

A) the ecosystem's rate of primary production
B) the secondary production efficiency of the ecosystem's consumers
C) the rate of decomposition in the ecosystem
D) the trophic efficiency of the ecosystem

Question 41

Use the figure to answer the question: Which arrow, if representing magnitude, should show the largest biomass exiting primary producers?

A) arrow leading to primary consumers
B) arrow leading to detritus
C) arrow leading back to primary producers
D) loss of heat arrow

Question 42

The flow of energy in an example arctic ecosystem goes through a simple food chain as depicted below:
Phytoplankton → zooplankton → fish → seals → polar bears
Which of the following is the most accurate conclusion when considering the energetics in this food chain?

A) Polar bears could provide more biomass of food for humans than seals can.
B) The total biomass of the fish is lower than that of the seals.
C) Seal populations are larger than fish populations.
D) Fish can potentially provide more food for humans than seal meat.

Question 43

Consider the food chain of grass → grasshopper → mouse → snake → hawk. About how much of the chemical energy fixed by photosynthesis of the grass (100 percent) is available to the hawk, assuming a 10% trophic efficiency?

A) 0.01%
B) 0.1%
C) 1%
D) 10%

Question 44

Which of the following is a reason that inefficient transfer of energy among trophic levels results in the typically high endangerment status of many top-level predators?

A) Top-level predators often have small populations that are sparsely distributed.
B) Predators have relatively large population sizes.
C) Predators are more disease-prone than animals at lower trophic levels.
D) Top-level predators are more likely to be stricken with parasites.

Question 45

Use the following figure to answer the question. Diagram of a food web (arrows represent energy flow and letters represent species)
If the figure represents a terrestrial food web, the combined biomass of C + D would probably be ________.

A) greater than the biomass of A
B) greater than the biomass of B
C) less than the biomass of A + B
D) less than the biomass of E

Question 46

What advantage would there be for an ecosystem ecologist to measure net ecosystem production (NEP) instead of net primary production (NPP)?

A) NPP cannot be expressed in energy/unit of area/unit of time.
B) NEP can be expressed in terms of carbon fixed by photosynthesis for an entire ecosystem, minus respiration by producers, allowing the measurement of net CO₂ flux.
C) NEP represents the amount of energy from light converted to chemical energy, minus the energy used by all organisms for cellular respiration, which could indicate whether or not carbon is being stored.
D) NPP shows the rate at which the standing crop is utilized by consumers.

Question 47

Which statement best describes what ultimately happens to the chemical energy that is consumed but not used to produce new biomass in the process of energy transfer between trophic levels in an ecosystem?

A) It is undigested and winds up in the feces and is not passed on to higher trophic levels.
B) It is used by organisms to maintain their life processes through the reactions of cellular respiration.
C) Heat produced by cellular respiration is used by heterotrophs for thermoregulation.
D) It is eliminated as feces or is dissipated into space as heat as a result of cellular respiration consistent with the second law of thermodynamics.

Question 48

Which of the following is primarily responsible for limiting the number of trophic levels in most ecosystems?

A) Many primary and higher-order consumers are opportunistic feeders.
B) Decomposers compete with higher-order consumers for nutrients and energy.
C) Nutrient cycling rates tend to be limited by decomposition.
D) Energy transfer between trophic levels is usually less than 20 percent efficient.

Question 49

Which of the following is a reason that a diet consisting primarily of fruits and vegetables results in a smaller ecological footprint than a diet high in meat content?

A) Fewer animals are raised for human consumption.
B) There is an excess of plant biomass in all terrestrial ecosystems.
C) Vegetarians require less chemical energy than others
D) Eating meat is an inefficient way of acquiring photosynthetic productivity.

Question 50

Why is it that satellites, using wavelength reflectance technology, detect variable levels of productivity across latitudes in the Earth's oceans, rather than an increase approaching the equator?

A) Temperatures at the equator often exceed those which are optimal for primary production.
B) Light at the equator is too constant and direct.
C) NPP in Earth's open oceans could differ due to variability in depth, nutrients, the presence of coral reefs, or by ocean currents.
D) Satellites detect differences by measuring the amount of water vapor emitted by transpiring producers, and this is a variable measurement in the oceans.

Question 51

Acid precipitation lowered the pH of soil in a terrestrial ecosystem that supported a diverse community of plants and animals. The decrease in pH eliminated all nitrogen-fixing bacteria populations in the area. Which prediction most accurately reflects the impact this will have on the community?

A) Since phosphorus can replace nitrogen as an essential nutrient, the impact will be minimal.
B) Plants can obtain the nitrogen necessary for growth from the atmosphere, but bacterial communities will be negatively impacted.
C) Primary producers will suffer from nitrogen deficiency and the entire community will experience a decrease in carrying capacity.
D) The decrease in pH actually increases the availability of soil nutrients, so other nutrients that were less available cause an increase in primary production and an increase in biomass at other trophic levels.

Question 52

Owls eat rats, mice, shrews, and small birds. Assume that, over a period of time, an owl consumes 5,000 J of animal material. The owl loses 2,300 J in feces and owl pellets and uses 2,500 J for cellular respiration. Which of the following best estimates the production efficiency of this owl?

A) 8%
B) 7.4%
C) 2%
D) 40%

Question 53

Which one of the following correctly ranks these organisms in order from lowest to highest percent in production efficiency?

A) mammals, fish, insects
B) insects, fish, mammals
C) fish, insects, mammals
D) mammals, insects, fish

Question 54

Which of the following ecosystems would likely have the largest net primary productivity per hectare and why?

A) open ocean, because of the total biomass of photosynthetic autotrophs
B) grassland, because of rapid growth, the small standing crop biomass that results from consumption by herbivores, and rapid decomposition
C) tundra, because of the incredibly rapid period of growth during the summer season
D) deep ocean, due to the high activity of chemoautotrophs at deep sea vents

Question 55

Use the following figure to answer the question. Which of the following claims is most consistent with the figure regarding productivity in this ecosystem?

A) Primary consumers consume less biomass than secondary consumers.
B) Between 80% and 90% of the energy is lost between most trophic levels.
C) Between 10% and 20% of the energy is lost between most trophic levels.
D) Productivity increases with each trophic level.

Question 56

How is net ecosystem production (NEP) typically estimated in ecosystems?

A) by detecting the amount of heat energy released by the ecosystem
B) by measuring gas exchange from vegetation as well as estimates of respiration by all other organisms
C) by measuring the rate of decomposition by detritivores
D) by calculating the annual total of incoming solar radiation per unit of area

Question 57

For most terrestrial ecosystems, pyramids composed of species abundances, biomass, and energy are similar in that they have a broad base and a narrow top. The primary reason for this pattern is that ________.

A) secondary consumers and top carnivores require less energy than producers
B) at each step, energy is lost from the system
C) biomagnification of toxic materials limits the secondary consumers and top carnivores
D) top carnivores and secondary consumers have a more general diet than primary producers

Question 58

A porcupine eats 3,000 J of plant material. Of this, 2,100 J is indigestible and is eliminated as feces, 800 J are used in cellular respiration, and 100 J are used for growth and reproduction. What is the approximate production efficiency of this animal?

A) 0.03%
B) 3%
C) 11%
D) 33%

Question 59

Which of the following best explains the observation that matter may be gained by, or lost from, ecosystems?

A) Chemoautotrophic organisms can convert matter to energy.
B) Matter can move from one ecosystem to another.
C) Photosynthetic organisms convert solar energy to sugars.
D) Heterotrophs convert heat to energy.

Question 60

Use the following figure to answer the question. Based on the figure, which of the following is the most complete explanation for the results?

A) nutrient levels in the control watershed are being lost due to evapotranspiration from leaves
B) nutrient levels remaining in the control plots are lower
C) nutrient levels remaining in the devegetated watershed are lower
D) nutrients dissolved in water are lost from the control area more than the devegetated area

Question 61

Use the following figure to answer the question. Based on the information provided, which of the following represents the human impact on the global nitrogen cycle?

A) industrial nitrogen fixation
B) nitrogen lost to the atmosphere
C) reduction of nitrogen available to terrestrial ecosystems
D) reduction of nitrogen fixation by bacteria

Question 62

Use the following figure to answer the question. Based on information provided, which of the following represents the greatest flux of water from one reserve to another?

A) precipitation to the ocean
B) the ocean to the atmosphere
C) runoff in streams and the water table to the ocean
D) evaporation and transpiration of terrestrial vegetation to the atmosphere

Question 63

Which of the following is an example of biological augmentation?

A) adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability
B) using a bulldozer to regrade a strip mine
C) dredging a river bottom to remove contaminated sediments
D) adding fertilizer to soil poor in nutrients to increase plant growth

Question 64

Which of the following has the greatest effect on the rate of chemical cycling in an ecosystem?

A) the rate of decomposition in the ecosystem
B) the production efficiency of the ecosystem's consumers
C) the trophic efficiency of the ecosystem
D) the location of the nutrient reservoirs in the ecosystem

Question 65

Use the following figure to answer the question. Based on the information provided, which of the following contains the largest source or pool of nitrogen?

A) industrial nitrogen fixation
B) nitrogen lost to the atmosphere
C) internal nitrogen cycling in the oceans
D) nitrogen fixation by bacteria

Question 66

If a pristine river valley was converted to a gravel mine, altering the stream channel and also impacting the associated aquatic and terrestrial biota, which of the following would most likely be the first step to restoring the former river valley ecosystem?

A) restore the physical structure of the river
B) restore native species that have been extirpated due to mining disturbance
C) remove competitive invasive species
D) remove toxic pollutants

Question 67

The discipline that applies ecological principles to returning degraded ecosystems to a more natural state is known as ________.

A) landscape ecology
B) conservation ecology
C) restoration ecology
D) resource conservation

Question 68

If you applied a fungicide to a cornfield, what would you expect to happen to the rate of decomposition and net ecosystem production (NEP)?

A) both decomposition rate and NEP would decrease
B) neither would change
C) decomposition rate would increase and NEP would decrease
D) decomposition rate would decrease and NEP would increase

Question 69

The discipline that applies ecological principles to returning degraded ecosystems to a more natural state is known as ________.

A) restoration ecology
B) thermodynamics
C) eutrophication
D) biogeochemistry

Question 70

Which of the following is an example of bioremediation?

A) adding nitrogen-fixing microorganisms to a degraded ecosystem to increase nitrogen availability
B) using a bulldozer to regrade a strip mine
C) reconfiguring the channel of a river
D) adding seeds of a chromium-accumulating plant to soil contaminated by chromium

Question 71

Which of the following statements is correct about biogeochemical cycling?

A) Phosphorus is the limiting nutrient that most widely affects biomass production.
B) The phosphorus cycle involves the weathering of rocks.
C) The carbon cycle has maintained a constant atmospheric concentration of carbon dioxide for the past million years.
D) The nitrogen cycle involves movement of diatomic nitrogen between the biotic and abiotic components of the ecosystem.

Question 72

Which of the following best represents the goal of restoration ecology?

A) replacing a ruined ecosystem with a more suitable ecosystem for that area
B) returning degraded ecosystems to a more natural state
C) managing competition among species in human-altered ecosystems
D) preventing further degradation by protecting an area with park status

Question 73

Nitrifying bacteria participate in the nitrogen cycle mainly by ________.

A) converting nitrogen gas to ammonia
B) releasing ammonium from organic compounds, thus returning it to the soil
C) converting ammonium to nitrate, which plants absorb
D) incorporating nitrogen into amino acids and organic compounds

Question 74

Which of the following best describes the role of nitrifying bacteria in the nitrogen cycle?

A) converting nitrogen gas to ammonia
B) releasing ammonium from organic compounds, thus returning it to the soil
C) converting ammonium to nitrate, which plants absorb
D) incorporating nitrogen into amino acids and organic compounds

Question 75

Which of the following organisms is correctly paired with a trophic level?

A) cyanobacterium-secondary consumer
B) grasshopper-primary consumer
C) zooplankton-primary producer
D) grass-decomposer

Question 76

Which of the following was a conclusion of the Hubbard Brook watershed deforestation experiment?

A) deforestation decreased water runoff
B) nitrate concentration in waters draining from the deforested area were lowest
C) calcium levels remained high in the soil of deforested areas
D) nitrate concentration in waters draining from the deforested area became dangerously high

Question 77

Which of these ecosystems has the lowest net primary production per square meter?

A) a salt marsh
B) an open ocean
C) a coral reef
D) a tropical rain forest

Question 78

As part of the carbon cycle, which of the following reservoirs of carbon is the largest?

A) the ocean
B) the atmosphere
C) fossilized plant and animal remains (coal, oil, and natural gas)
D) sediments and sedimentary rocks

Question 79

Which of the following is a reason that logged tropical rain forest soils typically have nutrient-poor soils?

A) Tropical bedrock contains little phosphorous.
B) Logging results in soil temperatures that are lethal to nitrogen-fixing bacteria.
C) Most of the nutrients in the ecosystem are removed in the harvested timber.
D) The cation exchange capacity of the soil is reversed as a result of logging.

Question 80

Which of the following was a result of the Hubbard Brook watershed deforestation experiment?

A) Most minerals were not recycled within the intact forest ecosystem.
B) Calcium levels remained high in the soil of deforested areas.
C) Deforestation decreased water runoff.
D) The nitrate concentration in waters draining the deforested area became dangerously high.