Question 1

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?

Accepted Answer

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. C

Question 2

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?

Accepted Answer

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. D

Question 3

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?

Accepted Answer

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. A

Question 4

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?

Accepted Answer

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 5

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?

Accepted Answer

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 6

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

Accepted Answer

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

Question 7

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

Accepted Answer

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

Question 8

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?

Accepted Answer

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

Question 9

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?

Accepted Answer

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

Question 10

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

Accepted Answer

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.

Question 11

Which of the following terms encompasses all of the others?

Accepted Answer

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

Question 12

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

Accepted Answer

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 13

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?

Accepted Answer

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 14

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 ________.

Accepted Answer

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

Question 15

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?

Accepted Answer

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 16

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

Accepted Answer

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

Question 17

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

Accepted Answer

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

Question 18

Which of the following best represents the actions of photoautotrophs?

Accepted Answer

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

Question 19

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

Accepted Answer

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

Question 20

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?

Accepted Answer

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

Exam 55: Energy Flow and Chemical Cycling in Ecosystems

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?

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?