Biology for AP Courses

Julianne Zedalis, John Eggebrecht

Chapter 37

Ecosystems - all with Video Answers

Educators

Chapter Questions

Problem 1

What type of ecosystem is the rarest on Earth, among both terrestrial and aquatic exosystems?
a. ocean
b. freshwater
c. grasslands
d. tundra

April Townson

April Townson

Numerade Educator

Problem 2

If an ecosystem is considered to be highly resilient, what can be inferred about that ecosystem?
a. The ecosystem is in a steady state.
b. The ecosystem has the ability to remain in equilibrium despite disturbance.
c. The ecosystem recovers quickly from disturbance.
d. The ecosystem is exposed to disturbances.

Chaim Chernoff

Numerade Educator

Problem 3

What is a re-created ecosystem in a laboratory environment known as?
a. mesocosm
b. simulation
c. microcosm
d. duplication

April Townson

Numerade Educator

Problem 4

A scientist wants to analyze how deer grazing alters plant species composition in a forest and sections off a portion of the forest for observation and analysis. What type of system is the scientist using?
a. mesocosm
b. simulation
c. microcosm
d. duplication

Chaim Chernoff

Numerade Educator

Problem 5

What term describes the use of mathematical equations in the modeling of linear aspects of ecosystems?
a. analytical modeling
b. simulation modeling
c. conceptual modeling
d. microcosm modeling

April Townson

Numerade Educator

Problem 6

If a scientist constructs a flow chart to depict the interactions among species in an estuary, what kind of
model is she creating?
a. analytical model
b. stimulation model
c. conceptual model
d. microcosm model

Chaim Chernoff

Numerade Educator

Problem 7

What are usually the primary producers in an ocean grazing food web?
a. plants
b. animals
c. fungi
d. phytoplankton

April Townson

Numerade Educator

Problem 8

Which of the following statements is true of trophic levels in an ecosystem?
a. Food chains are accurate representations of dynamics in an ecosystem.
b. In terrestrial ecosystems, primary producers commonly eat plants.
c. Food webs are easier to interpret than food chains.
d. The least amount of energy is available at the top of a food chain.

Chaim Chernoff

Numerade Educator

Problem 9

Where are coral reefs found?
a. shallow ocean water
b. deep ocean water
c. deep ocean surfaces
d. shallow freshwater

April Townson

Numerade Educator

Problem 10

What is the weight of living organisms in an ecosystem at a particular point in time known as?
a. energy
b. productivity
c. entropy
d. biomass

Chaim Chernoff

Numerade Educator

Problem 11

If you wanted to measure gross primary productivity in a terrestrial ecosystem, what would you measure?
a. rate of energy incorporation by plants
b. energy available after a plant incorporates energy for its own biological functions
c. amount of energy from plants entering the trophic level of deer
d. total mass of plants and animals in an area at a given point in time

April Townson

Numerade Educator

Problem 12

What law of chemistry determines how much energy can be transferred when it is converted from one form to another?
a. the first law of thermodynamics
b. the second law of thermodynamics
c. the conservation of matter
d. the conservation of energy

Chaim Chernoff

Numerade Educator

Problem 13

What is the primary factor that limits the length of food chains in ecosystems?
a. low energy transfer efficiency between trophic levels
b. too much net primary productivity
c. excess assimilation
d. low gross primary productivity

April Townson

Numerade Educator

Problem 14

What type of pyramid is considered the most representative of ecosystem structure?
a. biomass
b. energy
c. number of organisms
d. number of species

Chaim Chernoff

Numerade Educator

Problem 15

Why are the numbers of primary producers smaller than the number of primary consumers in the English
Channel ecosystem?
a. The primary consumers have a high tumover rate.
b. The primary producers have a low turnover rate.
c. The apex consumers have a low turnover rate.
d. The primary producers have a high turnover rate.

April Townson

Numerade Educator

Problem 16

What forms of life are found in areas where sunlight is unavailable and use inorganic molecules as an energy source?
a. photoautotrophs
b. chemoautotrophs
c. primary consumers
d. secondary consumers

Chaim Chernoff

Numerade Educator

Problem 17

What is the process whereby nitrogen is brought into organic molecules called?
a. nitrification
b. denitrification
c. nitrogen fixation
d. nitrogen cycling

April Townson

Numerade Educator

Problem 18

Which of the following is a mechanism by which phosphorus is released into the environment?
a. rock weathering
b. decomposition of organic molecules
c. volcanic activity
d. geothermal vent activity

Chaim Chernoff

Numerade Educator

Problem 19

What is produced by eutrophication via excess nitrogen where a hydrologic reservoir lacks normal flora
and fauna?
a. fixation
b. acid rain
c. dead zones
d. nitrification

April Townson

Numerade Educator

Problem 20

What is a potential consequence of excess phosphorus and nitrogen in an ecosystem?
a. This could result in increased global temperatures.
b. Subduction can be promoted.
c. These elements might be fixed in excess.
d. A dead zone could be produced from depleted oxygen.

Chaim Chernoff

Numerade Educator

Problem 21

What term is given for freshwater that flows from rain or melting ice in the hydrologic cycle?
a. residence time
b. surface runoff
c. evaporation
d. sublimation

April Townson

Numerade Educator

Problem 22

What most strongly influences how much carbon is present in a given location?
a. number of bacteria
b. nunoff
c. eutrophication
d. atmosphere and water exchange

Chaim Chernoff

Numerade Educator

Problem 23

Why does grouping terrestrial organisms into biomes obscure diversity?
a. Biomes groups terrestrial organisms only on the basis of similar habitat conditions.
b. Organisms belonging to a similar biome have dissimilarities in their makeup.
c. There is variation within different types of biomes that biome categorization does not capture.
d. Terrestrial biomes are defined based only on the growth form of the dominant vegetation.

April Townson

Numerade Educator

Problem 24

Why are mesocosm and microcosm experiments not considered to represent the true nature of ecosystems?
a. The ecosystem is either recreated or partitioned in both the experiments, which may alter the dynamics of the ecosystem the experiments are aiming to analyze.
b. In both the experiments, dynamics of the ecosystem may get altered due to differences in species numbers and diversity although there are no alterations in the environment.
c. In both the experiments, the ecosystem is recreated which may alter the dynamics of the ecosystem the experiments are aiming to analyze.
d. Altering a natural ecosystem through partitioning, which occurs in both the experiments may change its dynamics due to differences in species numbers and diversity.

Chaim Chernoff

Numerade Educator

Problem 25

If a scientist wanted to monitor a desert food chain, what type of model might they develop and why?
a. An analytical model would be ideal because they can address simple, linear ecosystem components that are mathematically complex.
b. A simulation model would be ideal because they can address simple, linear systems that are mathematically complex.
c. An analytical model would be ideal as they are considered ecologically more realistic than any other model.
d. A simulation model would be ideal because it uses numerical techniques to solve problems and
visualize the complex relationships that exist in the ecosystem.

April Townson

Numerade Educator

Problem 26

Compare and contrast food chains and food webs. What are the strengths of each concept in describing ecosystems?
a. Both food chain and food web follow a single path as energy is transferred in an ecosystem. Food chains are easier to follow and experiment with but less accurate whereas food webs are more holistic and complex.
b. Both food web and food chain describe energy transfer dynamics in an ecosystem. Food chains are non-linear systems which are easier to follow and experiment with whereas food webs are linear, holistic and can be directly used as input for simulation models.
c. Both food chain and food web follow a single path as energy is transferred in an ecosystem. Food chains are linear systems, easier to follow and used directly as input for simulation models, whereas food webs are non-linear, accurate, holistic and flexible for analytical modeling.
d. Both food web and food chain describe energy transfer dynamics in an ecosystem. Food chains
are linear systems, easier to follow and experiment with whereas food webs are non-linear, accurate and holistic and can be directly used as input for simulation models.

Chaim Chernoff

Numerade Educator

Problem 27

Name one natural and one human-related type of disturbance. Why are they of concern to conservationists?
a. Lightening is a type of natural disturbance whereas pollution is a human related disturbance. Both are of concern to conservationists because they affect the entire ecosystem.
b. Fire is a type of natural disturbances whereas agriculture is a human related disturbance. Both
types are of concern to conservationists because ecosystems cannot bounce back from a disturbance.
c. Pollution is a type of natural disturbance whereas lightening is a human related disturbance. Both are of concern to conservationists because they alter ecosystems.
d. Lightening is a type of natural disturbance whereas pollution is a human related disturbance. Both are of concern to conservationists because they alter ecosystems.

April Townson

Numerade Educator

Problem 28

Compare grazing and detrital food webs. Why would they both be present in the same ecosystem?
a. The primary producers of detrital food webs are decomposers whereas those of grazing food
webs are non-photosynthetic. Both primary producers support different components of the
ecosystem.
b. The primary producers of detrital food webs are photosynthetic whereas those of grazing food
webs are decomposers. Both primary producers support different components of the ecosystem.
c. The primary producers of detrital food webs are decomposers whereas those of grazing food
webs are photosynthetic. Both primary producers support different components of the
ecosystem.
d. The primary producers of detrital food webs are chemoautotrophs whereas those of grazing food
webs are photosynthetic. Both primary producers support different components of the ecosystem.

Chaim Chernoff

Numerade Educator

Problem 29

How does the amount of food that endotherms and ectotherms consume compare with their net production efficiency (NPE)?
a. The amount of food eaten by an animal does not affect its net production efficiency (NPE).
b. Endotherms use more energy compared to ectotherms due to energy loss by respiration and heat.
c. Both endotherms and ectotherms use the same energy from food.
d. Ectotherms use more energy compared to endotherms due to energy loss by respiration and heat.

April Townson

Numerade Educator

Problem 30

Compare the three types of ecosystem pyramids and how well they describe ecosystem structure. Identify which ones can be inverted and give a specific example of an inverted pyramid for each.
a. The three types of ecosystem pyramids are pyramids of energy, number and biomass out of
which number and energy pyramids can be inverted. Examples of inverted pyramids of
number and energy are temperate forests in summer and phytoplankton in the English
Channel respectively.
b. The three types of ecosystem pyramids are pyramids of energy, number and biomass out of
which number and biomass pyramids can be inverted. Examples of inverted pyramids of
number and biomass are temperate forests in summer and phytoplankton in the English
Channel respectively.
c. The three types of ecosystem pyramids are pyramids of energy, number and biomass out of
which number and biomass pyramids can be inverted. Examples of inverted pyramids of
number and biomass are temperate forests in summer and Silver Springs ecosystem in Florida
respectively.
d. The three types of ecosystem pyramids are pyramids of energy, number and biomass out of
which number and biomass pyramids can be inverted. Examples of inverted pyramids of
number and biomass are grasslands in summer and phytoplankton in the English Channel
respectively.

Chaim Chernoff

Numerade Educator

Problem 31

Why do scientists more commonly analyze net primary productivity compared with gross primary productivity?
a. Net primary productivity incorporates features like production at present and next trophic levels, whereas gross primary productivity does not.
b. Net primary productivity is the rate at which photosynthetic primary producers incorporate energy from the sun.
c. As net primary productivity is the energy content available to the organisms of the next trophic level.
d. As respiration and heat loss uses energy of the primary producer, therefore, net primary productivity is what is actually available to primary consumers.

April Townson

Numerade Educator

Problem 32

Describe nitrogen fixation and why it is important to agriculture.
a. The process of nitrate formation from ammonia is called nitrogen fixation. It improves
agricultural production as nitrogen is required by plants for nucleotide and protein formation.
b. The process of nitrogen being bonded to organic molecule is called nitrogen fixation. It improves
the crop yield by allowing the plants to compete with weeds.
c. The reduction of nitrates back to nitrogen gas is called nitrogen fixation. It improves agricultural
production as nitrogen is required by plants for nucleotide and protein formation.
d. The process of nitrogen being bonded into organic molecules is called nitrogen fixation. It
improves agricultural production as nitrogen is required by plants for nucleotide and protein
formation.

Chaim Chernoff

Numerade Educator

Problem 33

How do agricultural animals such as cattle raise atmospheric carbon levels? What is a side effect?
a. Cattle produce carbon monoxide, which when inhaled can cause death.
b. Cattle produce carbon monoxide, which is a major contributor to global warming.
c. Agricultural animals increase the amount of greenhouse gases by producing carbon dioxide and methane, so they contribute to global warming.
d. Agricultural animals increase the amount of greenhouse gases by producing ozone, which contributes to global warming.

April Townson

Numerade Educator

Problem 34

What form of sulfur is found in the atmosphere and how does it leave the atmosphere?
a. hydrogen sulfide, which leaves the atmosphere as weak sulfur dioxide rain
b. sulfur dioxide, which leaves the atmosphere as weak sulfur dioxide rain
c. hydrogen sulfide, which leaves the atmosphere as weak sulfuric acid rain
d. sulfur dioxide, which leaves the atmosphere as weak sulfuric acid rain

Chaim Chernoff

Numerade Educator

Problem 35

Producers and consumers are necessary for ecosystem function and for energy to pass through an ecosystem. What might happen in an aquatic system with excess producers relative to consumers?
a. Oxygen depletion would result in dieoff.
b. There would be no basal energy source.
c. Carbon cannot be sequestered.
d. There would be more undigestable animal parts.

April Townson

Numerade Educator

Problem 36

Energy is a fundamental component in an ecosystem and is contributed by the primary producers. Describe how light energy can, in turn, support the consumers of an ecosystem.
a. Light energy is converted by primary producers and primary consumers. Consumers belonging to
higher trophic levels feed on them to gain energy.
b. Primary producers can only obtain energy from sunlight by photosynthesis and gain energy by
feeding on them or other consumers which have consumed these producers.
c. Primary producers convert light energy by photosynthesis and consumers gain energy by
feeding on them or other consumers which have consumed these producers.
d. Primary producers convert light energy through chemosynthesis and consumers gain energy by
feeding on them or other consumers which have consumed these producers.

Chaim Chernoff

Numerade Educator

Problem 37

In a microcosm experiment using fish tanks to mimic a lake environment, an increase in the number of stickleback species would increase the dissolved organic carbon particle size. How could this affect primary producers in the ecosystem?
a. enhance growth rate
b. increase abundance
c. decrease abundance
d. maintain growth rate

April Townson

Numerade Educator

Problem 38

Studies on stickleback fish revealed that the presence of two species of stickleback reduced the amount of algal blooms relative to the presence of one species of stickleback in a microcosm experiment. How does this occur?
a. This occurred as the presence of two species caused an increase in dissolved organic carbon
molecule size, which blocked the penetration of light in water and prevented algal
photosynthesis.
b. This occurred because two stickleback species consumed all the nutrients which prevented
algae from being able to grow.
c. This occurred because dissolved organic carbon molecule size increased in the presence of one
fish species which increased the amount of algal blooms.
d. This occurred as algae are consumed in more amounts in the presence of two stickleback species.

Chaim Chernoff

Numerade Educator

Problem 39

This figure depicts energy exchange through trophic levels. Which level represents the primary producers?
a. A
b. B
c. C
d. D

April Townson

Numerade Educator

Problem 40

How much carbon $\left(\mathrm{g} / \mathrm{m}^{2}\right)$ is released into the atmosphere as a result of the metabolic activity of herbivores? Give your answer to the nearest whole number.
a. 125 $\mathrm{g} / \mathrm{m}^{2}$ carbon is released into the atmosphere as a result of the metabolic activity of herbivores.
b. 65 $\mathrm{g} / \mathrm{m}^{2}$ carbon is released into the atmosphere as a result of the metabolic activity of herbivores.
c. 60 $\mathrm{g} / \mathrm{m}^{2}$ carbon is released into the atmosphere as a result of the metabolic activity of herbivores.
d. 5 $\mathrm{g} / \mathrm{m}^{2}$ carbon is released into the atmosphere as a result of the metabolic activity of herbivores.

Anand Jangid

Numerade Educator

Problem 41

The following is a food web for a meadow habitat that occupies 25.6 $\mathrm{km}^{2} .$ The primary producers' biomass is uniformly distributed throughout the habitat and totals $1,500 \mathrm{kg} / \mathrm{km}^{2} .$ Developers have approved a project that will permanently reduce the primary producers' biomass by 50 percent and remove all rabbits and deer. Which of the following is the most likely result at the completion of the project?
a. The biomass of coyotes will be 6 kg, and the biomass of hawks will be 0.5 kg.
b. The biomass of coyotes will be dramatically reduced.
c. The coyotes will switch prey preferences and outcompete the hawks.
d. There will be 50 percent fewer voles and 90 percent fewer hawks.

Caroline Jones

Numerade Educator

Problem 42

This figure shows a food web of an ecosystem. What would happen to the food web if all of the species of the entire row B was wiped out by a natural disaster such as an
oil spill? Why?
a. The producers may die out, causing the food web to collapse.
b. The food web would not be affected as the secondary and tertiary consumers would become
primary and secondary consumers, respectively.
c. The tertiary consumers would die out due to lack of food and this could potentially lead to
collapse of the entire food web.
d. The food web might suffer from loss of primary producers for a while which would then recover
quickly, thus, reviving the ecosystem.

Chaim Chernoff

Numerade Educator

Problem 43

Humans are very active in modifying ecosystems worldwide. If a new set of buildings on the edge of a forest block sunlight from reaching the majority of one part of the forest, what might happen to that part of the forest?
a. Herbivores would occur in high abundance.
b. Plants would occur in high abundance.
c. Everything would remain the same.
d. Herbivores would occur in low abundance.

April Townson

Numerade Educator

Problem 44

If you examined predator-prey relationships within an ecosystem and noticed that the removal of predators also resulted in the die-off of herbivores, what would you
suspect occurred?
a. Removal of predators would directly lower the number of herbivores.
b. The lack of predators could mean that too much primary production occurred.
c. Herbivores from another region may have entered the ecosystem and consumed the
primary producers, causing death of the original herbivores species.
d. Overeating by herbivores could have caused depletion of the primary producers, leaving the
herbivores without enough food.

Chaim Chernoff

Numerade Educator

Problem 45

Although producers are essential for energy to flow into an ecosystem, consumers also have important roles. What might happen in an aquatic system with excess consumers relative to producers?
a. Oxygen depletion would result in dieoff.
b. There would be an excess of the basal energy source.
c. Consumers would deplete the abundance of producers.
d. There would be more undigestable animal parts.

April Townson

Numerade Educator

Problem 46

The following is the equation for trophic level transfer efficiency: (production at present trophic level/production at past trophic level)\times100. If primary producers produce $1600 \mathrm{kcal} / \mathrm{m}^{2},$ and primary consumers have 900 $\mathrm{kcal} / \mathrm{m}^{2}$ what is the trophic level transfer efficiency?
a. 50
b. 200
c. 800
d. 1600

Chaim Chernoff

Numerade Educator

Problem 47

There are four trophic levels in a food chain and the amount of energy at the trophic level of the primary
producer is $33,000 \mathrm{kcal} / \mathrm{m}^{2} .$ Which of the following represents the amount of energy of the tertiary consumer?
$\begin{array}{ll}{\text { a. }} & {75 \mathrm{kcal} / \mathrm{m}^{2}} \\ {\text { b. }} & {500 \mathrm{kcal} / \mathrm{m}^{2}} \\ {\text { c. }} & {11,000 \mathrm{kcal} / \mathrm{m}^{2}} \\ {\text { d. }} & {33,000 \mathrm{kcal} / \mathrm{m}^{2}}\end{array}$

April Townson

Numerade Educator

Problem 48

Why does this figure show a higher value of gross productivity for the decomposers than the tertiary
consumers?
a. Due to the difference in conversion efficiencies of decomposers and tertiary consumers.
b. Because large animals are tertiary consumers whereas small microorganisms are decomposers.
c. Because tertiary consumers only consume secondary consumers whereas decomposers consume dead components of each trophic level.
d. Because tertiary consumers only consume primary consumers whereas decomposers consume dead components of each trophic level.

Chaim Chernoff

Numerade Educator

Problem 49

One of the key concerns about global climate change is excess amounts of carbon being released into the atmosphere. There are, however, some ways in which carbon can be sequestered from the atmosphere. Which of the following is a natural process that promotes carbon sequestration?
a. burning fossil fuels
b. methane from cattle
c. photosynthesis by plants
d. volcanic eruption

April Townson

Numerade Educator

Problem 50

The food web shown below utilizes an arrow pointing from a species feeds on another to indicate the trophic structure of a simplified estuarine ecosystem at the boundary between the ocean and the shore.
A. Analyze the interactions among species and indicate primary producers by circling the node in the food web. Identify the primary producers by circling the nodes in the food web.
B. Predict quantitatively how free energy availability for a top species such as the one designated as T in the web changes if it feeds directly on S, assuming the abundance of species S is limited only by radiant energy input.
C. Consider the consequences of the dietary shift described in B if the abundance of species becomes depleted due to consumption by species T. Under those circumstances refine your analysis of the food web to describe the potential effect on species Q and R.
D. Based on the preceding analyses, construct a claim regarding the effect of the structure, in terms of biodiversity and number of interactions among species, on ecosystem stability.

Chaim Chernoff

Numerade Educator