BIO 200 Exam 2 Part 1 Questions with
Complete Answers
Give examples of symbiotic and non-symbiotic mutualism. Describe at least one way
in which a mutualism affects your daily life. - ANSWER-Non-symbiotic: a cleaner fish
and the organisms they come across to "clean"
Symbiotic: bacteria living in our guts which aid in digestion (also an example of one
way mutualism affects my daily life)
Compare and contrast trophic levels, food chains, and food webs. How are these
concepts related, and how do they differ? - ANSWER-Trophic levels are the ranks of
food hierarchies. Food chains are a simple way to map the cyclical transition of
feeding from plant to herbivore to predator to bigger predator to detritivores to
decomposition and then back to plant again.
A food web is more complex than a food chain because it is not linear, more
complex, and more realistic.
The trophic levels help to classify the members of the food chains and webs into
community hierarchies. They show us how much food and energy are available to
each trophic level and then how much will be passed on (10% rule).
What is meant by the term keystone species, and what types of organisms are most
often considered keystone species? - ANSWER-Keystone species are those which
contribute so much to their environment that if removed from a community will result
in the destruction of said community. Secondary and tertiary consumers on the
trophic cascade are typically considered to be keystone.
Describe the process of primary succession. How does it differ from secondary
succession? Give an example of each. - ANSWER-Primary succession is when a
community has undergone an event so catastrophic that none of its plants or soil life
remain, so in order to reestablish life one must start from scratch (pioneer species
comes in and restarts the community).
example: body of water completely dries up
Secondary succession is when not all of the community has been destroyed--the
building blocks remain.
example: fire destroys most of the biotic life in a community
Why do scientists consider invasive species to be a problem? What makes a species
"invasive" and what ecological effects can invasive species have? Give examples. -
ANSWER-Invasive species often lead to problems becasue they displace the trophic
cascade of the community it "invades."
A species is invasive if it is not native and therefore does not have any traditional
limiting factors. This can result in a takeover, as the invasive species goes
unchecked and pushes organisms out of the community as it establishes itself as the
fiercest competitor.
, Book example: zebra mussel
What is restoration ecology? Why is it an important scientific pursuit in today's world?
- ANSWER-Restoration ecology is the study of life pre-industrialization and aims to
restore functionality to ecological communities typically as a result of human
disturbance.
This is very important in today's world because humans are populating and
expanding at an invasive rate. We have to correct the subsequent damage we have
caused to the environments we are developing for human purposes.
What factors most strongly influence the type of biome that forms in a particular
place on land? What factors determine the type of aquatic system that may form in a
given location? - ANSWER-Temp and precipitation are typically what determine the
type of biome that will form.
Water temp, depth, salinity, dissolved nutrients, and others help to determine the
type of aquatic system that will form in a given location.
Using the concepts of trophic levels and energy flow, explain why the ecological
footprint of a vegetarian person is smaller than that of a meat-eater. - ANSWER-At
each trophic level, organisms use energy in cellular respiration. Only a small portion
of the energy is transferred to the next trophic level (~10% of the energy of the
trophic level below it). Each amount of meat or animal product we eat requires the
input of a considerably greater amount of plant material, so energy per calorie
gained is far greater for animal products than plant products.
Describe five ecological changes to freshwater communities in the Great Lakes or
the Hudson River that have occurred since the invasion of the zebra mussel.
Describe one economic impact of the invasion. What is one way to prevent the
mussel from spreading to new areas? - ANSWER-Hudson River:
-Biomass of phytoplankton fell by 80%
-Biomass of small zooplankton fell by 76%
-Biomass of large zooplankton fell by 52%
(Overall zooplankton and invertebrate decline 70%)
-Forces different fish (young of littoral fish) upstream and (open-water) downstream
-Populations of native mussel crash (competition for food)
Economic impact: In the Hudson: Larvae decrease...could affect sport fisheries by
billions of dollars, but overall, not too bad
In the Great Lakes: $5 billion of damage in the first decade of invasion
One way to prevent the mussels from spreading to new ares: intro of new species
(quagga mussels have already reduced zebra mussels)...or drain/clean boats to
lessen the spread
Which type of feedback loop is more common in nature, and which more commonly
results from human action?
How might the emergence of a positive feedback loop affect a system in
homeostasis? - ANSWER-Negative feedback loops are far more common in nature.
Positive feedback loops are more commonly a result of human interaction. The
Complete Answers
Give examples of symbiotic and non-symbiotic mutualism. Describe at least one way
in which a mutualism affects your daily life. - ANSWER-Non-symbiotic: a cleaner fish
and the organisms they come across to "clean"
Symbiotic: bacteria living in our guts which aid in digestion (also an example of one
way mutualism affects my daily life)
Compare and contrast trophic levels, food chains, and food webs. How are these
concepts related, and how do they differ? - ANSWER-Trophic levels are the ranks of
food hierarchies. Food chains are a simple way to map the cyclical transition of
feeding from plant to herbivore to predator to bigger predator to detritivores to
decomposition and then back to plant again.
A food web is more complex than a food chain because it is not linear, more
complex, and more realistic.
The trophic levels help to classify the members of the food chains and webs into
community hierarchies. They show us how much food and energy are available to
each trophic level and then how much will be passed on (10% rule).
What is meant by the term keystone species, and what types of organisms are most
often considered keystone species? - ANSWER-Keystone species are those which
contribute so much to their environment that if removed from a community will result
in the destruction of said community. Secondary and tertiary consumers on the
trophic cascade are typically considered to be keystone.
Describe the process of primary succession. How does it differ from secondary
succession? Give an example of each. - ANSWER-Primary succession is when a
community has undergone an event so catastrophic that none of its plants or soil life
remain, so in order to reestablish life one must start from scratch (pioneer species
comes in and restarts the community).
example: body of water completely dries up
Secondary succession is when not all of the community has been destroyed--the
building blocks remain.
example: fire destroys most of the biotic life in a community
Why do scientists consider invasive species to be a problem? What makes a species
"invasive" and what ecological effects can invasive species have? Give examples. -
ANSWER-Invasive species often lead to problems becasue they displace the trophic
cascade of the community it "invades."
A species is invasive if it is not native and therefore does not have any traditional
limiting factors. This can result in a takeover, as the invasive species goes
unchecked and pushes organisms out of the community as it establishes itself as the
fiercest competitor.
, Book example: zebra mussel
What is restoration ecology? Why is it an important scientific pursuit in today's world?
- ANSWER-Restoration ecology is the study of life pre-industrialization and aims to
restore functionality to ecological communities typically as a result of human
disturbance.
This is very important in today's world because humans are populating and
expanding at an invasive rate. We have to correct the subsequent damage we have
caused to the environments we are developing for human purposes.
What factors most strongly influence the type of biome that forms in a particular
place on land? What factors determine the type of aquatic system that may form in a
given location? - ANSWER-Temp and precipitation are typically what determine the
type of biome that will form.
Water temp, depth, salinity, dissolved nutrients, and others help to determine the
type of aquatic system that will form in a given location.
Using the concepts of trophic levels and energy flow, explain why the ecological
footprint of a vegetarian person is smaller than that of a meat-eater. - ANSWER-At
each trophic level, organisms use energy in cellular respiration. Only a small portion
of the energy is transferred to the next trophic level (~10% of the energy of the
trophic level below it). Each amount of meat or animal product we eat requires the
input of a considerably greater amount of plant material, so energy per calorie
gained is far greater for animal products than plant products.
Describe five ecological changes to freshwater communities in the Great Lakes or
the Hudson River that have occurred since the invasion of the zebra mussel.
Describe one economic impact of the invasion. What is one way to prevent the
mussel from spreading to new areas? - ANSWER-Hudson River:
-Biomass of phytoplankton fell by 80%
-Biomass of small zooplankton fell by 76%
-Biomass of large zooplankton fell by 52%
(Overall zooplankton and invertebrate decline 70%)
-Forces different fish (young of littoral fish) upstream and (open-water) downstream
-Populations of native mussel crash (competition for food)
Economic impact: In the Hudson: Larvae decrease...could affect sport fisheries by
billions of dollars, but overall, not too bad
In the Great Lakes: $5 billion of damage in the first decade of invasion
One way to prevent the mussels from spreading to new ares: intro of new species
(quagga mussels have already reduced zebra mussels)...or drain/clean boats to
lessen the spread
Which type of feedback loop is more common in nature, and which more commonly
results from human action?
How might the emergence of a positive feedback loop affect a system in
homeostasis? - ANSWER-Negative feedback loops are far more common in nature.
Positive feedback loops are more commonly a result of human interaction. The
