Ecology Review Worksheet KEY
47-1
1.
Earth: A Living Planet
Define
a.
Ecology - Ecology is the study of the interactions of organisms with one another and with their physical surroundings
b.
Biosphere - Biosphere is that part of the Earth in which life exists.
c.
ecosystem - Ecosystem consists of all the biotic and abiotic factors of a given area.
2.
Give 3 examples of abiotic factors.
Abiotic factors are all the nonliving factors –soil type, rainfall, elevation, temperature, and location on the Earth 00that
surround organisms and affect them.
3.
Give 3 example of biotic factors.
Biotic factors are all the living organisms.
4.
Explain how the following paired terms are related to each other:
a.
biosphere – ecosystem
The biosphere is that part of the Earth on which life exists. The biosphere is divided into a variety of smaller units
called ecosystems
b.
ecology – biosphere
Ecology is the study of the interactions of living things with one another and with their environment. Since the
biosphere is the part of the Earth in which life exists, ecology is a study of the biosphere
c.
biotic factors – abiotic factors
Biotic factors are all the living organisms in an ecosystem. Abiotic factors are the nonliving factors such as
temperature, rainfall, soil type, elevation, and location on the Earth. Together, they make up an ecosystem
d.
ecological succession – climax community
In ecological succession, an existing community is gradually replaced by another community. This process often leads
eventually to a relatively stable collection of plants and animals called a climax community. Thus, the climax
community is the final stage of ecological succession
e.
community – ecosystem
A community is a group of organisms living in a common environment and interacting with one another. The
organisms that make up a community are the biotic factors in an ecosystem
5.
Describe the process of ecological succession.
In ecological succession, an exisiting community of organisms is gradually replaced by another community.
6.
What is a climax community?
A climax community is a relatively stable collection of plants and animals and is usually described by the major forms of plant
life.
7.
What determines the type of climax community that forms?
The type of climax community would depend on the climate and geography of the are. It would also depend on the type of plants
near the area.
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8.
The pictures below show 4 stages in the development of n ecological community on the site of an
abandoned farm. These stages are NOT in order.
a.
Indicate the order of pictures from the earliest stage to the last: B, D, A, C
b.
What kinds of plants might be associated with the climax community in this area?
Large deciduous trees, such as maples, oaks, and birches
c.
Suppose a site similar to this one was mowed twice a year. What kinds of plants would you expect
to find on such a site? Explain why:
We would expect to find grasses and small wildflowers, because the constant mowing would keep slower-growing plants
such as shrubs and trees from gaining a foothold, and would thus halt the process of succession
9.
How would the breakdown of large amounts of organic matter upset the natural balance of a lake
ecosystem?
The breakdown of large amounts of organic matter would encourage the growth of algae and other organisms. In turn, the lake
would probably be replaced by a marsh and then by dry land.
47-4
1.
Energy and Nutrients: Building the Web of Life
Define and give an example of the following:
a.
producer - Organism that is able to make its own food from inorganic substances
2.
b.
primary consumer - Organism that gets its energy either directly from producers
c.
secondary consumer - Organism that gets its energy either indirectly from producers
d.
decomposer - Organism that breaks down and obtains energy from dead organic matter
The terms in each of the following groups are related to one another. For EACH group
a.
State the relationships that exist among the terms
i.
producers, consumers, decomposers
Definitions:
Producer:
Organism that is able to make its own food from inorganic substances
Consumer:
Organism that gets its energy either directly or indirectly from producers
Decomposer:
Organism that breaks down and obtains energy from dead organic matter
Relationships:
Consumers eat producers, or other consumers. Decomposers break down the remains of both producers and
consumers.
Producers provide the energy for both other groups, while decomposers make nutrients available for both other
groups.
ii.
trophic level, ecological pyramids
Definitions:
Trophic level:
“Feeding level”: a step in the series of organisms eating other organisms in an ecosystem
Ecological pyramids: Diagram used to represent the energy relationships among the different trophic levels of
an ecosystem
Relationships:
Ecological pyramids are used to graphically illustrate the energy relationships among the different trophic levels
of an ecosystem.
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3.
Explain in your own words how the movement of nutrients in an ecosystem is different from the
movement of energy in an ecosystem.
Nutrients (such as nitrogen, carbon, etc.) STAY within an ecosystem as they are recycled, whereas energy FLOWS
THROUGH an ecosystem as it is passed from one organism to another, with significant loss at each transition. Thus,
nutrients are conserved and used again, whereas energy is not.
4.
Describe the three types of ecological pyramids.
A pyramid of energy show the total amount of incoming energy at each successive trophic level.
A pyramid of mass shows the total mass of living tissue at each trophic level.
A pyramid of numbers shows the total number of organisms at each trophic level.
5.
Give an example of a food chain.
Sun  grass  cow  Mrs. Kusec
6.
Compare a food chain and a food web.
A food chain is a sequence of organisms in which each individual feeds on the next. A food web is the union of interrelated food
chains.
7.
Imagine that you have just eaten a tuna sandwich, an apple, and a glass of milk. Draw a possible food chain
for each item listed above. Indicate which order you are in each chain.
Possible answers:
Sun  phytoplankton  zooplankton  anchovy  TUNA  person
Person is a 4th order (quaternary) consumer
Sun  APPLE TREE  person
Person is a 1st order (primary) consumer
Sun  hay  COW  person
Person is a 2nd order (secondary) consumer
48-1
1.
Population Growth
Define a population.
A population is a group of organisms of the same species that live in the same area.
2.
Give 3 examples of a population in our area.
Chipmunks, humans, cats
3.
How do exponential growth and logistic growth differ?
Exponential growth is not sustainable and organisms run out of nutrients. Logistic growth is much more realistic in
populations.
4.
Describe the five stages of a logistic growth curve.
At first, growth is exponential, starting slowly and then growing rapidly through phase. During phases 3 and 4, the population
growth begins to slow down. Finally, when the population reaches the carrying capacity of the ecosystem, the population reaches
a steady state.
5.
What is the relationship between population growth and carrying capacity?
Populations growth will continue until it reaches the carrying capacity. The carrying capacity represents the optimum number of
organisms of a particular species that can be supported by a particular environment.
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6.
The graphs below represent two different types of population growth. Use the graphs to answer the
questions that follow.
a.
On the blank lines above the graphs, give each graph a title based on the type of population growth
it depicts.
b.
On each graph, what does the horizontal axis represent? Label it appropriately.
Time
c.
What does the vertical axis represent? Label it appropriately.
Number of organisms
d.
On Graph 2, what does the area between points E and F represent? Label this area. Steady state
e.
On Graph 2, what does line 1 represent? Label accordingly.
f.
Describe, in your own words, what is happening to the population in Graph 1.
The population is growing rapidly without ecological resistance. The larger the population gets, the faster it grows
Carrying capacity
7.
Each of the statements below refers to exponential population growth (E) or logistic population growth (L).
In the blank next to each statement, label accordingly.
a.
__L___
A lack of food prevents a certain population from growing any further.
b.
__L___
In the stead state, the average growth rate is zero.
c.
__E___
The larger the population gets, the faster it grows.
d.
__E___
One pair of elephants could produce 19 million descendants in less than 750 years.
e.
__L___
A particular environment is limited to a certain number of rabbits that it can
support.
f.
__E___
All of the offspring of a given population survive and reproduce.
8.
Use the concept of carrying capacity to explain the importance of conservation.
Since the growth of populations in all species is dependent on limiting factors, the conservation (the wise management of
resources) will provide for the future growth of the population.
48-2:
1.
Factors That Control Population Growth
Define density-dependent limiting factors. Give three examples.
Factors include competition (organisms vying for the same food, space, and so on), predation (organism feeding on other
organisms), and parasitism (one organisms living off another organism)
2.
Define density-independent limiting factors. Give three examples.
Density-dependent limiting factors (predation and so on) tend to acct on large populations, and density-independent limiting
factors (storms, floods, and so on) act on populations of any size.
3.
What effects do the following have on population growth? Give an example of each.
a.
competition – the population would decrease for one species but increase for another. All the fast mice would survive
and the slow mice would die.
b.
predation – the population would decrease on the prey. All the mice would die if the weasels ate them.
c.
parasitism – the population would decrease on the hosts. All the fleas would be happy on the mice but the mice
would become weaker and be less successful in reproducing.
d.
overcrowding - the population would decrease. The mice population would decrease due to a lack of food or space.
e.
natural catastrophes – the population would decrease. All the mice and weasels die in a volcanic eruption
4.
Each of the statements below describes a situation that affects population growth. Some describe densitydependent factors (D) whereas others describe density-independent (I) factors. Label accordingly.
Mrs. Kusec Biology 11
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
5.
__I___ A severe frost wipes out 50% of the citrus crop in southern Florida.
__D___Since snakes prey on frogs, an increase in the frog population causes an increase in the
snake population.
__D___Due to sever overcrowding in an African village, many children do not survive to reach
adulthood
__I___ The eruption of Mt. St. Helens destroys most of the wildlife in the immediate vicinity of the
volcano.
__I___ Off the coast of Peru, many fish die due to a change in the winds and the movement of
ocean currents.
__D___Two animals attempt to occupy the same niche. The moe aggressive animal survives, and
the other does not.
__D___Because rabbits in Australia have no natural enemies, their population increases
exponentially.
__D___Travelers who venture into a crowded Afghani refugee camp become infected with a
disease caused by parasites.
__D___Fish on a coral reef stake out their territory and chase away any younger fish that try to live
there.
__D___Due to stress, large numbers of female mice miscarry their young and fail to reproduce.
The graph below shows a predator—prey relationship. Use the graph to answer the questions that follow.
a.
What is happening to the predator population between points c and d on the graph?
The population is increasing to its maximum
b.
What is causing this to happen?
The prey population recently increased to its maximum, so predator survival has improved as they respond to an
abundance of prey
c.
What is happening to the predator population at point e? Why is this happening?
The predator population is decreasing because prey are becoming scarcer
d.
What is happening to the prey population at point b? Why is this happening?
The prey population is increasing because the predator population has declined, and more prey survive to reproduce
e.
Suppose that human activity were to wipe out a large number of predators between points c and d.
Predict what would happen to the prey population between points c and e.
Without heavy predation, the prey population will continue its pattern of increase seen between c and d
6.
How does the evolution of a successful defense mechanism in a species of prey increase the chances of
survival for a species of predator that uses the prey for food?
48-3:
1.
Interactions Within and Between Communities
What is a community?
A group of populations living in a given area.
2.
How do populations in a community interact?
Populations within a community interact through competition, predation, and so on.
3.
Define and give an example of:
a.
parasitism - In parasitism, one organism beneftis and the other is harmed.
b.
commensalisms - In commensalism, one organism benefits and the other does not benefit nor is it harmed.
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c.
mutualism - In mutualism, both organism benefit.
4.
Do ecosystems operate independently of one another? Describe some ways in which ecosystems are
interconnected.
Ecosystems do not act independently.
5.
What is an adaptation?
It is a process that enable organisms to become better suited to their envionments.
6.
How can an adaptation be beneficial? How can an adaptation be detrimental?
A adaptation can be beneficial because an organism is best fitted to survive in the environment. For example, it can become
very efficient at finding food.
Adaptation can be detrimental because an organism is too well fitted to a specific environment and cannot adapt to changes.
For example, it can only find one type of food.
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