Transcript Answers to Check Your Understanding Questions

1. Large ecosystems include forests, deserts, oceans, and Earth as a whole.
Small ecosystems include a spruce tree, the human body, an urban park,
a pond, or a rotting log.
2. a healthy environment that endures and supports a variety of organisms
3. Sustain means to endure and to support.
4. Ruby-throated hummingbirds live part of the year in a tropical rain forest, and then
they stop in many ecosystems along the way as they migrate north in the spring.
They spend the summer in meadows and wetlands in Canada.
5. Eels eat insects, crustaceans, fish, frogs, and dead animals. They are prey for
other fish, birds, and mammals. Both saltwater and freshwater species and their
ecosystems are affected by a decrease in the eel population.
6. Symbiosis is the interaction between members of two different species that live
together in a close association.
7. Predation occurs when one organism (the predator) consumes another organism (its
prey) for food. Competition occurs when two or more organisms compete for the
same resource, such as food, in the same location at the same time. The relationship
between predators and their prey can influence the population of both the predator
and the prey, as well as affect the entire ecosystem in which they live. Competition
can influence the population size and success of a group of organisms. Sometimes,
one group of organisms is outcompeted by another group.
8. Biotic parts could include people, pets, houseplants, crops, grass, insects, and
bacteria.
9. Students can describe any three of the following: water, light, oxygen, nutrients,
And soil. Accept any reasonable response regarding the effect that human
activity could have on the abiotic part.
10. The abiotic features of temperate deciduous forests include receiving between
75 cm and 180 cm of precipitation per year, equally distributed throughout the year.
Seasonal changes between summer and winter are very large. Temperatures range
from –30°C in winter to 30°C in summer. Temperate deciduous forests have four
distinct seasons and a long, warm growing season. Fallen leaves that break down
and release nutrients enrich the soil in temperate deciduous forests. The main
biotic feature of temperate deciduous forests is trees that lose their leaves during the
winter. The forest has a complex structure that consists of plants that grow in four
to five layers. The many layers in the forest provide a variety of habitats for squirrels,
rabbits, skunks, cougars, deer, wolves, bears, and amphibians. Squirrels, chipmunks,
and blue jays store nuts and seeds in tree hollows. Some mammals hibernate. Many
birds migrate to warmer areas in winter.
11. acid precipitation and clear cutting the forests
13. Sustainable ecosystems provide ecosystem services that all living
things depend on for survival.
15. Tree roots help hold soil in place, reducing erosion.
17. (a) competition
(b) predation
(c) symbiosis
Key Terms
Ecosystem- all the interacting parts of a biological community and
its environment
Sustainable ecosystem – an ecosystem that is capable of withstanding
pressure and giving support to a variety of organisms
Biotic
-Symbiosis
-predation
-competition
Abiotic
-water
-oxygen
-light
-nutrients
-soil
Answers to Check Your Understanding Questions
(Student textbook page 290)
1. Populations tend to increase when individuals reproduce at rates that are
greater than what is needed to replace individuals who have left the area or
died and/or when potential limiting factors are not limiting.
2. Even within the protected confines of the park, exponential growth cannot be
sustained. Eventually a limiting factor such as space, food, a disease, or water
will limit the population growth.
3. nutrients, space, light, predators, or dissolved oxygen (in aquatic ecosystems)
4. Resources that quickly became limited were gasoline, other fuels, water (if
electrically pumped), some food (refrigerated), batteries, candles, and so on.
Section 7.2 Review Answers (Student textbook page 301)
1. A population is a group of organisms of one species that lives in the same
place, at the same time, and can successfully reproduce. An example of a
population would be humans living in Halifax.
2. Exponential growth cannot continue for long in nature because no ecosystem
has an unlimited supply of the things that organisms need. These restrictions
are known as limiting factors.
3. Limiting factors include abiotic factors such as water, food, light, space, and
soil, and biotic factors such as symbiosis, predation, and competition.
4. Both are limiting factors on population growth. A density-independent factor is
any factor in the environment that does not depend on the number of members
in a population per unit area. These factors are usually abiotic and include natural
phenomena such as weather events—extreme storms, droughts, floods, fires,
cold snaps, and heat waves. A density-dependent factor is any factor in the
environment that depends on the number of members in a population per unit
area. These factors are usually biotic factors such as disease, parasites,
predation, and competition.
5. Carrying capacity is the size of a population that can be supported
indefinitely by the resources of a given ecosystem. Students may choose to
use a graph to show how a population undergoes exponential growth then
levels off, reaching carrying capacity.
6. The squirrels need dead trees in which to roost. The loss of dead trees could
be a limiting factor for the population and reduce the carrying capacity of the
population.
7. An ecological niche is the way an organism occupies a position in an
ecosystem, including all the necessary biotic and abiotic factors.
8. An ecological niche is like a job because organisms must go about the
business of surviving and reproducing and in doing so provide services to the
ecosystem. It is not like a job in the sense that organisms do not have
obligations or responsibilities to their ecosystems.
9. The plants are carnivorous. They capture and consume insects. Bogs have
relatively acidic soil and water, and they are nutrient-poor environments.
10. We have been able to redefine and expand our niche, allowing us to go
everywhere on the globe. By learning to control energy and resources, we have
increased the biosphere’s carrying capacity for humans, at least for now.
11. by increasing the availability of energy and resources for consumption, or by
reducing consumption
12. Sustainable use of a resource is use that does not cause long-term depletion
of the resource, or affect the diversity of the ecosystem from which the resource
is obtained. Unsustainable use is a pattern of activity that leads to a decline in the
function of an ecosystem.
13. Many scientists currently place human carrying capacity at about 12 billion
people.
14. The population undergoes exponential growth between 0 and 80 days, then
begins slowing down toward its carrying capacity. After 90 days, the population
growth is in equilibrium. Possible limiting factors for the population could include
food and space.
15. The niche would shrink over time.
16. Students may describe street boundaries, neighbourhood, school, and/or their
home. Their niche may include places where they regularly shop, visit, or play
sports. A sketch would contain similar information. It would be interesting to
compare the different sizes and complexities that students come up with.
17. Toes: recycle, reuse, compost, ride a bicycle, am a vegetarian, grow
vegetables, take short showers; Heel: do not eat imported fruits and vegetables;
Middle: get a ride to school every day
(b) largest: United States and United Arab
Emirates; smallest: Afghanistan and
Ethiopia
(c) Differences occur due to the way
resources are being used. There may be a
conscious effort to reduce the footprint
through sustainable use of resources, or
simply a lack of resource use making a
footprint low. For countries with large
footprints, resources are plentiful and may
not be used in a sustainable manner.
Answers to Check Your Understanding Questions
(Student textbook page 303)
8. Eutrophication is a process in which nutrient levels in aquatic ecosystems
increase, leading to an increase in the populations of primary producers.
9. Phosphorus was found to be the main cause of eutrophication.
10. fertilizer in run-off
11. In order to get the lawn looking healthy, you probably added fertilizer. The
fertilizer improved the lawn, but it also leached into the pond, causing
eutrophication and an algae bloom that depleted the oxygen and therefore killed
the fish.
Answers to Check Your Understanding Questions
(Student textbook page 308)
12. The greenhouse effect occurs because greenhouse gases trap heat within
Earth’s atmosphere. This effect keeps Earth considerably warmer than it
otherwise would be, allowing life to flourish.
13. Answers should include the idea of ways to reduce the use of fossil fuels,
such as carpooling, walking, or biking instead of driving in a car, or turning off
lights when you leave a room.
14. A trophic level is a category of organisms that is defined by how the
organisms gain energy. Trophic efficiency is a measure of how much of the
energy in organisms at one trophic level is transferred to the next higher trophic
level.
15. Bioaccumulation is a process in which materials, especially toxins, are
ingested by an organism at a greater rate than they are eliminated.
Answers to Check Your Understanding Questions
(Student textbook page 318)
1. Ecosystem services are the benefits sustainable ecosystems provide that are
experienced by living organisms, including humans.
2. Forests take in large amounts of carbon dioxide from the atmosphere as part
of photosynthesis. In recent years, scientists have looked at the importance of
forests as carbon sinks for the increased carbon dioxide in the atmosphere due
to the burning of fossil fuels.
3. Any two of the following: Forests act as sinks for carbon dioxide, cutting down
forests would reduce this sink and possibly increase the effects of climate
change as more carbon dioxide enters the atmosphere. Forests reduce erosion
in watersheds, so cutting them down can lead to an increase in erosion and an
increase in the amount of nutrients in run-off reaching aquatic ecosystems.
Forests provide a habitat for thousands of species; cutting them down could
reduce biodiversity.
4. The amount of nitrogen in run-off from a cleared watershed was 60 percent
higher than the amount of nitrogen in run-off from an uncut watershed. This
means that excess nutrients could reach aquatic ecosystems and cause algal
blooms, which can eventually lead to the death of fish and other aquatic
organisms.
Answers to Check Your Understanding Questions
(Student textbook page 322)
5. pollination
6. Pesticides may affect the ability of honeybees to find their way back to
their hives. As a result, the bees leave their hives and never return. A
parasite called the Varroa destructor mite attaches itself to the outside of
honeybees and feeds off their fluids. Another mite, called the honeybee
tracheal mite, attaches to the tracheas of honeybees and suffocates them.
Transportation of colonies over long distances can affect honeybees.
Confinement or the temperature and vibrations on trucks may
disrupt the bees’ life cycle.
7. Many people find a sense of spirituality in the beauty of nature. Many
Aboriginal peoples continue spiritual traditions that are connected to nature.
Answers to Check Your Understanding Questions
(Student textbook
page 327)
8. Biodiversity includes the number and variety of organisms found in a
specific region.
9. When biodiversity is high (or higher relative to other ecosystems), the
resilience of the ecosystem is also high.
10. Deforestation can threaten the biodiversity of an ecosystem. Biologists
estimate that tropical rainforests contain about half of all the species on Earth.
(This estimate could be significantly low. The total number of species on Earth is
itself an estimate, and new species unknown to science—especially those that
live in tropical forests— are discovered each year.) As well, annual deforestation
rates in the boreal plans of Canada from 1966 to 1994 were almost three times
the average rate of deforestation worldwide, with forest cover decreasing by up
to 55 percent during that time. Researchers at Environment Canada have found
that along one of their survey routes in this ecosystem, the number of bird
species declined from a maximum of 105 species in 1987 to only 67 species by
1995.
11. Wetlands are often drained for farming or for building houses and other
buildings. Sometimes, they are drained for mosquito control.
Answers to Check Your Understanding Questions
(Student textbook page 340)
15. A paradigm is a view of the world or a way of thinking about how the
world works. A paradigm shift requires that people change their way of
thinking about a subject. Because of this, there is often resistance to a
change in the paradigm. Although controversial when first presented,
paradigm shifts eventually come to be accepted as major advancements in
scientific knowledge and understanding.
16. Students may choose from one of the following paradigm shifts: shifting
from the geocentric model of the universe to the heliocentric model, shifting
from the theory of spontaneous generation to the theory of biogenesis, or
shifting from the idea that the continents and ocean basins were in fixed
positions on Earth and did not move to the theory of plate tectonics.
Flowcharts should reflect clear steps involved in whichever shift students
chose.
17. The shift involves the way people view the sustainability of ecosystems and
the use of resources on Earth. The shift involves the way people think about the
consequences of our actions and how our actions affect our ecosystems and all
of Earth’s systems—the biosphere, the atmosphere, the hydrosphere, and the
lithosphere. The shift involves the idea that people are starting to see that
ecosystems and Earth’s systems are connected and that a change made to one
system can have effects, sometimes far-reaching, in another system.
18. Students may choose from any two of the following: Many local, provincial,
national, and international governments already participate in ways to reduce
carbon dioxide concentration in the atmosphere, such as signing the Kyoto
Protocol. They support reduce, re-use, and recycle campaigns, promote the use
of public transportation, and produce and promote the use of alternative sources
of energy. Governments are also working to reduce the impact and introduction
of invasive species, educate their citizens about environmental issues, and sign
treaties or agreements that will help improve the status of endangered or
threatened species or ecosystems. Many non-profit organizations, such as
UINR, also advocate for changes to protect the environment and Earth’s
systems. Student may also choose more specific examples from Table 8.2.
Answers to Check Your Understanding Questions (Student textbook page 343)
19. Scientific research has shown that many pesticides are toxic to humans and
wildlife. Pesticides such as DDT can bioaccumulate in the tissues of living
organisms. Exposure to various pesticides through air and water has been linked
to cancer, nervous system disorders, increased cases of asthma, and the
decline of populations of frogs and other amphibians.
20. Farmers volunteer to be part of a program in which particular environmental
impacts of a family’s farm are examined. Then a plan to reduce some of these
impacts is developed. Aspects of sustainability that may be considered in an
EFP include nutrient management (including nitrogen and phosphorus), soil
management, irrigation management, wildlife habitats, and pesticide use.
21. Idling control by-laws help reduce the amount of time vehicles spend idling,
which reduces the emission of greenhouse gases from vehicles. This can help
lessen the effects of global climate change, as well as improve air quality within
a region.
22. BPA is a chemical used in food packaging such as hard plastic bottles, the
lining of aluminum cans in which food and beverages are sold, and plastic
baby bottles. Reducing its use could improve the sustainability of ecosystems
as studies have shown that aquatic animals exposed to BPA may have
reduced reproductive success, deformed embryos, and altered mating
behaviour. As well, evidence from studies shows that it can mimic the estrogen
hormone in animal systems and act as an endocrine disruptor.