CHAPTER
3
Self-Quiz
SUGGESTED ANSWERS
1.
(b); Choice (b) is correct because an established forest ecosystem that supports animal and plant life would
have relatively constant conditions over a period of time. Choice (a) is incorrect. On an island that has
just been hit by a hurricane, the ecosystem conditions would have changed drastically from those in place
before the hurricane struck. Choice (c) is incorrect. Any area that is experiencing warming temperatures
is not in equilibrium. The temperature changes will alter conditions in local ecosystems. Choice (d) is
incorrect. A fire would wipe out the existing ecosystem. A year after the fire, a new ecosystem would begin
to establish itself, and it would be different from the system in place before the fire.
2.
(a); Choice (a) is correct. Mechanical control of an invasive species includes the use of physical barriers
and physical removal of the plant or animal. Choice (b) is incorrect. Applying pesticides to control
invasive species is a form of chemical control. Choice (c) is incorrect. Although educating people
about invasive species can be beneficial, it is not a mechanical control method. Choice (d) is incorrect.
Introducing a new species to control an invasive one is a biological method of control.
3.
(c); Choice (c) is correct. Bioremediation is the use of bacteria that consume and break down
environmental pollutants, such as oil from oil spills. Choice (a) is incorrect because it describes biological
control of invasive species. Choice (b) is incorrect because it describes an example of succession, not
bioremediation. Choice (d) is also incorrect. Collecting organisms for commercial use, such as harvesting
plants, is one way we use the products of ecosystems.
4.
(b); Choice (b) is correct because climate change affects the entire globe at an increasing rate. Even
if we could stop all greenhouse gas emissions tomorrow, the effects on climate would continue for
many decades. Choice (a) is incorrect. Although invasive species constitute a serious threat to Earth’s
ecosystems, they affect only certain areas of the globe, not the entire globe. Choice (c) is incorrect.
Habitat fragmentation is another serious threat to Earth’s ecosystems, but it does not affect the entire
globe. Choice (d) is incorrect. Air and water pollution are serious threats to Earth’s ecosystems, but their
effects may be limited. These effects can be addressed by methods such as filtration and special processing.
5.
primary; Primary succession occurs when gradual changes take place after a major disturbance, such as a
tsunami.
6.
acid precipitation; When sulfur dioxide or nitrogen oxides combine with water vapour in the atmosphere,
they form acids. These acids enter the water cycle and return to Earth as acid precipitation.
7.
equilibrium; If a community is at equilibrium it will have relatively constant conditions over long period
of time.
8.
False. When a non-native species is introduced to a new environment, it will usually fail to adapt to
the new conditions. Only occasionally will a non-native species become invasive. A true version of the
statement would be: Only a few non-native species will be able to survive in their new environment and go
on to harm native species.
9.
False. Decreasing the concentration of a pollutant allows the pollutant to spread over a larger area. The
effects of the pollutant will not be as severe, but it will still harm the environment. A true version of the
statement would be: Decreasing the concentration of a pollutant will make its effects less severe, but it will
not prevent the pollutant from harming the environment.
10.
148
False. Human actions have caused many species to become extinct, but they are not the only causes for
species extinction. Extinction is a natural process. Natural extinctions on Earth have been going on for
millions of years. A true version of the statement would be: Human actions have increased the rate of
species extinction on Earth.
Unit B: Sustainable Ecosystems
55219_03_ch03_p101-150_pp4.indd 148
NEL
12/3/09 1:37:35 PM
11. (a)(iv) Acid rain dissolves concrete, marble, and limestone used to make statues and buildings;
(b)(i) Marine animals may mistakenly eat pieces of plastic, which can interfere with and block their
digestive systems; (c)(v) When oil from spills covers the feathers of birds or the fur of seals, these animals
lose their ability to insulate themselves from the cold; (d)(ii) Clear-cutting of forests exposes large areas of
soil to wind and rain, subjecting these areas to erosion; (e)(iii) Invasive species may carry disease-causing
organisms, such as West Nile Virus, to areas that previously were not exposed.
12.
Wetlands have deep, nutrient-rich soil, which is ideal for farmland.
13.
Sample answer: Plant communities protect the soil from wind and water erosion. Plants also absorb rain
water, filter it, then slowly release it into ground and surface water systems.
14.
Students should design an advertisement for activities that are appropriate in their province, such as
a guided backpacking trip to a wilderness area. They should include pictures and a description of the
activities offered on the tour.
15. (a)
(b)
16.
Sample answer: In my neighbourhood, there are sparrows, blue jays, and robins. Most trees are oak,
sycamore, and maple trees. The most common insects are honeybees, wasps, grasshoppers, and ants.
The only wild mammal I see in my neighbourhood is the squirrel.
Sample answer: My neighbourhood does not have high species richness because it does not provide the
type of habitat needed for many different species to live here.
Sample answer: I can remind my family to take reusable shopping bags with them when they go shopping.
I can take my family’s plastic bags to a local recycling center.
17. (a)
Sample answer: Being a good steward of my natural environment means that I should use natural
resources wisely. A good steward also respects and protects plants and wildlife.
(b)
Sample answer: I should conserve water at home. When I go hiking in a wilderness area, I should
always stay on the marked trails to avoid damaging the local plant life.
18.
Sample answer: I would tell them to consider setting aside land for one large park rather than a few smaller
ones, because larger areas will support larger and more stable wildlife communities. I would tell them to
place the parks away from major streets and highways, because limiting the parks’ exposure to main roads
will help decrease the amount of pollution caused by heavy vehicular traffic.
19.
Succession allows ecosystems to recover from many types of disturbances. However, some disturbances,
such as pollution from human activities, may cause such severe environmental damage that succession
alone cannot help the ecosystem recover. When the damage is too great, humans must reduce the pollution
and help remove its causes before succession can enable the ecosystem to begin recovery.
20.
Sample answer: My family visited Point Pelee National Park summer. I saw several different types of
ecosystems and saw wildlife that I’ve only seen in pictures. This experience helped me understand that
species are dependent on each other for survival.
21.
Students may draw a diagram of any type of system (ecosystem, biological system, chemical system, etc.) in
equilibrium. The diagram and labels should clearly show that the conditions within the system are dynamic but
remain in equilibrium. An example of a system in equilibrium would be a diagram of a lake that shows water
flowing in at the same rate as it flows out, or a biome with steady biotic and abiotic features. For example:
NEL
55219_03_ch03_p101-150_pp4.indd 149
Chapter 3 Natural Ecosystems and Stewardship
149
12/3/09 1:37:35 PM
Sun
Energy outputs
radiate from Earth
Nutrients
Energy inputs
from the Sun
Earth
22.
Sample answer: I can make sure that any new vegetation that my family plants is native to our region.
I can research a non-native, invasive plant species that grows in our community, and, if possible, organize
a group to help remove it from local parks and natural areas.
23. (a)
Sample answer: Feeding the deer may cause the deer to stay closer to human homes, thereby increasing
their risk of being struck by cars or other vehicles. These accidents could harm people as well as deer.
(b)
Sample answer: No, I do not think it is wise to feed deer living in and around one’s neighbourhood. It
may discourage deer from migrating to find food, putting them at risk in the future.
24. (a)
Sample answer: Future scientists may find large amounts of plastics in our community’s landfill. This
would make them think we were not good stewards of the environment because we threw away so
much of a material that was not biodegradable and polluted the environment for many years to come.
(b)
Sample answer: I would like future scientists to discover that our community’s landfill had a liner that
limited the leaching of pollutants from the site into the surrounding environment.
25.
Sample answer: I think we must protect fragile natural features so that they last for future generations
to enjoy. If we must limit the number of visitors to a particular site, it is a small price to pay in order to
protect and preserve it.
26.
Sample table:
Type of Logging
150
Costs
Benefits
Clear-cutting
cost to forest: takes a long time for forest to
recover; forest will be even-aged and less
diverse
benefit to loggers: most economic and efficient
option
Shelterwood cutting
cost for loggers: more costly than clear-cutting
benefit for forest: more natural regeneration
is possible; forest will be more diverse than in
clear-cutting
Selective cutting
cost for loggers: most costly option
benefit for forest: has the least impact on the
ecosystem; forest will remain diverse.
Unit B: Sustainable Ecosystems
55219_03_ch03_p101-150_pp4.indd 150
NEL
12/3/09 1:37:35 PM