CHAPTER
4
Review
SUGGESTED ANSWERS
WHAT DO YOU REMEMBER?
1. (a)
(b)
natural
(c)
pesticides
(d)
bioaccumulate
(e)
narrow-spectrum
(f)
integrated pest management
(g)
monoculture
(h)
engineered
2. (a)
3.
natural
(b)
monoculture
(c)
monoculture
(d)
monoculture
(e)
monoculture
(f)
monoculture
Sample answer: The distinguishing features of an urban ecosystem include ground covered by buildings
and roads, few species of plants present, and a reliance on other ecosystems for food and waste disposal.
4. (a)
5.
pest
v; (b) iv; (c) iii; (d) i; (e) ii
Sample answer: Non-native food supplies: corn, wheat, potatoes, beans, barley, rye, oats, soybeans, canola,
tomatoes. Native food supplies: strawberries, maple sap, wild rice, blueberries, turkeys
WHAT DO YOU UNDERSTAND?
6. (a)
(b)
Sample answer: A broad-spectrum pesticide is useful because it can be used to kill a wide variety of
pests in one application; the disadvantage is that it may kill helpful species as well. A narrow-spectrum
pesticide is targeted to a limited number of species, so it will not kill helpful species, but a farmer may
need to use several different narrow-spectrum pesticides to kill all of the pest species that are present.
Sample answer: Broad-spectrum pesticides are best for when you do not know what the pests are.
Narrow-spectrum pesticides would be preferred when you know the pests and they are only a few species.
7.
Sample answer: Modern tools and machinery, and concentrated energy sources are the two innovations
that given humans the ability to dramatically alter their environments.
8.
Sample answer: Most human food comes from engineered ecosystems because humans require food
produced on a large scale.
9.
Sample answer: high biodiversity vs. low biodiversity, natural vs. human engineered, intact food webs vs.
altered food webs, low use by humans vs. intensive use by humans, variable abiotic features vs. uniform
abiotic features, sustainable vs. not sustainable, no chemical use vs. use of fertilizers and pesticides; natural
biogeochemical cycles vs. human-altered biogeochemical cycles
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10.
Sample answer: Soil is a complex mix of minerals, water, dissolved nutrients, air, and decomposing organic
matter.
11.
Sample answer: Leaching causes problems for farmers because it removes nutrients from soil. It is a
problem for other ecosystems, because the nutrients that are removed from farmland via leaching can cause
algal blooms in aquatic ecosystems.
12.
Sample answer: Farmers need to control water availability when the naturally occurring amount of water
in an ecosystem is more or less than is required by the crops grown there. Irrigation can be used to add
water to an ecosystem; drainage tiles remove water from saturated soil.
13.
Sample answer: The application method shown can lead to pesticides entering the soil and leaching into
other ecosystems. Also, all plants are sprayed even if they do not all have pests, so more pesticide is used
than is needed.
14.
Sample answer: The advantages of not using pesticides include the preservation of non-target species, and
avoidance of problems with bioamplification, bioaccumulation, and pesticide resistance. Also, pesticide
threats to humans are avoided.
15.
Sample answer: No-till techniques reduce soil compaction and reduce erosion. Sometimes they require use
of extra pesticides.
16.
Sample diagram:
Secondary consumers 20 000 ppb
Primary consumers 200 ppb
Producers 20 ppb
Toxins dissolved in water 0.02 ppb
17.
Sample answer: Monocultures are not sustainable because biodiversity is greatly decreased and natural food
webs are destroyed.
SOLVE A PROBLEM
18.
Sample answer:
Natural
Ecosystems
Engineered
Ecosystems
high biodiversity
low biodiversity
intact food webs
photosynthesis
altered food webs
sustainable
similar climate
not sustainable
no chemical use
producers and
consumers
present
fertilizerse and
pesticides
natural
biogeochemical
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human-altered
cycles
Chapter 4 Ecosystems by Design
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19.
Sample answer: Dandelions in my yard are pests; they can be controlled by digging them up. Beetles in the
pantry are pests; they can be controlled with insecticides or better cleaning and sealing of food. Algae in
my fish tank is a pest, it can be controlled by reducing the amount of light, cleaning the glass and gravel,
and ensuring good water quality (to reduce nutrient build up). Fleas on my dog can be controlled with flea
powder or a drug. Mosquitoes in the cottage at night can be controlled by better screens and not leaving
the door open—they can also be “swatted.”
20.
Sample answer: No, soil is not an abundant resource. It is the part of Earth that is easily visible to us, so it
may seem abundant, but the layer of soil covering Earth is very thin and soil is very slow to regenerate if it
is destroyed or eroded away.
21.
Sample answer: Yes, plastic bottles should be banned everywhere. People can plan ahead and use reusable
containers for drinks. Although plastic can be recycled, it is not good for the environment.
CREATE AND EVALUATE
22.
Sample answer: No, golf courses should not be exempt from legislation regarding cosmetic pesticide use.
There is no reason why different plant species, even those considered pests, cannot be a part of a golf
course. Problem weeds could be controlled by mechanical means.
23.
Sample answer: Pesticides and fertilizers increase crop yields, so products grown using these chemicals are
usually less expensive.
24.
Sample answer: If more people lived in rural settings, the use of fuel and resulting air pollution would
increase due to the increased need for people to drive long distances for work, shopping, etc.
REFLECT ON YOUR LEARNING
25.
Sample answer: Crops grown in monoculture are among the least sustainable human-engineered
ecosystems. They require constant management of the abiotic conditions in order to thrive.
26.
Sample answer: Choices about waste disposal and transportation are most important in making a
community more sustainable. Waste disposal is an area where individuals can greatly change their
habits and make an impact. The wise use of transportation impacts both resource use and production of
pollution.
27.
Sample answer: Yes, I have learned about the unintended consequences of the use of these chemicals,
making me encourage my family to buy organic produce whenever possible.
WEB CONNECTIONS
28.
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Answers will vary based on students’ research. Students may learn that Canada geese can produce a lot of
waste in public spaces because they like feeding on grass in parks. This can be unsightly and unhealthy.
Raccoons can become a nuisance if they start getting into people’s garbage or taking up residence in attics.
Raccoons also have the potential to carry rabies.
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