CHAPTER
4
Self-Quiz
SUGGESTED ANSWERS
1.
(c); Choice (c) best describes bioaccumulation, which happens when pesticides collect, or accumulate, in
an organism. Choice (a) is incorrect. Bioaccumulation does not necessarily mean that a species will build
up resistance to pesticides. Choice (b) is incorrect because it refers to pesticides in the soil, air, and water.
It does not mention the build-up of pesticides in living things. Choice (d) is incorrect because it describes
bioamplification, not bioaccumulation.
2.
(a); Choice (a) is correct. Ammonia-based fertilizers are manufactured using synthetic chemical processes.
Choice (b) is incorrect because manure is a natural product of organisms. Choice (c) is also incorrect.
Compost consists of decaying organic matter. Choice (d) is incorrect because rotenone is a natural toxin
used as a pesticide.
3.
(b); Choice (b) is correct. In no-tillage agriculture, farmers do not plough the remaining vegetation after
a harvest. Choice (a) is incorrect. Farmers who use no-tillage agriculture sometimes use more pesticides
because of uncontrolled weed populations. Choice (c) is incorrect because it describes crop rotation, not
no-tillage agriculture. Choice (d) is incorrect because it describes crop selection.
4.
(d); Choice (d) is correct. Natural fertilizers are generally more beneficial to soil structure than synthetic
fertilizers are. Choice (a) is incorrect. Natural fertilizers release nutrients more slowly than synthetic
fertilizers do. Choice (b) is incorrect because natural fertilizers have lower concentrations of nutrients than
synthetic fertilizers do. Choice (c) is also incorrect. Humans have used natural fertilizers for thousands of
years.
5.
False. Humans are greatly involved in engineered ecosystems. Most humans spend little time in natural
ecosystems. A true version of the statement would be: Humans use engineered ecosystems more intensively
than natural ecosystems.
6.
True. Integrated pest management uses a variety of methods to create efficient farms and minimize damage
to the environment.
7.
engineered; Farms, golf courses, and urban centres are constructed by humans. Therefore, they are
engineered ecosystems. Engineered ecosystems are different from natural ecosystems, which exist without
the influence of humans.
8.
monoculture; Monoculture is a system of agriculture in which large fields grow only one species.
Monocultures are part of agroecosystems, or farm ecosystems.
9.
leaching; Leaching occurs when nutrients dissolve in water and seep out of the soil.
10.
organic farming; Organic farmers rely on only non-synthetic pesticides and fertilizers. This is different
from integrated pest management, which allows a limited use of synthetic pesticides and fertilizers.
11. (a)(iii)
Farmers change, or alter, the time when they plant and harvest crops to avoid periods when pest
populations are at their peak; (b)(i) Farmers use certain species, such as wasps, to prey on or infect pests;
(c)(ii) Farmers plant crops in a different place each year so that pest populations cannot establish in one
area; (d)(iv) Farmers use pheromones to lure and confuse pests during the mating season.
12.
Sample answer: They can promote public transportation and support efforts to shop locally.
13.
Without air spaces in the soil, water and oxygen cannot penetrate the soil to reach plant roots.
14.
The food web in a monoculture is much less complex, with only one producer and possibly pest species.
15. (a)
Sample answer: Yes. Natural fertilizers are usually less concentrated than synthetic fertilizers, and they
can have less of a negative impact on the soil. Natural fertilizers may even improve soil structure.
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(b)
16.
Without fertilizers, the soil on farms would lose nutrients. As a result, the farms would produce
less food.
Sample answer:
Advantages
Disadvantages
• reduce damage to crops from pests
• control populations of organisms that spread diseases
• increase crop yield
• harm non-target species
• lead to bioamplification in the food chain
• become sources of soil, air, and water pollution
17. (a)
(b)
Sample answer: A forest, a stream, and a lake are three natural ecosystems in my area. Maple trees
and deer are native species in the forest ecosystem. Crayfish and salamanders are native to the stream
ecosystem. Frogs and smallmouth bass are native to the lake ecosystem.
Sample answer: A shopping mall, a playground, and a backyard are engineered ecosystems. The paved
area around a shopping mall replaced grass and other plants. The wood chips and concrete on a
playground cover the soil and prevent plant growth. A backyard usually includes trimmed grass and
non-native plant species.
18.
A natural forest is more sustainable. Its higher biodiversity allows many species to interact and maintain
natural cycles. A farm cannot sustain itself. It needs a farmer to manage input and output.
19.
Leached nutrients from fertilizers may be affecting the pond. These nutrients increase the growth of algae,
which then die and decompose. The process of decomposition uses up oxygen so that the trout do not
have enough oxygen to survive.
20. (a)
(b)
Sample answer: By spending time in natural ecosystems, people may appreciate the natural world
more. They may try to use fewer resources and have a smaller impact on the environment.
Sample answer: I could invite them to go on a hike or a picnic with me. I could show them beautiful
pictures of nearby parks and other natural settings.
21.
Farmers would not need to spend as much time or money to create ideal conditions for their crops. For
example, farmers in dry areas might not need to spend as much on large-scale irrigation systems. At the
same time, crop selection reduces the impact of farming on the soil ecosystem.
22.
Sample answer: My city offers a bus service to reduce the number of cars on the road. It also provides
recycling bins around the city to promote recycling.
23. (a)
(b)
24.
The term pest is applied to organisms that are detrimental or undesirable from a human perspective.
All species behave in a certain way to survive, not to bother other species.
Sample answer: I think many forest species, such as deer and owls, would consider humans to be pests.
Humans compete with them for resources and space. Deforestation by humans takes away their habitats.
Sample answer:
Dear Manager,
I think you should consider selling organic products in your store. Many customers are aware of the
negative effects that agriculture has on the environment. They would prefer to buy the products of
organic farming, even if they cost slightly more. By offering more choices, you will draw more customers
to your store.
Sincerely,
John
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25.
Sample answer:
Engineered
ecosystems
Natural
ecosystems
high biodiversity
stable biogeochemical
cycles
many producer species
many consumer species
many predator species
no human tending
plants
animals
other
organisms
water
air
soil
rocks
low biodiversity
disrupted biogeochemical cycles
few producer species
monoculture
few consumer species
few predator species
tended by humans
26.
A farmer would choose to use a synthetic fertilizer versus a natural fertilizer because the nutrients are
typically released at a faster rate and the amounts of nutrients released can be measured precisely therefore
eliminating the possibility of over- or under- fertilization. In addition, synthetic fertilizers are generally
easier to apply than natural fertilizers.
27.
The three main chemical soil nutrients are nitrogen, phosphorous and potassium.
28.
Bioaccumulation is the concentration of a substance, such as a pesticide, in the body of an organism. For
example, the concentration of DDT in a Lake Trout was found to be 1.08 ppm. Bioamplification is the
phenomenon where concentrations of toxins stored in the fats and oils or organism increase the higher up
the food chain because they are passed on to the organisms at the next trophic level. As an example, the
concentration of DDT in a Lake Trout (which is at a high trophic level in the food chain) was found to be
1.08 ppm which is much greater than the DDT concentration found in a Freshwater Shrimp (0.03 ppm)
which is at a lower trophic level in the food chain.
29. (a)
(b)
30. (a)
(b)
Sample answer: A community could improve its public transit system, ban the cosmetic use of
pesticides, and provide more green spaces within urban centres to reduce its ecological footprint.
Sample answer: Improving a communities, public transit system would reduce air pollution and energy
costs making it a more sustainable community. Banning the cosmetic use of pesticides would reduce
air and water pollution and energy use in the community. As well, it would decrease the health risks
associated with these chemicals. Providing more green spaces would improve air quality and encourage
healthier activities.
Air spaces in soil allow water and nutrients to pass through in order to reach plant roots. As well, they
provide oxygen to plant roots and soil organisms.
When soil is compacted air spaces are reduced. In turn, plant roots may not obtain enough oxygen,
water or nutrients to survive. As well, living organisms cannot access enough oxygen to survive.
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