Download Answers to Thinking About the Environment End of Chapter Questions:

Answers to Thinking About the Environment
End of Chapter Questions:
1. What age group in humans is usually most affected by undernutrition, malnutrition, and
famine? Why?
Ans: Infants, children, and the elderly are more susceptible to poverty and chronic hunger. In
addition to poor physical development and increased disease susceptibility, children who are
malnourished do not grow normally. Because malnutrition affects cognitive development,
malnourished children do not perform as well in school as children who are well fed.
2. Distinguish among carbohydrates, proteins, and lipids.
Ans: Carbohydrates, such as sugars and starches, are important primarily because they are
metabolized readily by the body in cellular respiration. Proteins are large, complex molecules
composed of repeating subunits called amino acids. Lipids are a diverse group of biological
molecules that includes fats and oils.
3. Why is population control the most fundamental solution to world food problems?
Ans: World food problems are many, as are their solutions. The ultimate solution to chronic
hunger is tied to achieving a stable population in each nation at a level that its environment can
support. We are not going to be able to indefinitely increase the amount of food produced
globally so we must control population growth globally.
4. How is poverty related to chronic hunger?
Ans: People who are chronically hungry lack access to the food they need to have healthy,
productive lives. Those people that live in poverty do not have the resources to secure adequate
food supplies.
5. Distinguish between shifting cultivation and slash-and-burn agriculture.
Ans: Shifting cultivation is a form of subsistence agriculture in which short periods of cultivation
are followed by longer periods of fallow (land left uncultivated) in which the land reverts to
forest. Slash-and-burn agriculture is one of several distinct types of shifting cultivation that
involves clearing small patches of tropical forest to plant crops. Because tropical soils lose their
productivity quickly when they are cultivated, farmers using slash-and-burn agriculture must
move from one area of forest to another every three years or so, so slash-and-burn agriculture is
land-intensive.
6. Distinguish between intercropping and polyculture.
Ans: Intercropping is a form of intensive subsistence agriculture that involves growing a variety
of plants simultaneously on the same field. Polyculture is a type of intercropping in which
several kinds of plants that mature at different times are planted together.
7. What are two environmental problems associated with industrialized agriculture?
Ans: Soil erosion causes a decline in soil fertility as well as downstream sediment pollution.
Agricultural chemicals such as pesticides and commercial inorganic fertilizers cause air, water,
and soil pollution. Land degradation is the natural or human-induced process that decreases the
future ability of the land to support crops or livestock. Many insects, weeds, and disease-causing
organisms have developed resistance to pesticides, forcing farmers to apply larger quantities.
8. What was the green revolution?
Ans: Using modern cultivation methods and the high-yielding varieties of certain staple crops to
produce more food per acre of cropland is known as the green revolution.
9. Describe the environmental problems associated with farming each of these areas:
tropical rain forests; hillsides; arid regions.
Ans: Farming in tropical rain forests leads to leaching of soil nutrients and quickly leads to
infertile soil. Hillsides are prone to soil erosion caused by intermittent floods or frequent
droughts (and therefore wind erosion when the ground cover is removed). Arid regions require
large inputs of water, some agricultural regions remove water from aquifers faster than it is
recharged by precipitation, lowering water tables.
10. Give at least three examples of ways that industrialized agriculture could be made more
sustainable.
Ans: Sustainable agriculture avoids the continual use of antibiotics, large quantities of chemical
pesticides, and high levels of commercial inorganic fertilizers. Industrialized agriculture could
adopt the breeding of disease-resistant crop plants and the maintenance of animal health to limit
the use of pesticides and antibiotics. Instead of using large quantities of chemical pesticides,
sustainable agriculture controls pests by enhancing natural predator-prey relationships. For
example, apple growers in Maryland monitor and encourage the presence of ladybird beetles in
their orchards because these insects feed voraciously on European red mites, a major pest of
apples. Crop selection helps control pests without heavy pesticide use. In parts of Oregon, apples
are grown without major pest problems, but insects often infest peaches, whereas in western
Colorado, apples have major pest problems but peaches do well. Therefore, apples would be the
preferred crop for sustainable agriculture in Oregon, as would peaches in Colorado.
11. Current research has not demonstrated conclusively that organic foods are healthier to eat
than foods grown by conventional agriculture. If that is the case, then what is the benefit of
organic farming? (Hint: Is organic agriculture better for the environment? If so, how?)
Ans: In growing recognition of the environmental problems associated with industrialized
agriculture, more and more mainstream farmers are trying some methods of sustainable
agriculture. These methods cause fewer environmental problems to the agricultural ecosystem, or
agroecosystem, than industrialized agriculture.
12. What point is the cartoonist trying to make?
Ans: The cartoonist makes the point that both environmental pollutants and overfishing were
depleting the world’s fish stocks. The most serious problem for marine fisheries is that many
marine species have been overharvested to the point that their numbers are severely depleted.
According to the FAO, 62% of the world's fish stocks are in urgent need of management action.
13. What is the problem with open management?
Ans: Many nations have extended their limits of jurisdiction to 320 km (200 mi) offshore which
removes many fisheries from international use. However, many countries have a policy of open
management, in which all fishing boats of that country are given unrestricted access to fishes in
national waters. Open management can therefore lead to overharvesting by each individual
nation.
14. Explain why aquaculture is more like agriculture than it is like traditional fishing.
Ans: Aquaculture is more closely related to agriculture on land than it is to the fishing industry.
To optimize the quality and productivity of their “crops,” aquaculture farmers control the diets,
breeding cycles, and environmental conditions of their ponds or enclosures. Aquaculturists try to
reduce pollutants that might harm the organisms they are growing, and they keep them safe from
potential predators.
15. How does a sustainable agricultural system resemble a natural ecosystem?
Ans: Sustainable agriculture is modeled after natural ecosystems, with their high biological
diversity, biodegradation of materials, and maintenance of soil fertility. To this end, sustainable
agriculture relies on beneficial biological processes and environmentally friendly chemicals that
disintegrate quickly and do not persist as residues in the environment. The sustainable farm
consists of field crops, trees that bear fruits and nuts, small herds of livestock, and even tracts of
forest.