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Ch. 18: Food Resources
Students should be able to:
 Name the three most important food crops and explain why having just three
plants species to provide almost half of the calories people consume is a
potential problem.
 Contrast industrialized agriculture with subsistence agriculture and describe
different kinds of subsistence agriculture.
 Describe the beneficial and harmful effects of domestication on crop plants
and livestock.
 Describe the benefits and problems associated with the green revolution.
 Explain the roles of hormones and antibiotics in industrialized agriculture.
 Identify the potential benefits and problems of genetic engineering.
Food
 since the human population is constantly growing, can we continue to provide
enough food for everyone in a sustainable manner?
o although there is currently enough food per person right now, many
people (~ 1 billion) are undernourished, malnourished, or both, while
people in developed countries are often overnourished
o when our food security (world grain stocks) is threatened, food prices
increase, causing the poor to be more at risk (don’t have money to buy
food or land to grow it) and political unrest to increase
 heat waves and droughts reduce grain yields
 more corn is being converted into ethanol
 increased meat consumption in countries such as China has caused a
surge in grain used to feed livestock rather than people
o getting food to the people who need it most is often a political battle (red
tape, dishonest government officials, etc.)
What are We Eating?
 330,000 species of plants  100 plants provide 90% of our food  15 of those
100 species provide the bulk of the 90%  3 species (rice, wheat, and corn)
provide about half of all the calories we consume
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o what if one of these crops is wiped out?
 about 80 important livestock species (cows, sheep, pigs, chickens, turkeys,
geese, ducks, goats, and water buffalo are the most eaten)
o important sources of protein
o expensive  inefficient converters of plant material
 about half of all the grains grown in developed countries goes to
feeding livestock
Types of Agriculture
Industrialized
(Developed)
Subsistence
(Developing)
relies on large inputs
of capital and E (fossil
fuels)
produce enough food
to feed your family,
with little left over to
sell or store
E used to produce/run
machinery, irrigate,
and produce
agrochemicals
input of E is from
humans and draft
animals, not fossil
fuels
produces high yields
(less land has to be
converted)
types include slashand-burn, nomadic
herding, and
intercropping
can cause soil
degradation and
pesticide resistance
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Challenges
 domestication causes a loss of genetic diversity  can negatively affect longterm survival of crops/livestock because they are less able to adapt to changing
environmental conditions
o bred for uniformity and maximum production  more susceptible to
disease and pests, less able to adapt
o local varieties (domesticated versions of species that represent
adaptations to specific places) are becoming extinct
 we can cross-breed local varieties with modern varieties to increase
genetic diversity and resistance
 *read excerpt from Animal, Vegetable, Miracle with pictures
 increasing crop yields
o research of plant nutrition and pests has resulted in better fertilizers and
pesticides
o the Green Revolution (1960s)  using modern cultivation methods (use of
commercial inorganic fertilizers, pesticides, and machinery) and highyielding varieties of certain staple crops to produce more food per acre of
cropland
 developed countries shared their seeds, supplies, and knowledge
with less developed countries in Asia and Latin America
 can help the economy of some developing countries, but in
some cases, makes them dependent
 serious environmental implications (soil degradation, more E
use, loss of traditional know-how)
 what about Africa?
o as we gain more people, we cannot dedicate more arable land … because
there isn’t any more
 water shortage is also a major issue  have to convert to waterefficient irrigation
 law of diminishing returns  GMOs?
 increasing livestock yields
o hormones to promote faster growth
 some concern that these can promote cancer or affect growth of
children (although typically the amounts found in meat are quite
low)
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 EU bans meat from U.S. and Canada  health or economics?
o antibiotics (40% of all produced in the U.S.) are routinely added to animal
feed, even for healthy animals
 increased bacterial resistance to antibiotics (TB, MRSA, etc.) 
reduces medical effectiveness in humans
 many European countries have stopped at the urging of the WHO
o * show The Meatrix and discuss
 the gene revolution (making genetically modified foods/Frankenfoods)
o can alter traits of crops and livestock quicker than by using traditional
breeding methods
 can produce food that is more nutritious, resistant to disease, able to
grow in a variety of environmental conditions, grows faster
o regulated by the FDA in the U.S.
 seem to be safe, although there is some concern that introducing
GM crops might spread foreign genes into non-GM plants (like
weeds)
 food allergies are potentially possible
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