Transcript Chapter 14: Feeding the World

Chapter 14: Feeding the World
ENVIRONMENTAL SCIENCE
CHAPTER 14 (PGS 214 – 229)
MRS. PAUL
Section 14.1: “Human Nutrition”
 Humans need energy for growth, movement and
repair.
 Get energy by eating food.
 Must also consume nutrients to maintain health.
 2 types of nutrients:
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1. Macronutrients
2. Micronutrients
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Macronutrients: provide energy for the body.
Measured in kilocalories (kcal) = Calories
 Number = how much energy food provides.
 Carbohydrates, proteins, and fats
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Micronutrients: provide small amounts of chemicals needed in
biochemical reactions.
Food Pyramid
Macronutrients- Carbohydrates
 Carbohydrates-compound made of carbon,
hydrogen, and oxygen in 1:2:1 ratio.
 2 main types:
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1. Sugars- small and simple; absorbed quickly; provide
immediate energy.
2. Starches- larger and complex; steady, long-lasting energy.
 4 cal/gram
 Sources: fruits, vegetables, bread, grains.
 Function: primary source of energy (starch,
glycogen). Only source of energy for the
brain
 Protection (chitin-exoskeleton).
 Structural elements (cell wall)
Cellulose helps move food along your
digestive tract (yay fiber!).
Carbohydrates
Macronutrients - Protein
 Protein- compound made of amino acids; provide
body with materials to make blood, muscle, etc;
provide energy; carry other structures; serve immune
function.
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Must have nitrogen to make proteins (amino acids contain
nitrogen).
 4 cal/ gram
 20 amino acids
 12 can be made by human body.
 8 are Essential Amino Acids- must be obtained from food.
Macronutrients - Protein
 Sources: food from animals (meats, eggs, dairy);
grains (wheat, rice, corn); legumes (peas, beans,
peanuts).
 Combine foods to get all 8 essential amino acids.
Macronutrients - Protein
 Functions:
 Form structural parts of cell.
 Carry other structures (hemoglobin)
 Protection from disease (antibodies)
 Speed up chemical reactions (enzymes)
 Chemical messengers (hormones)
 Control traffic in and out of cell (cell membrane)
Proteins
Macronutrients - Fats
 Lipid- 3 long chains of fatty acids; component of cell
membranes, protective function, energy storage
function.
 Solid lipids- fats (butter and lard)
 Liquid lipids – oils
 9 cal/ gram
Macronutrients - Fats
 Saturated vs. Unsaturated Fats
 Saturated Fat-maximum number of hydrogens in the chain;
can’t fit any more
Saturated fats are more solid at room temperature.
 Bad for your heart
 Hydrogenated-worst for your heart; unsaturated fats pumped full
of hydrogen.
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Unsaturated Fat-not full of hydrogen; “crooked”.
Liquid at room temperature.
 Good for your heart.
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 Sources: dairy, meat, avocado, nuts, eggs, etc.
Saturated and Unsaturated Fats
Lipids
Vitamins and Minerals
 Micronutrients; play role in reactions that release
energy.
 All can be obtained from plants.
 Vitamins: A, B, C, D, E, K

Some are water soluble (excess excreted in urine) while others
are fat soluble (extra is stored in fat-can have TOO MUCH).
 Minerals: calcium, zinc, magnesium, iron, etc.
 Also can have too much or not enough.
Vitamins and Minerals
 Malnutrition-lack of a specific type of nutrient in the
diet.

Can also result from inability to absorb or use a nutrient even
if you are eating enough of it.
Section 14.2: World Food Supply
 Our food supplies have increased.
 Why are so many starving?
 1. Food increase due to advances in agricultural practices and
crop plants.
 2. Food is traded and the price is driven by economic factors.
The Green Revolution
 Began in 1960s when new strains of wheat and rice
were developed.
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New varieties more responsive to fertilizers and irrigation,
better resistance to disease, faster growth, and can adapt to
variety of climates.
High crop yields.
 Use modern methods to harvest more efficiently.
 Resulted in more food without increasing the
amount of farmland.
 Problems:
 Developing nations not have enough water to maintain new
crops.
 Not have money for fertilizer or modern machinery or fuel to
run them.
Wheat
Cash Crops
 Cash Crop-crop grown for purpose of sale.
 Get higher prices by exporting than by selling to local people.
 Problem:
 Income from sale of cash crops used to buy weapons and
support political leaders that help the landowners.
Food from the Water
 Fish and other sea animals.
 Estimated that oceans can provide 100 million tons
of food per year.
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Reached this in 1989-we now exceed this limit and are starting
to see the effects.
Quantities of fish are beginning to drop.
 Alternative:
 Aquaculture-commercial production of fish in a controlled,
maintained environment.
 Produces 85% of mollusks (clams, oysters, etc) eaten in US.
Section 14.3: Modern Farming Techniques
 Agriculture used to involve a lot of labor (preparing
soil, planting seed, maintaining crops, harvesting,
etc).
 Middle of 20th century-began to use machines
powered by fossil fuels
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Called “Industrialized Agriculture”
Efficient and productive
Require large amount of energy, pesticides, fertilizers.
Often run by corporations (agribuisinesses).
 Use of pesticides
 Increase in resistant insects and other pests.
 1992-California white fly infestation
 DDT and decline in bald eagle population
 Monoculture
 Farms growing only the 1 or 2 crops that bring in the most
money.
 Crops genetically identical = more vulnerable to disease
 Soil depleted of minerals = soil loses ability to produce healthy
crop.
 New grains
 Not adapted to local conditions
 Looking to use local grains in many areas
 Ex: quinoa – grows better than wheat or rice in mountainous
areas, high in protein, can be made into flour, cereal, beverages
and livestock feed.
Quinoa
Section 14.4: Sustainable Agriculture
 Modern agriculture has resulted in: soil erosion,
deforestation, desertification, hunger, war, and
environmental damage.
 Sustainable agriculture-called regenerative farming;
based on crop rotation, reduced soil erosion, pest
management, and minimal use of soil additives.
Crop Rotation
 Crop Rotation- changing the type of crop grown in
an area on a regular cycle.
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Usually 1 to 6 years per cycle
 Prevent soil from becoming depleted of nutrients
(nitrogen).
 Avoid use of synthetic fertilizers.
 Cover Crop- nonfood plants grown between grown
seasons on land usually left empty.
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Restore nitrogen to the soil and help to reduce erosion
Reducing Erosion
 Erosion- process where soil is lost, transported, and
reformed.
 Caused by wind and flowing water.
 When topsoil removed, loss of nutrients can make
area useless for farming.
 Can be reduced by irrigation and soil management.
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Irrigation-watering of fields; use systems that deliver less
water, but directly to the roots reduces erosion.
Tilling-turning the soil so lower layers are brought to the
surface.
Destroys weeds and other pests, brings nutrients to the surface,
improves drainage, and aerates the soil.
 Wastes water, uses energy, can increase erosion.
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Irrigation
Tilling
Pest Management
 Integrated Pest Management (IPM)
 Reduce pesticide use by 90%
 Use natural predators to manage pests (ex: wasps,
ladybugs, viruses and bacteria, etc)