Transcript Chp 14 RAD Guide Feeding the World

Sunday, April 10, 2016
Teenager food pyramid
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Sec 14.1- Human Nutrition
What is the difference between
macronutrients & micronutrients?

Macro: provide the body with energy
 Ex. protein, lipids (fats), carbohydrates
Micro: provide the body with small amounts
of chemicals needed in biochemical reactions
ex. vitamins
Which units do we use to measure energy
from macronutrients?
 Kilocalories

 1 kcal = amount of energy needed to raise 1 kg of H2O
by 1oC
 Kilocalories are known as Calories to consumers.
 1 kcal = 1 Calorie
 So… The number of Calories in a food indicates how
much energy the food provides.
3 major groups of macronutrients.
1.

Carbohydrates: C,H,O in a 1:2:1 ratio
a.
b.
Basic unit is the monosaccharide (single ring)
Sugars:
a.
c.
Starches:
a.
d.
Simple carbs that are absorbed by the body quickly
Complex carbs that provide the body with steadier, long
lasting energy
Carb Energy
a.
Most carbs provide the body with 4kcal per gram
Simple Sugars-quick
energy
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s
Complex Starcheslonger lasting energy
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
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d
Proteins

 Basic unit = amino acids
 4kcal per gram
Amino Acids

 20 different amino acids arrange in numerous ways
to make proteins.
 Protein structure and function depend on this
arrangement.

d
Where do we get our
Amino Acids

 The human body can make (20 )many of the amino
acids.
 The remaining amino acids (8) are obtained from
food.
 essential amino acids = amino acids that must be
obtained from food.
Fats
 Basic unit is the Lipid

 3 fatty acids attached to glycerol
 9kcal per gram
 -saturated fat-usually
solids at room temp;
Worse for your health
ex. butter/lard
-unsaturated fat-usually
liquids at room temp
ex. oils
Lipid Functions

 Phospholipid Bilayer of Your Cells
Lipid Functions

 Energy Storage
Micronutrients

 Vitamins & Minerals
 Do not provide energy directly
 Obtained from fruits, veggies, & breads
 Play key roles in biochemical reactions responsible for:
 releasing energy
 structural formation
Undernourishment-are not
meeting their energy needs

 Adult nutritional requirements
 2000-2800 kcal per day
 500 million people worldwide are nutritionally
deficient (if they receive less than 90% of their energy
needs)
 13 million people die of starvation each year
 Causes: stunted growth, low mental development
World Hunger

Malnutrition

 Lack of a specific type of nutrient
 Examples:
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Kwashiorkor (lack protein)
Scurvy (lack Vit. C)
Beri beri (lack Vit. B1)
Rickets (Lack Vit. D)
Goiter (Lack iodine)
World Food Supply

 Food supplies worldwide are increasing.
 More food available per person
 Why are so many people starving.
 Food increases are in countries that already produced
enough food
 Long drought, lack of money, and civil war/political
stability make it difficult for the neediest countries to
improve food production.
Food Production and Economics

1.
Green Revolution: 1960’s
•
•
•
•
•
Developments of new strains of wheat & rice
These crops had more response to fertilizers and
irrigation
Crops were resistant to disease, grew faster, survived in
a variety of climates
Modern farming methods and machinery increased
efficiency
Greater crop yields
• Increase gains, decreases price!!
Green Revolution (cont)

 Intended to help underfed nations feed themselves
 However, farmers in developing nations:
 do not have an adequate water supply to maintain the new
crops
 Do not have money to buy fertilizers
 Do not own modern machinery
 Side effect of Green Revolution:
 Huge crop yields in developed nations drive down prices,
resulting in poorer farmers receiving lower profit for their
crops.
Cash Crops

 crops grown for purpose of selling
 MAIN POINT  Poor farmers in developing nations
can’t sell crops to other poor people in their own
country
 These farmers choose crops that can be exported

d

d
Food from the Water

 Oceans can provide approximately 100 million
metric tons of food per year without damaging
marine biomes.
 Currently, over 90 million metric tons per year are
harvested
Aquaculture

 Aquaculture: commercially grown food in controlled
water environment
 Reduces the overfishing of oceans
 Produces over 21 million metric tons of food
 Fish, clams, oysters
Aquaculture
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d
Modern Farming Techniques.

 Historically, Preparing soil, planting seeds, and
maintaining crops were done by hand
 Industrialized Agriculture (mid-20th Century)
 Equipment powered by fossil fuels replaced humanpowered tools
Industrialized agriculture’s positive
impact on food production

 Able to feed 5 people in 1850 per farmer; now able to
feed 78 people after industrialized agriculture
Industrial agriculture’s negative
impact on environment?

 Requires a large amount of energy, pesticides, and
fertilizers
Pesticide Resistance

 Pesticides kill most pests, but a small portion of the
pest population is genetically resistant and will
survive.
 These resistant pests are able to reproduce, passing
on the gene that is resistant to pesticides.
 Result: more resistant individuals within the
population.
Revisiting Mendelian
Genetics
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 Homozygous Dominant: TT
 Heterozygous: Tt
 Homozygous Recessive: tt
What is monoculture farming? Does
this have a positive or negative impact
on environment?

 Grow 1 or 2 crops that get highest prices
 Problems:
 No genetic diversity
 Vulnerable to disease
 soil becomes depleted
of nutrients
Ex. cereal crops-deplete soil of phosphorus
-potatoes- take away phosphorus & calcium
-fertilizers are used to combat the problem but pesticide
resistance occurs & fertilizers can hurt the ground water
-can also lead to erosion; so less yield of crops occur
Modern Agriculture
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 Driven by economics and international trade
 Negative Results
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Soil erosion
Deforestation
Hunger
War
Desertification
3 main components of
Sustainable Agriculture
1.

Crop Rotation: changing your crops on a regular
cycle
a.
b.
Prevents soil from becoming depleted of nutrients
Prevents the need for nitrogen-based fertilizers
Nitrogen Fixing
Legumes

s
2. Erosion

 Wind and Flowing Water are main agents of erosion
 When topsoil is eroded, organic and mineral
nutrients are lost.
 This is bad news for farmers.
Reducing Erosion

 Cover Crops
 Non food crops planted between growing seasons.
 Drip irrigation
 Delivers small quantities of water directly to roots of
plants
 No drain off
 Reduce tillage
 Process of turning the soil so that lower layers are
brought to the surface.
 Excessive tillage causes erosion.
d
Drip Irrigation
vs
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Flood Irrigation
3. Pest Management
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 IPM: integrated pest management
 Alternative to pesticides
 Use natural predators to control pest populations
 Bats, lady bugs, wasps, viruses, bacteria
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d