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Wednesday, April 19, 2023Wednesday, April 19, 2023
Macro: provide the body with energy
Micro: provide the body with small amounts of chemicals needed in biochemical reactions
What is the difference between macronutrients & micronutrients?
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.
Which units do we use to measure energy from macronutrients?
1. Carbohydrates: C,H,O in a 1:2:1 ratioa. Basic unit is the monosaccharide b. Sugars:
a. Simple carbs that are absorbed by the body quickly
c. Starches: a. Complex carbs that provide the body with
steadier, long lasting energy
d. Carb Energy a. Most carbs provide the body with 4kcal per gram
3 major groups of macronutrients.
Simple Sugars
s
Complex Starches
d
Basic unit = amino acids 4kcal per gram
Proteins
20 different amino acids arrange in numerous
ways to make proteins. Protein structure and function depend on this
arrangement.
Amino Acids
d
The human body can make many of the amino
acids.
The remaining amino acids are obtained from food. essential amino acids = amino acids that must
be obtained from food.
Where do we get our Amino Acids
Basic unit is the Lipid
fatty acids attached to glycerol 9kcal per gram
Fats
Phospholipid Bilayer of Your Cells
Lipid Functions
Energy Storage
Lipid Functions
Vitamins & Minerals
Do not provide energy directly Play key roles in biochemical reactions
responsible for: releasing energy structural formation
Micronutrients
Adult nutritional requirements
2000-2800 kcal per day 500 million people worldwide are nutritionally
deficient 13 million people die of starvation each year
Undernourishment
World Hunger
Lack of a specific type of nutrient Examples:
Kwashiorkor (lack protein) Scurvy (lack Vit. C) Beri beri (lack Vit. B1) Rickets (Lack Vit. D) Goiter (Lack iodine)
Malnutrition
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, civil war, political stability make it difficult for the neediest countries to improve food production.
World Food Supply
1. Green Revolution: 1960’s
• Developments of new strains of wheat & rice• More response to fertilizers and irrigation• Resistant to disease, grow faster, survive in
variety of climates• Modern farming methods and machinery
increased efficiency• Greater crop yields
• Increase gains, decreases price
Food Production and Economics
Intended to help underfed nations feed themselves
However, farmers in developing nations: do not 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.
Green Revolution (cont)
crops grown for purpose of selling 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
Cash Crops
d
d
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
Food from the Water
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
d
Aquaculture
Historically, Preparing soil, planting seeds, and maintaining crops were done by hand
Industrialized Agriculture (mid-20th Century) Equipment powered by fossil fuels replaced
human-powered tools
Modern Farming Techniques.
Able to feed 5 people in 1850 per farmer; now
able to feed 78 people after industrialized agriculture
Industrialized agriculture’s positive impact on food production
Requires a large amount of energy, pesticides,
and fertilizers
Industrial agriculture’s negative
impact on environment?
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.
Pesticide Resistance
Homozygous Dominant: TT Heterozygous: Tt Homozygous Recessive: tt
Revisiting Mendelian Genetics
Grow 1 or 2 crops that get highest prices Problems:
No genetic diversity Vulnerable to disease
soil becomes depleted of nutrients
What is monoculture farming? Does this have a positive or negative impact on environment?
Driven by economics and international trade Negative Results
Soil erosion Deforestation Hunger War Desertification
Modern Agriculture
1. Crop Rotation: changing your crops on a
regular cyclea. Prevents soil from becoming depleted of
nutrientsb. Prevents the need for nitrogen-based fertilizers
3 main components of Sustainable Agriculture
s
Nitrogen Fixing Legumes
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.
2. 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.
Reducing Erosion
d
Drip Irrigation vs
Flood Irrigation
IPM: integrated pest management
Alternative to pesticides Use natural predators to control pest
populations Bats, lady bugs, wasps, viruses, bacteria
3. Pest Management
d