Chapter 14: Feeding the World

1. Chapter 14: Feeding the World Environmental Science Chapter 14 (Pgs 214 – 229)

2. 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: • 1. Macronutrients • 2. Micronutrients

3. Macronutrients: provide energy for the body. • Measured in kilocalories (kcal) = Calories • Number = how much energy food provides. • Carbohydrates, proteins, and fats • Micronutrients: provide small amounts of chemicals needed in biochemical reactions.

4. Food Pyramid

5. Macronutrients- Carbohydrates • Carbohydrates-compound made of carbon, hydrogen, and oxygen in 1:2:1 ratio. • 2 main types: • 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.

6. 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!).

7. Carbohydrates

8. 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. • 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.

9. 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.

10. 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)

11. Proteins

12. 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

13. 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. • Unsaturated Fat-not full of hydrogen; “crooked”. • Liquid at room temperature. • Good for your heart. • Sources: dairy, meat, avocado, nuts, eggs, etc.

14. Saturated and Unsaturated Fats

15. Lipids

16. 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.

17. 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.

18. 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.

19. The Green Revolution • Began in 1960s when new strains of wheat and rice were developed. • 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.

20. Problems: • Developing nations not have enough water to maintain new crops. • Not have money for fertilizer or modern machinery or fuel to run them.

21. Wheat

22. 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.

24. Food from the Water • Fish and other sea animals. • Estimated that oceans can provide 100 million tons of food per year. • 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.

26. 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 • Called “Industrialized Agriculture” • Efficient and productive • Require large amount of energy, pesticides, fertilizers. • Often run by corporations (agribuisinesses).

27. 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.

28. 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.

29. Quinoa

30. 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.

31. Crop Rotation • Crop Rotation- changing the type of crop grown in an area on a regular cycle. • 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. • Restore nitrogen to the soil and help to reduce erosion

33. 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. • 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.

34. Irrigation

35. Tilling

36. Pest Management Integrated Pest Management (IPM) Reduce pesticide use by 90% Use natural predators to manage pests (ex: wasps, ladybugs, viruses and bacteria, etc)