Presentation on theme: "ENVIRONMENTAL SCIENCE CHAPTER 14 (PGS 214 – 229) Chapter 14: Feeding the World."— Presentation transcript:
ENVIRONMENTAL SCIENCE CHAPTER 14 (PGS 214 – 229) Chapter 14: Feeding the World
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
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.
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.
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!).
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.
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)
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. Unsaturated Fat-not full of hydrogen; “crooked”. Liquid at room temperature. Good for your heart. Sources: dairy, meat, avocado, nuts, eggs, etc.
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. 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.
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. 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 20 th 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).
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.
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. 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
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.