ENVIRONMENTAL SCIENCECHAPTER 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.

Food Pyramid

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/gramSources: fruits, vegetables, bread, grains.

Function: primary source of energy (starch, glycogen). Only source of energy for the brainProtection (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. Must have nitrogen to make proteins (amino acids

contain nitrogen).4 cal/ gram20 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. Unsaturated Fat-not full of hydrogen; “crooked”.

Liquid at room temperature. Good for your heart.

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. 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. 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 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. 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.

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)