Food and Agriculture ( Holt Environmental Science) – Flashcards

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question
How can farmland become desertified?
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!. domestic animals are allowed to overgraze the land 2. too many crops are grown on the land and the land gradually loses its fertility 3. As a result of erosion, there is no fertile soil left to grow plants.
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Define: arable land
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land where it is possible to grow crops
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Why is there not enough food for the human population?
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Food production is not increasing at the same rate as human population.
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Which agriculture products require the least amount of energy to produce?
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plant
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What is the benefit to the no-till method of farming?
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Seeds are planted among the roots of the previous crop. The remnants of the previous crops are left to slowly decay providing nutrients to the soil.
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How can we deal with the problem of seafood overharvesting?
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We can raise aquatic organisms for human consumption (aquaculture)
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DDT is a very effective pesticide. How is it detrimental to the environment?
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1. It does not break down quickly into harmless chemicals. 2. It concentrates in the bodies of animals high in the food chain (biomagnification). 3. It causes some birds to lay eggs so thin thay they break when the birds sit on them.
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What are essential amino acids? How many essential amino acids are there? Why do humans need them?
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Essential amino acids are the amino acids that humans must have in their diet. There are 8 of them. These are the amino acids that our bodies can not synthesize from other materials.
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What are some factors can lead to famine?
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1. the failure of food production to keep pace with population growth 2. distribution problems caused by political turmoil 3. crop failure brought on by sustained / long-term drought.
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The Green Revolution increased food production providing food for the Earth's increasing population. What is a negative effect of the Green Revolution?
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The use of persticides and fertilizer increase the risk of pollution.
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How can soil erosion by wind and water be reduced?
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Erosion can be reduced by incorporating strips of vegetation into plowed land.
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Where does water for crop irrigation usually come from?
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Rivers and groundwater
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What can happen to pest populations after long term exposure to pesticides?
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The pests can become resistant to pesticides via natural selection.
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What are persistent pesticides?
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Persistent pesticides become concentrated in organisms high on the food chain. These pesticides undergo biomagnification.
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List some livestock products.
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leather, wool, eggs, meat, manure
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How is teh Earth's available arable land being reduced?
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It is being reduced by fast -growing human populations, soil erosion, and desertification.
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When is erosion most likely to happen?
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It is most likely to happen when to soil is bare and exposed to wind and rain.
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List 3 modern agricultural methods.
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1. plowing with machines 2. irrigatin with drip systems applying chemical fertilizers
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What is integrated pest management system?
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Integrated pest management used both chemical and biological means to control pests (unwanted animals in farming).
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What are the major types of organic molecules that our bodies need from food? Name two ways our bodies use these substances.
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Carbohydrates supply energy; proteins supply the amino acids needed to help build and maintain the body; and lipids (fats and oils) help form membranes and hormones. Lipids may also be stored and used later for energy.
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Explain how pests develop a resistance to pesticides.
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If some members of a pest population happen to have a gene that allows them to survive contact with a pesticide, they are more likely to survive and reproduce. The pests that are killed by pesticides will leave no descendants. Over time, a larger percentage of the surviving pests will be those that are not harmed by the pesticide. The quicker the pests breed, the sooner the resistance is noticed.
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Explain how biological insect control kills only the target insects while chemical insecticides kill many different kinds of animals
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Biological insecticides include bacteria and reproductive-interfering agents that target the problem insects but do not harm other unintended species. Chemical insecticides can persist or build up and then harm other species which feed on the insects.
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People have been farming for at least 10,000 years. If erosion had been going on at the current rate for all that time, we would have reached bedrock long ago. Why has erosion become a serious problem only recently?
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For most of the 10,000 years, farmers did not leave bare soil exposed in huge fields. Small fields and gardens meant less runoff. Crop residue was returned to the fields. Farmers also widely practiced crop rotation, and they let the land recover by letting fields lie fallow every few seasons. Erosion has become a serious problem with the widespread use of modern, efficient machinery and farming practices.
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Explain why political problems, as well as agricultural yields, can also affect hunger.
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When there is a war between countries or within a country, transportation is disrupted. Without transportation, food may sit in storage rather than being distributed to the people who need it. Also, political struggles are power struggles, and members of one side often withhold food from members of the other side simply to gain an advantage in the power struggle.
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Name at least three examples of livestock and describe three or more functions that they provide. How does the role of livestock differ in developing and developed countries?
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Most common examples include cattle, sheep, goats, pigs, chickens, horses, donkeys, and mules; also ducks and geese. Livestock are raised for meat, leather, wool, milk, and eggs; these are the primary uses provided in developed countries. People in developing countries are much less likely to use livestock for meat. Livestock in developing countries (and sometimes in developed ones) are also raised to serve as draft animals, and to provide manure for fertilizer or to be used as a source of fuel. In Africa, Masai herders drink blood from cattle.
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Describe the goals of integrated pest management and discuss the various steps involved in the method.
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Integrated pest management (IPM) does not set out to eliminate pest populations completely, but rather to reduce them to a level that reduces their damage to crops. A management program is designed for each step of the process: assessing crop and pest ecology to determine actions, identifying and monitoring pests, preventing pests, and later controlling pests when necessary. IPM incorporates, as needed, farming methods, biological pest control, and chemical pest control.
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The approximate energy yield of carbohydrates is 4 Cal/gram; fats yield about 9 Cal/ gram, and proteins about 4 Cal/gram. Assume the following about the food that Brad and Jenny consumed for lunch: Brad—100 grams protein, 20 grams fat, 75 grams carbohydrates; Jenny—75 grams protein, 10 grams fats, 75 grams carbohydrates. How many Calories each did Brad and Jenny consume? What was the percentage of fat Calories in the meal for each person? (6)
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Brad consumed 880 Calories, 20% (180 Cal) of which were fats (also accept 20.45%). Jenny consumed 690 Calories, 13% (90 Cal) of which were fats.
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Some people feel that the green revolution is a wonderful example of twenty-first-century technology that benefits millions of people. Others believe that the problems caused by the green revolution outweigh its benefits. Explain the advantages and drawbacks of the green revolution, and then state your own opinion.
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Advantage: Crops have higher yields, so more people can be fed from the same amount of farmland. Disadvantage: High-yield crops require more pesticides, fertilizer, and farm machinery than traditional crops.
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Describe how genetic engineering is used in agriculture.
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Scientists use genetic engineering to transfer genes for desirable traits, such as pest resistance, into crop plants from other organisms. Its benefits continue to be debated.
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