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Declining death rates due to increased food production and improved medical care while birth rates remain high is characteristic of the _______ stage.
transitional
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Canada's age-structure diagram _______.
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Many demographers believe that birth rates generally decrease as the level of development increases because
women tend to have more influence in family planning.
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Which of the following statements is false?
Only a few countries annually accept a large number of immigrants or refugees.
Increased food supplies and medical care have increased life expectancy.
The rise in the size of the human population is due primarily to a higher birth rate.
Women with access to education and jobs usually have fewer children.
Migration within countries plays an important role in the population dynamics of cities, towns, and rural areas.
The rise in the size of the human population is due primarily to a higher birth rate.
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Which of the following statements reflects the views of many of the world's leading scientists and analysts?
All parts of the world are well below carrying capacity for humans.
Parts of the world are exceeding carrying capacity for humans, and with current trends, eventually other parts of the world will, too.
Parts of the world are exceeding carrying capacity for humans, although most parts do not need to be concerned.
All parts of the world are currently exceeding carrying capacity for humans.
Parts of the world are exceeding carrying capacity for humans, and with current trends, eventually other parts of the world will, too.
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The Conservation Reserve Program pays farmers to _______.
stop cultivating highly erodible cropland
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Contour farming involves
plowing at right angles to slopes.
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What is the basis of the statement that we could feed more people if we would eat grain rather than feeding it to livestock?
the Second Law of Thermodynamics
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The critical organic component of soil that gives it its structure is termed
humus
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The parent material layer of a soil is composed of weathered
rock fragments.
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The major goal of range management is
maximizing livestock productivity without overgrazing.
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Which of the following are not part of integrated pest management?
subsidies for pesticide use
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The three crops that humans rely on for the majority of nutrients and calories are
wheat, rice, and corn.
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Fifty years ago, there were several hundred varieties of wheat grown in the Middle East. Now a few of the more modern high responder varieties have replaced the indigenous species. What are the implications of this change?
Genetic resources are diminished and an epidemic of wheat disease is likely due to the reliance on few species.
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Sustainable farming
is cheaper and safer than conventional farming.
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Among the most important characteristics of chemicals in determining their environmental risks is/are
toxicity
persistence
reactivity
All of these are correct.
solubility.
All of these are correct.
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The biomagnification of DDT demonstrates that
higher trophic level organisms can concentrate toxins in a type of "inverse biological pyramid."
-
Highly persistent toxic chemicals
retain their toxicity as they cycle through the food chain and environment.
-
An advantage of testing for toxicity by exposing animals to chemicals is that using animals is
a trusted and usually reliable way to get results.
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An LD50 is a dose of a toxic chemical that
Kills half the pupulation
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Which exposure route is the most common?
inhalation
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Two problems encountered in human health risk assessment are _______________________ and ___________________.
use of chemical mixtures; lack of knowledge about synergistic effects
lack of planning; the involvement of politics
lack of funding for federal mandates; lack of public support
There are no inherent problems in human health risk assessment.
extrapolation of data to low doses; extrapolation of data from non-human species to humans
extrapolation of data to low doses; extrapolation of data from non-human species to humans
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Calculate growth rate of population
(birth rate + immigration rate) − (death rate + emigration rate) = growth rate
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For a population with a growth rate of 2 per 1,000/year, how would you express that growth rate as a percentage?
.2%
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Which of the following are the major factors that determine a population's growth rate?
birth rate, death rate, emigration, immigration
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When a population approaches its carrying capacity, its resources ________.
become more scarce as population growth rate decreases
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________ describes the relative numbers of individuals from different ages within a population.
Age structure
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What describes the number of individuals in a population per unit area?
population density
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When a scientist looks at the __________ of a population, he or she is examining the proportion of males to females in the population.
sex ratio
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The carrying capacity is __________.
the maximum population size that a given environment can sustain.
-
Ignoring migration, the age structure of a human population likely to increase in size will have what shape?
pyramid
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Ignoring migration, the age structure of a human population likely to decrease in size will have what shape?
inverted pyramid
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Ignoring migration, the age structure diagram of a human population likely to maintain a relatively stable size will have what shape?
a rectangle tapering toward the top
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Sylva emphasizes the dangers to economies and social welfare systems from declining fertility rates. In comparison to Sylva, what would Seager say about declining fertility?
Declining fertility would provide many social benefits, such as less crowded schools and roads.
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Although Sylva and Seager seem to agree that couples should be able to make their own family planning decisions, they would disagree about which of the following statements?
Governments should provide resources and education for family planning.Submit
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1. A population with an annual growth rate of 3% doubles roughly every ___ years.
23
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A population that doubles in size every 14 years has a growth rate of ___ percent.
5
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How do you calculate exponentially growing populations?
Doubling time (in years) = 70 / annual growth rate (%)
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What is the Pre-Industrial Stage in the Demographic transition Model?
Populations grow slowly despite high birth rates because of high death rates
-
What is the Transitional Stage in the Demographic transition Model?
Large gap in birth and death rates leads to increase is population
-
What is the Industrial Stage in the Demographic transition Model?
Population slows as birth rates stop and approach death rates
-
What is the Post-Industrial Stage in the Demographic transition Model?
Populations stabilize when birth rates and death rates are low
-
-
Population increasing rapidly
-
-
Which of the following best describes human population growth from early times to the present day?
slow, uneven growth until the 1800s, then rapid growthSubmit
-
Which of the following statements about growth rate and population size is true?
When the growth rate decreases, population size will increase by greater increments with each successive generation.
If the growth rate remains steady, population size will continue to increase by greater increments with each generation.
When the growth rate increases steadily, population size decreases steadily.
Growth rate and population size are not related.Submit
If the growth rate remains steady, population size will continue to increase by greater increments with each generation.
-
__________ death rates and __________ infant mortality rates are due in large part to technological advances, improved sanitation, and better medical care in developed countries.
Lower; lower
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The natural rate of population change __________.
is the rate of population change due to births and deaths
-
Zero population growth occurs in a population when ________.
birth rate equals death rate and there is no migration
-
In the demographic transition model, a country's highest population growth rate is likely to occur during ________.
stage 2, the transitional stage
-
According to the demographic transition model of populations, over time __________.
rapid population growth is a short-term phenomenon between the drop in death rate and the drop in birth rate in a population
-
Which of the following statements about Earth's carrying capacity for humans is true?
Earth's carrying capacity for humans is approximately 350 million people.
Humans have a carrying capacity like all other species, although we can develop technology to help us overcome some of the limits that we would otherwise face.
Humans have a carrying capacity like all other species, although we can develop technology to help us overcome some of the limits that we would otherwise face.
Earth can support an infinite number of humans.Submit
Humans have a carrying capacity like all other species, although we can develop technology to help us overcome some of the limits that we would otherwise face.
-
Declining population growth rates in developing countries can be partially attributed to ________.
the education of women
-
The richest one-fifth of the world's population possesses approximately ________ times the income of the poorest one-fifth, and the richest one-fifth uses over 86% of the world's resources.
80
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________ has been shown to be the one of the greatest strategies for slowing population growth.
Family planning
-
Humus is ________.
the organic soil component that holds soil moisture and enhances soil fertility
-
Leaching and the rate of movement of water would be greatest in a soil classified as ________.
sand
-
Factors involved in soil formation include ________.
weathering of parent material and the addition of organic material
-
Leaching ________.
removes water-soluble nutrients from topsoilSubmit
-
The O horizon is ________.
primarily composed of organic materials
-
The breakdown of large rocks into smaller pieces is ________.
affected by rainfall, freezing, and thawing
-
Soil texture refers to the relative amounts of ________ in soil.
sand, silt, and clay
-
Which of the following is not one of the five main factors that influence weathering and the formation of organic matter?
climate
organisms
topography
soil horizons
soil horizons
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Which of the following horizons of soil would most likely contain the most minerals?
the B horizon
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________ is the loss of more than 10% of soil productivity in arid areas due to such factors as erosion, soil compaction, overgrazing, and forest removal.
Desertification
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Erosion can result in a positive feedback loop because ________.
plants are less likely to grow in eroded soil
-
Which of the following particles made up the dust that gave the Dustbowl its name?
suspended grains
-
Which of the following correctly shows the order for grains that would blow the least distance to grains that would blow the greatest distance?
rolling grains, bouncing grains, suspended grains
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Knight describes three “inescapable truths” about today’s West. He implies that _______.
the public ultimately benefits because ecologically rich private lands are kept open if ranchers can use public land for grazing
-
Monoculture farming ________.
is a development of industrial agriculture
-
The __________ introduced new technologies that increased crop yields dramatically and helped save millions of lives from starvation.
Green Revolution
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Demographers predict that global population will continue to increase. As population increases, which of the following statements represents future agricultural changes for maintaining an adequate food supply?
Higher food production per unit of agricultural landSubmit
-
On average, how far do agricultural products travel from farm to plate in the United States?
1400 milesSubmit
-
Today, it takes about ______ Calories of energy to produce about 1 Calorie of food.
55
-
It has been estimated that confined animal feeding operations contribute to about _____ of world carbon dioxide emissions.
15
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You are an international policy maker reviewing biotech crop regulations. Which of the following information sources would provide a reliable scientific assessment of the impacts of biotech crops?
A national scientific panel review of all the biotech crop research published over the past 15 years
-
What widespread farming practice is used to increase yield and profit?
planting monocultures
-
Why did the organic farmer sue the traditional farmer?
because the traditional farmer’s seeds contaminated his fields, causing him to lose his organic certification
-
As the global human population continues to rise, increased food production will most likely come from __________.
increased productivity of the land already used for agriculture
-
About 100 years ago, agricultural production in the United States tripled due to __________.
the invention of fertilizers and use of more modern machinerySubmit
-
For dinner, you have pasta with tomato sauce and meatballs, with cheese sprinkled on top. Which of these four is most likely to have been produced without bees?
cheese
meatballs
tomato sauce
pasta
Pasta
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The continued decline of bees in the United States is most likely due to __________.
many factors, including viral, bacterial, and fungal infections and improper use of pesticides
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Which of the following scenarios will most likely produce the most sustainable method of pollinating crops?
Surround an apple orchard with large fields of wheat.
Alternate fields of wheat and apple trees.
Include strips of wildflowers within and around an apple orchard.
In an apple orchard, only apply pesticides during the spring.
Include strips of wildflowers within and around an apple orchard.
-
Globally, approximately how many people are undernourished?
800 mil
-
Because of the Green Revolution, the average U.S. cornfield increased its yields by __________ during the 20th century.
fivefold
-
What was the impact of the Green Revolution on developing countries?
There were massive increases in production due to the use of crops better suited to advanced agriculture.
-
Cows require a high quantity of feed because they ________.
take time to grow and have a low energy conversion efficiency
-
What method of pest control operates on the principle that "the enemy of one's enemy is one's friend"?
biocontrol
-
Which of the following is a benefit of genetically modified food strains?
resistance to pests
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