During the 19th century, sea otters were hunted almost to the point of extinction. When the number of sea otters became very low, it was noticed that the ecosystem of kelp bed “forests” was also disappearing. It was discovered that the sea otters were predators of sea urchins, which were, in turn, predators of the kelp. When sea otters declined, the sea urchin populations grew, destroying the kelp ecosystem and the many species that depended on it. It was then understood that sea otters were ________ in this ecosystem. *
True or false: Nearly all developed countries in the world are beginning a demographic transition in the 21st century. *
True
False
True or false: Human population growth has always been exponential. *
True
False
True or false: Most developed countries have passed through a demographic transition and currently have low population growth rates. *
True
False
True or false: A population can be clumped at one scale and uniform at another. *
True
False
Developed countries are characterized by *
A) industrial economies and low individual incomes.
B) agricultural economies and high individual incomes.
C) agricultural economies and low individual incomes.
D) industrial economies and high individual incomes.
True or false: The carrying capacity of a given geographic region for a single population can change over time. *
True
False
True or false: The human population may continue to increase even though it surpasses carrying capacity. *
True
False
Approximately 200 of the 300 native species of fish in Lake Victoria haven’t been observed since the 1960s and are therefore probably extinct. Using the estimate of the background extinction rate, how many species of Lake Victoria fish would one expect to have naturally become extinct during the last 50 years? *
A) less than 1
B) 1-10
C) 11-50
D) more than 50
Global climate change is likely to increase the rate of extinction worldwide. The pollutant most implicated in this problem is *
A) nitrous oxides.
B) carbon dioxide.
C) sulfur dioxides.
D) chlorofluorocarbons.
In order to be considered extinct, a species can’t be found *
A) at all, in the wild or in captivity at the present time.
B) at all, presently or during the past 10 years.
C) at all, presently or during the past 50 years.
D) in the wild presently but may exist in captivity.
Over the past 580 million years, biodiversity has *
A) smoothly and steadily increased.
B) smoothly and steadily increased until the past hundred years or so.
C) generally increased but with punctuations in the pattern.
D) rapidly increased until it started to rapidly decrease in the past hundred years or so.
The runoff of fertilizers from agricultural and residential areas can cause the aquatic algae in bodies of water to grow prolifically, resulting in a phenomenon called *
A) competitive exclusion.
B) habitat fragmentation.
C) eutrophication.
D) overexploitation.
The sudden loss of a ________ would necessarily cause the loss of most or all of a food web. *
A) producer
B) secondary consumer
C) mutualistic species
D) keystone species
Cattle egrets hitch a ride on domestic cows and eat insects that are stirred up by their activity. This is an example of *
A) commensalism.
B) competition.
C) predation.
D) parasitism.
Teosinte is a wild grass in Mexico from which corn (maize) was originally domesticated. Corn that is grown commercially is probably *
A) less genetically diverse than teosinte.
B) more genetically diverse than teosinte.
C) a threat to teosinte populations.
D) about as genetically diverse as teosinte.
During the 19th century, sea otters were hunted almost to the point of extinction. When the number of sea otters became very low, it was noticed that the ecosystem of kelp bed “forests” was also disappearing. It was discovered that the sea otters were predators of sea urchins, which were, in turn, predators of the kelp. When sea otters declined, the sea urchin populations grew, destroying the kelp ecosystem and the many species that depended on it. It was then understood that sea otters were ________ in this ecosystem. *
A) competitors
B) producers
C) a keystone species
D) parasites
Is a species that has few individuals at greater risk of extinction than a species with a large population size? Why or why not? *
A) Yes. A species with few individuals is more likely to be eliminated by a reduction in population size caused by a chance environmental event like bad weather or a fire.
B) Maybe. However, there’s no risk to a small population as long as genetic diversity is high.
C) Yes. A species with few individuals is likely to have a high percentage of heterozygotes. This can reduce the likelihood that the species can adaptively evolve in response to environmental changes.
D) No. Genetic drift allows small populations to avoid the loss of advantageous alleles from the population.
Earth’s axis is tilted away from the sun during ________ and toward the sun during ________ in the Northern Hemisphere. *
A) winter; summer
B) summer; winter
C) spring; fall
D) fall; spring
The temperature of a city is often warmer than the temperature in its surrounding suburbs. This is the result of an urban heat island effect. What is one reason why this effect occurs? *
A) The pavement and buildings absorb heat.
B) There are more parks in the city.
C) Fewer people drive in the suburbs.
D) Fewer buildings use air conditioning in the suburbs.
The dry deserts of Nevada are most influenced by *
A) the hot desert sun.
B) the Pacific Ocean.
C) overgrazing by livestock.
D) the rain shadow from a California mountain range.
France is at almost the same latitude as Nova Scotia. Why is France’s climate so much milder? *
A) France is surrounded by mountains that buffer it from all severe weather conditions.
B) Nova Scotia isn’t near a large body of water, but France is located adjacent to the ocean.
C) There are more people in France than Nova Scotia, thus human activity warms up the former region during colder periods of the year.
D) The Gulf Stream brings warm water from the tropical Atlantic to France, modifying its climate.
The amount of light received by a given unit area over time is called *
A) solar precipitation.
B) solar irradiance.
C) solar flare.
D) solar convergence.
Regions that have ________ levels of solar irradiance have ________ average temperatures. *
A) low; varying
B) high; low
C) low; low
D) high; varying
Hypothetically, scientists could lower Earth’s temperature by ________, in order to combat global warming. *
A) moving ice from the Arctic to the tropical oceans
B) forcibly melting more glaciers and polar ice caps
C) reflecting more light from land masses
D) decreasing the reflectance of cities
Treatment of wastewater in industrial plants of developed countries includes *
A) removing excess nutrients, such as phosphates and nitrates.
B) removing semisolid wastes.
C) discharging untreated wastewater into waterways.
D) burning semisolid wastes for energy.
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