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New fuels are being produced by converting corn and grasses into compounds containing alcohols that can be broken down for energy in various engines. The purpose of this research is to
A. reduce the use of nonrenewable resources.
B. increase the rate of air pollution.
C. reduce the rate of homeostasis in organisms.
D. cause a loss of biodiversity in the rain forests.
A. reduce the use of nonrenewable resources.
The use of nonrenewable resources has negative effects for many ecosystems as well as human beings. New ways to use renewable resources for energy are now being developed.
The presence of wastes, such as plastic bags and motor oil, in lakes and streams miles away from developed areas suggests that
A. ecosystems are interconnected and human action can alter ecosystem equilibrium.
B. recycling programs have failed to conserve biotic resources.
C. natural processes can alter ecosystem stability.
D. direct harvesting practices have led to irreversible destruction of ecosystems.
A. ecosystems are interconnected and human action can alter ecosystem equilibrium.
Human impacts on the environment can be far-reaching. What we do in our own area of the Earth, can effect what happens in other areas as well.
The northern elephant seal was almost hunted to extinction in the 1800s. By the late 1890s, approximately one hundred seals were left, reducing the gene pool of the population. What will be the consequence of this reduction?
A. Competition within the population will increase.
B. The surviving elephant seals will be better able to adapt.
C. Inbreeding will be less frequent among the remaining population.
D. The elephant seals will be more vulnerable to environmental change.
D. The elephant seals will be more vulnerable to environmental change.
The more genetic variation a population has, the more easily the population can deal with environmental change. If the gene pool decreases, genetic variation decreases.
A community is concerned about the water quality of a nearby lake. Increased sedimentation in the lake is endangering the native habitat. The increased sedimentation is most likely caused by which of the following?
A. trees planted along the shore of the lake
B. construction of homes along the lake
C. the amount of sunlight on the lake
D. the amount of fish in the lake
B. construction of homes along the lake When homes are constructed, trees and plants are removed. Under natural conditions, trees and plants help to secure the soil and prevent erosion and sedimentation in lakes and rivers
A strip mining company wants to lease some land that is currently part of a national park. They promise to reclaim the land should any minerals be mined from the area, and they are willing to pay top dollar for the rights. As an ecologist, what factors would you raise with the local government?
A. the threat to local biodiversity
B. management of the land after the company leaves
C. the new jobs that would be created
D. the increased traffic in the area
A. the threat to local biodiversity
Any time land is modified from its original natural state, the local organisms will be affected
When fertilizers run off farmland into streams and ponds, the nitrogen content of the water increases. This can lead to rapid growth of algae in a process called eutrophication. How can this process affect other organisms in the water?
A. Oxygen is used up as algae is decomposed, reducing the amount available to other organisms.
B. The water becomes better able to support aerobic organisms.
C. The algae provide food for fishes and other organisms, leading to decreased algae populations.
D. The extra nitrogen provides additional food for the other organisms, increasing their population.
A. Oxygen is used up as algae is decomposed, reducing the amount available to other organisms.
Algal blooms, often caused by high levels of nitrogen in water lead to low dissolved oxygen levels and the death of many species in these ecosystems.
How does the predator-prey relationship affect a population?
A. The predators and prey are in competition with each other.
B. Usually either the predator or the prey will become extinct.
C. The predator species usually has exponential growth.
D. The relationship controls the population size of both species.
D. The relationship controls the population size of both species.
The predators keep the prey population under control and the size of the population of prey limits the amount of predators an ecosystem can support.
Data on the immigration and emigration of a fish species would be most helpful in determining which of the following?
A. biological magnification
B. interspecies competition
C. population of the species
D. predator-prey relationships
C. population of the species
Population size is determined by births, deaths, immigration and emigration.
When an environment has reached its carrying capacity for a certain population, which of the following is true?
A. Growth and immigration rate is equal to death and emigration rate.
B. Growth and immigration rate is greater than death and emigration rate.
C. Growth and immigration rate is less than death and emigration rate.
D. Growth rate is exponential.
A. Growth and immigration rate is equal to death and emigration rate.
Carrying capacity is the maximum population size of a species that can exist in a given environment given the resources.
The pH of the water in several lakes in Norway and Sweden had decreased to below 5.0 due to an increase in acid rain. Which of the following is most likely to happen in these lakes?
A. the decline of several fish populations.
B. an increase in numbers of fish
C. an increase in the amount of primary producers
D. increased predator-prey relationships
A. the decline of several fish populations
Fish are sensitive to changes in pH and would experience a decrease in numbers if a shift in the pH of the water occurred.
Which of the following is a limiting factor in a population of organisms.
A. reproductive replacement
B. life spans of the members
C. fluctuations in atmospheric temperature
D. availability of food
D. availability of food
The availability of food is a limiting factor in a population of organisms. If there is not enough food, some of the organisms will die and the population will decrease in number.
Which of the following are abiotic factors that shape ecosystems?
A. worms, plants and temperature
B. wind, precipitation, and soil type
C. niches, trees, and bacteria
D. sunlight, mushrooms, and wind
B. wind, precipitation, and soil type
Abiotic factors are those that are non-living.
Whaling was a very profitable profession until whale populations crashed. The global community came together to enact a ban on whaling. However, Japan and Norway have not agreed to stop whaling. Which of the following is the most likely consequence of their decision?
A. The whale populations are bouncing back very successfully and are unaffected by Japan and Norway continuing to whale.
B. The whale populations are not rebounding as quickly as they might if all of the countries agreed not to hunt whales.
C. The whale populations have mutated into new kinds of organisms.
D. The whales are getting better at avoiding capture.
B. The whale populations are not rebounding as quickly as they might if all of the countries agreed not to hunt whales.
All countries must work together to prevent major human impact on fragile ecosystems and populations of organisms.
The common brushtail possum is a marsupial native to Australia. This possum was introduced to New Zealand where it had no natural predators and had an abundant food supply. Which of these likely occurred a few years after the introduction of this possum to New Zealand?
A. The possums became extinct.
B. The possums developed shorter life spans.
C. The possum population grew to a larger size.
D. The possum population evolved into a different species.
C. The possum population grew to a larger size.
With no natural predators, the possum population was allowed to grow unchecked.
Why are there so few aquatic plants and phytoplankton that live at the bottom zones in the ocean?
A. The ocean floor contains many decomposers.
B. Most sunlight is absorbed before reaching these levels.
C. Water is a limiting factor.
D. The temperature in these zones is extremely low.
B. Most sunlight is absorbed before reaching these levels.
Plants and phytoplankton are primary producers that rely on the sun to carry out photosynthesis. The bottom zones of the ocean have little to no light.
Many insects, such as mosquitoes and dragonflies, spend their juvenile stage as aquatic larvae before becoming winged and airborne adults. Most years, these insects are extremely abundant in the Arctic tundra in summer. What might account for this?
A. Adult insects spend the long Arctic winter laying thousands of eggs under the ice of frozen ponds.
B. Many insects migrate long distances to take advantage of good breeding areas in the tundra.
C. Pools of water which make good breeding areas are plentiful in summer as the permafrost melts.
D. Summer rains in the Arctic tundra replenish breeding ponds that dried up during the winter.
C. Pools of water which make good breeding areas are plentiful in summer as the permafrost melts.
A population of rodents becomes stranded on a remote island. Eventually, the population reaches the island’s carrying capacity. At this point, the birth and death rates are
A. relatively equal.
B. crashing.
C. density dependent.
D. density independent.
A. relatively equal.
Which of the following describes how an abiotic factor can impact the population dynamics in an ecosystem?
A. A parasite that invades a host can reproduce and cause a decline in the host species population.
B. Organisms that compete for the same resources will keep each other from overpopulating.
C. Predators will prevent herbivores from depleting the plants and other resources in an ecosystem.
D. Seasonal variations in temperature can cause some of the individuals in a population to die.
D. Seasonal variations in temperature can cause some of the individuals in a population to die.
If a snake species were introduced to an ecosystem where it had no natural predators, what long-term effect do you predict the snakes would have on the population dynamics of the ecosystem?
A. They would breed with native snake species, resulting in an increase in biodiversity in the ecosystem.
B. They would compete with native snake species for resources, causing a decline in native snake populations and possibly extinction.
C. They would form mutualistic relationships with native snakes, since they would occupy the same niche in the ecosystem.
D. They would serve as a food source for predators of native snakes, causing an increase in native snake populations.
B. They would compete with native snake species for resources, causing a decline in native snake populations and possibly extinction.
The choices that humans make every day affect the environment. Sometimes, our lifestyles can harm the environment rather than protect it. Which of the following would be most helpful in protecting the environment and achieving sustainability?
A. Buying paper products made from harvested trees
B. Buying fewer mass produced products
C. Using natural gas as a fuel source instead of petroleum
D. Using solar power to generate electricity
D. Using solar power to generate electricity.
A. Methane gas would pollute the ocean environment as shoreline organisms begin to die and decay.
B. Alteration in ocean salt levels would cause loss of species and unbalanced populations in marine food webs.
C. Nonrenewable resources in the ocean environment would become depleted and upset the ecosystem's balance.
D. Increased levels of salts and minerals in the ocean would result in overpopulation of marine bivalves due to strengthened shells.
Answer B. Alteration in ocean salt levels would cause loss of species and unbalanced populations in marine food webs.
Any change in abiotic factors (such as salinity) will have effects on the organisms in an ecosystem
DDT and other pesticides used over 50 years ago are still affecting the environment today. Scientists have found these substances in recent glacier runoff. Glacier runoff occurs during the summer, when precipitation that has fallen on glaciers during the winter is released. Ice layers from existing glaciers have been analyzed. The results of this analysis show that the concentrations of DDT and other pesticides were highest about 10 years after the use of these substances was banned.
This information shows that
A. DDT and other pesticides cause glacier runoff during the summer.
B. it takes humans over 50 years to analyze a glacier.
C. precipitation helps to break down pesticides.
D. the decision of one human generation may have an impact on future generations.
D. the decision of one human generation may have an impact on future generations.
Rainbow trout need at least 6.0 mg/L of dissolved oxygen to survive. Biologists are trying to reestablish rainbow trout in a mountain stream but the stream only has 5.5 mg/L of dissolved oxygen. Which of the following would be the most useful to encourage the development of the rainbow trout population?
A. Create more bends in the stream to allow the water to slow down.
B. Cut down trees along the stream to allow more sunlight to warm the water.
C. Pull out aquatic plants growing in the stream to allow oxygen to accumulate.
D. Remove dams along the stream to allow the water to flow faster.
D. Remove dams along the stream to allow the water to flow faster.
Carbon Dioxide is important in our atmosphere because it is required for photosynthesis and traps some heat, keeping the Earth warm. However, human produced carbon dioxide is a problem because it
A. leads to higher global temperatures.
B. disrupts the natural cycling of other greenhouse gases.
C. add too much carbon dioxide to the oceans.
D. causes uncontrolled photosynthesis.
A. leads to higher global temperatures.
The number of pythons found throughout Everglades National Park has increased in recent years. These huge snakes are not native to Florida and are believed to have been released into the wild by pet owners. Wildlife biologists have initiated attempts to capture and remove these pythons. Which statement best explains the biologists' reasons for removing these pythons from the Everglades?
A. The pythons could upset the territorial boundaries of native organisms.
B. The pythons could adapt to overcome diseases common to native snakes.
C. The pythons could prey on native organisms and cause native population to decline.
D. The pythons could begin to interbreed with native snakes and produce a more successful species.
C. The pythons could prey on native organisms and cause native population to decline.
Introduced species often prey on native organisms declining their populations, sometimes to extinction.