Regents Examination in Living Environment: Questions on Standard 4, Biological Concepts, Key Idea 7 - Human Impact on the Environment

Key Idea 7—Human Impact on the Environment
Human decisions and activities have a profound impact on the physical and living environment.

Human impact on the environment is most often more dramatic than the impact of most other living things because humans have a greater
need for water
need for food
ability to adapt to change
ability to alter theenvironment

Which human activity would have the most direct impact on the oxygen–carbon dioxide cycle?
reducing the rate of ecological succession
decreasing the use of water
destroying large forest areas
enforcing laws that prevent the use of leaded gasoline

Fertilizers used to improve lawns and gardens may interfere with the equilibrium of an ecosystem because they
cause mutations in all plants
cannot be absorbed by roots
can be carried into local water supplies
cause atmospheric pollution

The tall wetland plant purple loosestrife was brought from Europe to the United States in the early 1800s as a garden plant. The plant’s growth is now so widespread across the United States that it is crowding out a number of native plants. This situation is an example of
the results of the use of pesticides
the recycling of nutrients
the flow of energy present in all ecosystems
an unintended effect of adding a species to an ecosystem

Choose one ecological problem from the list below.
Ecological Problems
Global warming
Destruction of the ozone shield
Loss of biodiversity

Discuss the ecological problem you chose. In your answer be sure to state:
the problem you selected and one human action that may have caused the problem [1]
one way in which the problem can negatively affect humans [1]
one positive action that could be taken to reduce the problem [1]

Base your answers to next 3 questions on the information below and on your knowledge of biology.

The planning board of a community held a public hearing in response to complaints by residents concerning a waste-recycling plant. The residents claimed that the waste-hauling trucks were polluting air, land, and water and that the garbage has brought an increase in rats, mice, and pathogenic bacteria to the area. The residents insisted that the waste-recycling plant be closed permanently.
Other residents recognized the health risks but felt that the benefits of waste recycling outweighed the health issues.

Identify two specific health problems that could result from living near the waste-recycling plant. [2]
Identify one specific contaminant that might be released into the environment from operation of the waste-recycling plant. [1]
State one ecological benefit of recycling wastes. [1]


Which organism is a near-extinct species?
Japanese beetle
dodo bird
blue whale
passenger pigeon

Which human activity has probably contributed most to the acidification of lakes in the Adirondack region?
passing environmental protection laws
establishing reforestation projects in lumbered areas
burning fossil fuels that produce air pollutants containing sulfur and nitrogen
using pesticides for the control of insects that feed on trees

Compared to a natural forest, the wheat field of a farmer lacks
heterotrophs
significant biodiversity
autotrophs
stored energy

Which factor is not considered by ecologists when they evaluate the impact of human activities on an ecosystem?
amount of energy released from the Sun
quality of the atmosphere
degree of biodiversity
location of power plants

A new type of fuel gives off excessive amounts of smoke. Before this type of fuel is widely used, an ecologist would most likely want to know
what effect the smoke will have on the environment
how much it will cost to produce the fuel
how long it will take to produce the fuel
if the fuel will be widely accepted by consumers

Which of the following is the most ecologically promising method of insect control?
interference with insect reproductive processes
stronger insecticides designed to kill higher percentages of insects
physical barriers to insect pests
draining marshes and other insect habitats

Which is an example of biological control of a pest species?
DDT was used to destroy the red mite.
Most of the predators of a deer population were destroyed by humans.
Gypsy moth larvae (tree defoliators) are destroyed by beetle predators that were cultured and released.
Drugs were used in the control of certain pathogenic bacteria.

To ensure environmental quality for the future, each individual should
acquire and apply knowledge of ecological principles
continue to take part in deforestation
use Earth’s finite resources
add and take away organisms from ecosystems

Ladybugs were introduced as predators into an agricultural area of the United States to reduce the number of aphids (pests that feed on grain crops). Describe the positive and negative effects of this method of pest control. Your response must include at least:
two advantages of this method of pest control [2]
two possible dangers of using this method of pest control [2]


Some people claim that certain carnivores should be destroyed because they kill beneficial animals. Explain why these carnivores should be protected. Your answer must include information concerning:
prey population growth [1]
extinction [1]
the importance of carnivores in an ecosystem [1]



Key Idea 7—Human Impact on the Environment: Answers and Explanations
 

4 The fact that humans have a greater ability to alter the environment means that human impact on the environment is often more dramatic than that of most other living things. In addition to our ability to make physical changes in the environment, humans have the unique ability to alter the environment chemically, introducing many materials that are not found in nature and that cannot be converted to useful products by nature.
Wrong Choices Explained:
(1), (2) On an individual basis, humans’ need for water and need for food are not significantly greater than those of other living things. However, the fact is that our large population places incredible demands on the environment to supply these basic resources. As a result, our tendency to destroy natural habitats to create additional water and agricultural resources is a significant factor affecting the natural world.
(3) On an individual basis, humans’ ability to adapt to change is not significantly greater than that of other living things. However, as a species, we have created artificial environments to protect ourselves from harsh environmental conditions. To the extent that these artificial environments are dependent on energy and other natural resources, their construction and maintenance have resulted in significant alterations of the natural world.
 

3 Destroying large forest areas is the human activity that would have the most direct impact on the oxygen-carbon cycle. Reducing the number of trees over a large area would decrease the forest’s ability to absorb carbon dioxide and water and convert them to atmospheric oxygen and glucose. The millions of leaves in a forest are capable of releasing many tons of oxygen gas to the atmosphere. The massive bodies of forest trees can likewise store tons of carbon in the form of complex carbohydrates such as cellulose.
Wrong Choices Explained:
(1) Reducing the rate of ecological succession is not the human activity that would have the most direct impact on the oxygen-carbon cycle. Ecological succession is a process by which one plant-animal community is replaced over time by other plant-animal communities until a stable climax community is established. Reducing its rate would only have the effect of prolonging each successive community longer than might otherwise be expected but would not directly alter the cycling of carbon and oxygen.
(2) Decreasing the use of water is not the human activity that would have the most direct impact on the oxygen-carbon cycle. Water is a precious resource in many parts of the world. Reducing water use so as to conserve it would represent a positive impact of human activity on the environment but would not directly alter the cycling of carbon and oxygen.
(4) Enforcing laws that prevent the use of leaded gasoline is not the human activity that would have the most direct impact on the oxygen-carbon cycle. Lead is a dangerous heavy metal pollutant released when leaded gasoline is burned. Enforcing laws that limit its use would represent a positive impact of human activity on the environment, but would not directly alter the cycling of carbon and oxygen.
 

3 Fertilizers used to improve lawns and gardens may interfere with the equilibrium of an ecosystem because they can be carried into local water supplies. Once dissolved fertilizers enter streams, ponds, wetlands, or lakes, they provide an abundant nutrient source for the growth of algae. As masses of algae die off in the water environment, their decomposition can rob the water of oxygen needed for the survival of fish and other water-dwelling populations, causing their elimination from the habitat. When these species disappear, other species that depend on them for food must migrate or starve. Because the changes caused by the entry of fertilizers into water environments are so significant, it can be said that ecosystem equilibrium is destroyed.
Wrong Choices Explained:
(1) It is not true that fertilizers cause mutations in all plants. Some compounds with chemical structures similar to that of fertilizers are known to stimulate rapid gene mutation in plant cells that may lead to the death of the plant. However, the class of chemical compounds known as fertilizers do not have this effect on all plants.
(2) It is not true that fertilizers cannot be absorbed by all plants. When dissolved in water, fertilizers can easily enter plants by being absorbed via simple diffusion into root hairs.
(4) It is not normally true that fertilizers cause atmospheric pollution. Most fertilizers are relatively stable chemical compounds that are solids at normal temperatures. For this reason fertilizers are not normally responsible for atmospheric pollution unless they are applied in a gaseous form (such as ammonia) or become airborne (when attached to dry soil particles).
 

4 The situation described in the question is an example of an unintended effect of adding a species to an ecosystem. Although purple loosestrife has adapted well to North American habitats, its rapid growth in wetland environments has stressed or eliminated populations of cattail, pickerelweed, and other native plant species. The introduction of nonnative purple loosestrife to the North American continent has had an unintended negative effect on these native species and on the balance of nature established over many centuries.
Wrong Choices Explained:
(1), (2), (3) The situation described in the question is not an example of the results of the use of pesticides, the recycling of nutrients, or the flow of energy present in all ecosystems. The introduction of a nonnative plant (a living thing) is not the same as the introduction of a chemical pesticide, the recycling of nutrients, or the flow of energy (nonliving things).

A three-part response is required that must include the following points:
One human activity that may have caused the ecological problem selected from the list [1]
One way the problem may negatively affect humans [1]
One positive action that could be taken to reduce the problem [1]

Note: No credit is awarded for discussing an ecological problem not on the list.

Acceptable responses include: [3]
Global warming is a worldwide ecological problem that may be caused by the release of carbon dioxide and other gases in automobile exhaust. [1] This problem may negatively affect humans if the warming conditions disrupt weather patterns and lead to droughts, floods, or other natural disasters. [1] One positive action that could be taken to help the problem would be to find an energy source for automobiles that would not release carbon dioxide into the atmosphere. [1]
An ecological problem affecting humans is destruction of the ozone layer, which is caused by the use of chemicals known as CFCs as propellants in aerosol sprays. [1] This is a problem for humans because the ozone layer protects us from ultraviolet radiation from the sun; without this protection we would have an increased chance of getting skin cancer. [1] A way to help solve this problem would be to ban the use of CFCs in aerosols. [1]
Loss of biodiversity is an ecological problem that negatively impacts humans. This problem is caused whenever humans destroy a natural habitat and convert it to other uses. [1] The overall health of our environment depends on the diversity of species that fill different roles in nature. When species diversity and environmental health are reduced, our health is threatened as well. [1] This problem can be reversed only if we use education to learn that protecting natural species is just as important as protecting our own. [1]

Two responses are required. Acceptable responses include:
Asthma
Respiratory infections
Allergic reactions
Cancer
Bacterial infections
Viral infections
Disease linked to a pathogen
Poisoning linked to toxic contamination of groundwater

One response is required. Acceptable responses include:
Particles in the air
Presence of viruses or bacteria on trucks
Chemicals in air or water
Carcinogens
Mold and fungus spores

One response is required. Acceptable responses include:
Conservation of natural resources
Protection of finite resources
Energy conservation
Reduction in pollution
Landfills last longer
Preservation of open space resources
 

3 The blue whale is near extinction because of uncontrolled hunting by humans.
Wrong Choices Explained:
(1) The Japanese beetle is a plant pest that was accidentally introduced into the United States. Its population is kept in check by the praying mantis, its predator.
(2) The dodo bird became extinct because of hunting by humans.
(4) The passenger pigeon became extinct in the 1900s due to hunting by humans.
 

3 Burning fossil fuels that produce air pollutants containing sulfur and nitrogen is the human activity that has probably contributed the most to the acidification of lakes in the Adirondack region. These pollutants combine with water in the atmosphere to form sulfuric and nitric acids. These acids then enter lakes in rainfall and runoff, adding to the acidic quality of the lake water and killing many susceptible species.
Wrong Choices Explained:
(1) Passing environmental protection laws is not an activity that results in the acidification of lakes. In fact, it is a positive human activity that can help to limit the production and release of such gases into the atmosphere.
(2) Establishing reforestation projects in lumbered areas is not an activity that results in the acidification of lakes. In fact, it is a positive human activity that can help to replace trees lost because of the acidification of soils by acid rain.
(4) Using pesticides for the control of insects that feed on trees is not an activity that results in the acidification of lakes. It is a negative human activity carried out to protect commercial crops from destruction and does not normally result in the production of sulfur and nitrogen gases.
 

2 Significant biodiversity is the factor lacking in a wheat field as compared to a natural forest. Biodiversity is a term relating to the variety of life forms in an environment. Natural environments, including forests, are typically made up of thousands of species that interact to provide a balanced, ecologically responsive community. By contrast, farm fields are often limited to a small number of different species, and predominantly a single species. Communities lacking in biodiversity are unstable and prone to collapse when environmental conditions change.
Wrong Choices Explained:
(1) Heterotrophs are not lacking in a farm field compared to a forest. Heterotrophs are found within a wheat field, although their number and variety are normally limited to those that use wheat or its by-products as food.
(3) Autotrophs are not lacking in a farm field compared to a forest. Wheat is a type of autotroph, as are the various weed species that may be interspersed among the wheat plants in the field.
(4) Stored energy is not lacking in a farm field compared to a forest. As the wheat grows in the field, it absorbs the Sun’s energy and stores it as the chemical bond energy of carbohydrates and other organic compounds.
 

1 The amount of energy released from the Sun is not normally considered by an ecologist when evaluating the impact of human activities on an ecosystem. The amount of solar energy emitted by the Sun is generally constant and out of our direct control. Because it is not a variable that can be directly affected by human activities, it is usually not a consideration in decisions of this kind.
Wrong Choices Explained:
(2) The quality of the atmosphere is often a factor considered by ecologists in evaluating the impact of human activities on an ecosystem. Many human activities introduce chemical contaminants into the atmosphere. These chemicals may have a negative impact on the health and survival of humans and other species.
(3) The degree of biodiversity is often a factor considered by ecologists in evaluating the impact of human activities on an ecosystem. Human activities often put pressure on natural species, eliminating those unable to migrate or adapt. As biodiversity in an area declines, so does environmental stability. This situation threatens the health and survival of humans and other species.
(4) The location of power plants is often a factor considered by ecologists in evaluating the impact of human activities on an ecosystem. Fossil fuel plants can pollute the atmosphere and consume valuable petroleum products. Nuclear plants can release radiation and heat into the environment. Hydroelectric, solar, wind, and geothermal plants can destroy natural habitats because of space considerations. Each of these consequences can affect the health and survival of humans and other species.
 

1 An ecologist would want to know what effect the smoke will have on the environment before a new type of fuel is widely used. By understanding this effect, the ecologist can make more informed judgments about whether the smoke will harm the environment and human health.
Wrong Choices Explained:
(2), (3), (4) An ecologist is less likely to want to know how much it will cost to produce the fuel, how long it will take to produce the fuel, and if the fuel will be widely accepted by consumers. Although these are important questions for the manufacturer, they do not provide critical information for the ecologist, whose main concern is the protection of environmental quality for humans and other organisms.
 

1 Interference with insect reproductive processes is known as biological control. It is the most promising method of controlling insects because it is the least ecologically damaging.
Wrong Choices Explained:
(2) The use of insecticides is a chemical control of insects. Insecticides kill both harmful and helpful insects. The chemicals accumulate in the bodies of birds, fish, and mammals and interfere with their normal life activities.
(3) It is impossible to set up physical barriers for insects because they are motile and are also carried from place to place by animals and humans.
(4) Draining marshes and other insect habitats has helped to control many insects such as mosquitoes. However, this method interferes with the life cycles of useful organisms living in the area.
 

3 Insecticides are chemical pest controls. Biological controls are other insect species that feed on or in some way prey on an insect pest species. The example given here is control of the gypsy moth larvae by a certain species of beetle.
Wrong Choices Explained:
(1) DDT is an insecticide and represents chemical control. DDT is no longer used because it destroyed the insect food of birds and other wildlife.
(2) Humans upset the balance of nature (the balance of natural communities) by killing off deer predators. The deer population then increased so dramatically that deer starved to death because there was not enough food to support them.
(4) The use of drugs to cure disease is an example of chemical control of pathogens.
 

1 Each individual should acquire and apply knowledge of ecological principles in order to ensure environmental quality for the future. By understanding how environmental principles operate, we can make more informed judgments about activities that may harm the environment and human health.
Wrong Choices Explained:
(2) If each individual were to continue to take part in deforestation, environmental quality would be degraded. Because forests are a natural part of the environment, eliminating them disturbs the balance of nature and can have significant negative consequences for environmental quality.
(3) If each individual were to use Earth’s finite resources, environmental quality would be threatened. As these resources are used up, fewer remain for future generations. In addition, processing these resources consumes energy, produces pollutants, and adds to the solid waste problem.
(4) If each individual were to add and take away organisms from ecosystems, environmental quality would be diminished. Each natural community has established itself based on the particular niches filled by each type of organism. Adding to or taking away from this community upsets the balance of nature and would likely cause negative consequences.

Write one or more paragraphs describing positive and negative effects of this method of pest control. Include the following points:
Two advantages of this method of pest control [2]
Chemicals are not added to the environment.
Biological controls are more specific than chemical controls.
Ladybugs are less likely to kill beneficial organisms.
Desirable garden plants are protected from aphid attacks.
Birds and other unintended victims of pesticide use are spared.
Human health is protected against the toxic effects of pesticides.
Two possible dangers of using this method of pest control [2]
The control insects may eat the food of other organisms.
The population of natural predators of the aphids may be eliminated or greatly reduced.
The control organism may become overpopulated.
The control organisms may themselves become pests.

Sample paragraph: The method of pest control described is known as “biological control.” This method of insect control has some distinct advantages over chemical controls: First, biological controls don’t release toxic chemicals into the air and water, a fact that helps to protect wildlife and humans from being unintended victims of chemical pesticides. Second, biological controls are usually specific, which means that beneficial insects such as ladybugs and preying mantises aren’t harmed. [2] There are also some things we should be careful of in the use of biological controls: First, we should know a lot about the control organism to be sure that it doesn’t crowd out our native beneficial organisms. Second, we should remember that the control organism could become a pest, too, if it gets too numerous in the environment. [2]

Write one or more paragraphs explaining why carnivores should be protected. Include the following points:
Information concerning prey population growth [1]
­If predators are destroyed, the prey population will increase.
­If unchecked by predation or disease, a natural population will tend to increase in number geometrically.
Information concerning extinction [1]
­If too many carnivores of a particular species are killed, the species may become extinct.
­Extinction is a definite possibility when any species has too few members alive to carry out effective breeding.
­Complete elimination of any species from its natural range can destabilize the ecosystem.
Information concerning the importance of carnivores in an environment [1]
­By feeding on herbivores, carnivores help keep certain species of plants from being eliminated because of overgrazing in a particular area.
­Without predators to limit its number, a prey population could exceed the capacity of its range, resulting in widespread starvation and death of the prey population.

Carnivorous animals are part of the natural scheme that promotes ecological equilibrium.
Sample paragraph: Carnivores are important in an ecosystem because by reducing the number of prey organisms, the food organisms of the prey are kept from being eliminated from the environment. [1] If the predators were destroyed, the prey population would increase [1], perhaps to the point of consuming so many of the plants that the prey feed on that these plants would become extinct. [1]