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Base your answers to questions 1 on the information below and on your knowledge of biology.
Since 1980, the vulture population in India has declined from 40 million to 60 thousand due to poisoning by a pain reliever used in cattle. If only 1% of the cattle carcasses fed on by vultures are animals that have been treated with the drug, it can lead to a drastic decline in the vulture population. The grim picture is that over 10% of the carcasses have been found to contain this drug.
Vultures feed exclusively on the carcasses of dead animals. This helps to prevent the spread of diseases such as rabies and anthrax among wildlife, livestock, and humans. Without as many vultures present, other scavengers such as dogs have moved in and taken advantage of the newly available food. The abundance of these other scavengers has led to an increase in the number of cases of human rabies and an outbreak of tuberculosis, anthrax, and foot-and-mouth disease. These diseases are not spread to humans by vultures.
The best explanation for the increase in rabies, anthrax, and other diseases in humans is that the*
Which statement best describes bat populations in a stable ecosystem?*
Which statement is an example of the inter- dependence of organisms?*
Which statement best describes what is most likely to occur if an animal population grows larger than the carrying capacity of its environment?*
The graph below represents some changes in the number of individuals in a particular population in a stable ecosystem over a period of time.
Which statement best describes the trend shown in this graph?*
Rabbits produce large numbers of offspring during each reproductive season, yet the number of rabbits within a given population changes very little from year to year. The stability of the population size is most likely the result of*
Each female housefly can lay approximately 500 eggs in a lifetime. She does this in several batches of about 75 to 150 eggs. Within a day, larvae (maggots) hatch from the eggs. They live and feed on organic material, such as garbage and feces. Scientists have calculated that a pair of flies beginning reproduction in April could be the ancestors of 191,010,000,000,000,000,000 fl ies by August.
Which statement best explains why this does not happen?*
In order for an ecosystem to remain stable there must be*
One way humans can promote the survival of organisms in an ecosystem is to*
A fundamental concept of ecology is that living organisms*
Base your answers to questions 11 on the information below and on your knowledge of biology.
Research has shown that plants might chemically change their environment. The roots of certain plants release many chemicals. Some chemicals made by plants can kill nearby plants or discourage herbivores from eating them. Other plant chemicals kill plant pathogens such as bacteria and fungi.
State two ways that the release of these chemicals is beneficial to these plants. 
Base your answers to questions 12 on the information below and on your knowledge of biology.
Coral Reef Ecosystems
There are many ecological interactions that maintain the biodiversity present in coral reefs. In addition to coral, microscopic algae, seaweed, sea grasses, sponges and worms, and a variety of fish are among the organisms that live in reef ecosystems. Ocean currents often link different reef systems and move organisms from one reef area to another. This movement is a factor in repopulating a reef that has been damaged by environmental changes.
One environmental change involves an increased growth of seaweed. When the population of seaweed increases, the reef shifts from a coral-dominated ecosystem to a seaweed-dominated ecosystem. This change disrupts the relationships between the organisms that live there.
Studies have shown that, as the density of seaweed in a reef area increases, the number of fish that eat the seaweed in that area decreases. This may be due to the presence of more predators, or the taste of the more mature plants. The fish move to areas where there is less seaweed growth. As this trend continues, the reef areas are taken over by the seaweed. Once this happens, it is very hard to remove the seaweed and restore the reef to a healthy ecosystem.
In addition to this problem, temperature changes are threatening the ocean currents that connect the reef systems. A change in the currents would reduce the movement of fish larvae from one area to another. This contributes to the seaweed problem.
State one reason why it is important to maintain the stability of the coral reefs. *
Base your answers to question 13-14 on the information below and on your knowledge of biology.
Survey Finds Invasive Snail in St. Lawrence River That Could Threaten Waterfowl
New research has found a larger presence of faucet snails in the Great Lakes than previously recognized, including the northern parts of Lake Ontario and the St. Lawrence River. The invasive species can carry three types of intestinal parasites that can injure and kill waterfowl such as ducks. ...
...When the waterfowl eat the snails, the parasites attack internal organs, causing lesions [sores] and hemorrhage [uncontrolled bleeding]. Birds affected by the snail will fly and dive erratically before their eventual death. The university said that the snails are about 12 to 15 millimeters in height at full size, brown to black with a distinctive whorl of concentric circles on the shell opening cover that looks like tree rings. ...
...Mr. Kosnicki [an ecologist] said the spread of snails, along with other invasive species, shows the need for increased awareness of possible contaminants coming from boats and in runoff from land. ...
Source: Watertown Daily Times, Monday, January 19, 2015, by Gordon Block
Discuss how invasive species can harm an ecosystem. In your answer, be sure to:
• explain one negative effect that faucet snails have on the lake ecosystem 
• describe one human activity that can slow the spread of the faucet snail *
Base your answers to questions 15 on the passage below and on your knowledge of biology.
Indian Ocean Ecosystem in Danger
The Indian Ocean is under increasing environmental pressures. Until recently, this ocean was considered to have the least ecologically disrupted coastline. However, as the surface water temperatures have increased, there has been a reduction in the phytoplankton population (microscopic producers). This reduction in phytoplankton has been linked to a decline in some fish populations.
Also affecting the fish populations is the urbanization of coastal areas. As the human population grows in this area, more of the coastline region is being developed. In addition, the mining of natural resources has led to oil spills, the destruction of mangrove forests, and an increase in the area’s acidity level.
Countries along the coast are trying to encourage development while, at the same time, trying to maintain a healthy coastal ecosystem.
Explain how a reduction in phytoplankton can lead to a reduction in fish populations in the Indian Ocean. *
Base your answers to questions 16 on the diagrams below and on your knowledge of biology. The diagrams represent how various populations interact in a forest environment.
State what would most likely happen to one other population in this food web if all the squirrels and rabbits were suddenly killed by a viral disease. Support your answer. *