Ecology Unit Test

Mullet are local estuarine fish that move in schools and feed on plankton and plant matter. Natural predators of the mullet include spotted sea trout, sharks, pelicans and dolphins. The graph shows how the number of mullet in an area has changed over time.

Based on the data, one student concludes that a new predator was introduced into the area during this time period. Which of the following is a likely alternate explanation for the change in the mullet population?

• mullet prey increased in the area

• mullet parasites decreased in the area

• the temperature of the area increased

• the amount of aquatic plants in the area decreased

Data on the immigration and emigration of a fish species would be most helpful in determining which of the following?

• biological magnification

• interspecies competition

• population of the species

• predator-prey relationships

When an environment has reached its carrying capacity for a certain population, which of the following is true?

• Growth and immigration rate is equal to death and emigration rate.

• Growth and immigration rate is greater than death and emigration rate.

• Growth and immigration rate is less than death and emigration rate

• Growth rate is exponential.

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?

• an increase in numbers of fish

• the decline of several fish populations

• an increase in the amount of primary producers

• increased predator-prey relationships

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?

• The pythons could upset the territorial boundaries of native organisms.

• The pythons could adapt to overcome diseases common to native snakes.

• The pythons could begin to interbreed with native snakes and produce a more successful species.

• The pythons could prey on native organisms and cause native population to decline.

Why are there so few aquatic plants and phytoplankton that live at the bottom zones in the ocean

• The ocean floor contains many decomposers

• Most sunlight is absorbed before reaching these levels.

• Water is a limiting factor.

• The temperature in these zones is extremely low.

Salt water is an abundant resource but unusable for irrigation and drinking. As demands on freshwater sources increase, the use of desalination processes to remove salt from ocean water is increasing. A concern of desalinating water is the large amounts of recovered salts that are returned to the ocean. Which of the following describes the most likely impact of desalination on the surrounding ocean environment?

• Methane gas would pollute the ocean environment as shoreline organisms begin to die and decay.

• Alteration in ocean salt levels would cause loss of species and unbalanced populations in marine food webs.

• Nonrenewable resources in the ocean environment would become depleted and upset the ecosystem's balance

• Increased levels of salts and minerals in the ocean would result in overpopulation of marine bivalves due to strengthened shells.

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

• reduce the use of nonrenewable resources

• increase the rate of air pollution

• reduce the rate of homeostasis in organisms.

• cause a loss of biodiversity in the rain forests

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.

• DDT and other pesticides cause glacier runoff during the summer.

• it takes humans over 50 years to analyze a glacier.

• precipitation helps to break down pesticides

• the decision of one human generation may have an impact on future generations.

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?

• Competition within the population will increase.

• The surviving elephant seals will be better able to adapt.

• Inbreeding will be less frequent among the remaining population

• The elephant seals will be more vulnerable to environmental change.