The overgrowth of algae poses a major problem for coral reefs. Intensive fishing in one factor that contributes to algae overgrowth because it does which of the following?

A student sets up a compost bin outdoors. Inside the bin microorganisms convert the student’s vegetable and paper scraps into rich fertilizer. Which of the following best describes the role that these microorganisms play in natural habitats?

A native species and a non-native species are competing for resources within the same ecosystem. The non-native species is more likely to survive than the native species in which of the following situations?

Dead zones are low-oxygen areas that develop on the seafloor. Scientists hypothesize that phytoplankton blooms cause these dead zones. Phytoplankton blooms occur when excess nutrients are introduced by pollution from fertilizers, sewage plants, and the burning of fossil fuels. Which of the following would most likely cause an increase in these contributors to dead zones?

Some fungi secrete substances that are toxic to bacteria that compete with them for food. Scientists have used their knowledge of this ability of fungi in order to produce which of the following substances?

Hydrothermal vents form deep in the ocean when iron-rich magma is relased from openings on the seafloor. These vents spew extremely hot water (400°C) mixed with methane and sulfur. Bacteria that thrive in this hostile environment form the base of a food chain that leads to colonization by tube worms, mussels, and many other life-forms. When a hydrothermal vent becomes inactive and cold, the bacterial community that lives in the hot fluid methane and sulfur dies out. Which organisms most likely succeed the original community in this ecosystem?

Parrotfish are herbivores that are found in coral reefs. To escape predation, a parrotfish will graze with a rabbitfish, which has venomous spines at the end of its pelvic fins. The rabbitfish does not benefit from this relationship. Which type of relationship do the parrotfish and the rabbitfish have in the coral-reef environment?

As ecosystems move through the stages of succession, the populations of organisms in them change. Which of the following describes the stage of succession likely to have the most species diversity?

In recent years humans have interfered with the natural balance within deer populations in various ecosystems. The interference includes eliminating predators of the deer. Which of the following statements correctly describes the long-term outcome of this interference?

The food web shows the flow of energy through a sagebrush-steppe ecosystem. Which of these organisms are in a trophic level that receives a larger percentage of the energy captured by the producers than the percentage received at the bats’ trophic level?

A student is asked to draw a food web in which the same organism is a primary consumer as well as a secondary consumer. How should the organism be represented in the food web?

Bats eat insects that damage crops and mosquitoes that are vectors for disease. One million bats can eat several tons of insects per night, saving billions of dollars in pesticides yearly. Agricultural and public health scientists are concerned about the spread of white-nose syndrome (WNS). WNS is a result of a fungus that can infect cave-dwelling bats. While bats hibernate during winter months, the fungus covers the bats’ face and wings. WNS has a near 100% mortality rate, and 5.7 million bats have died since the discovery of the fungus in 2006. Many scientists are searching for ways to protect these bats. The relationship between this fungus and bats can best be defined as —

How do an increase in the organic matter in soil and an increase in soil depth affect the population of plants in an area?

In dry desert areas poor drainage can lead to a buildup of salt in water supplies. A student performed an investigation to study the effects of salinity on the germination rates of seeds. The student placed seeds in several solutions containing 0% to 3% salt. The length of the radicle, which is the root of the germinating seed, ranged from 49 mm in the 0% salt solution to 0 mm in the 3% salt solution. The data from this investigation suggest that increased salinity in more areas may lead to a decrease in which of the following?

During ecological succession, how does the growth of young hardwoods affect the organisms living in an ecosystem?

Which of the following is most likely to cause the greatest disruption to an ecosystem?

Which statement best describes the differences in species diversity between an ecosystem beginning the process of primary succession and one beginning the process of secondary succession?

Atmospheric nitrogen has to be combined with other elements, or fixed, in order to be used by plants. Lightning is one way that nitrogen is fixed. When lightning occurs, the extreme heat breaks the bonds in nitrogen molecules, allowing nitrogen to combine with oxygen and form nitrogen oxides. In what way is most of the nitrogen fixed by lightning made available for use by plants?

A student performed an investigation in which two ivy plants were planted in two separate containers. One of the containers had earthworms mixed in with the soil, and the other container had soil and no earthworms. The plants were given the same amount of water and exposed to the same amount of sunlight. The student observed that after several weeks of growth, the plant exposed to earthworms appeared to be healthier and exhibited more growth. To conclude that the relationship between the plant and the earthworm is an example of mutualism, the student must perform follow-up investigations that do which of the following?