When a population approaches its carrying capacity, its resources ________.

Where will you find epiphytes growing?

In a forest, the upper level of leaves and branches in the treetops is called the 

Read the following scenario and answer the question below. Human activities, including fossil fuel combustion, farming, and deforestation, are known to increase the levels of carbon dioxide, methane, and nitrous oxides in our atmosphere. Measurable warming of Earth due to these greenhouse gases can alter ecosystem dynamics. In addition to the direct climatic effects on organisms within biomes, warming can lower levels of sea ice and increase precipitation in Arctic areas. Global warming can also melt permafrost in the tundra and increase sea surface temperatures, which could increase the intensity of hurricanes in vulnerable areas. Within communities, climatic change can shift interdependent species “out of sync,” potentially causing indirect loss of species. For example, if pollinators and the plants they pollinate become out of synch, the pollinators may not be able to switch to a different food source, and the plants may not be able to reproduce. If the climate warms significantly, tundra permafrost may melt, which may lead to ________ the community.

The Cuyahoga River in Ohio had been so polluted that it caught fire repeatedly from 1868-1969, including a 1952 fire that resulted in nearly $1.5 million in damages. Amazingly, other rivers in the United States also caught fire during this period. Why didn’t federal laws limiting pollution of rivers and streams prevent this pollution and these fires?

________ involves meeting the needs of the present without sacrificing the ability of future generations to meet their own needs.

European rabbits were introduced into Australia and quickly spread, reproduced, and became a terrible pest. They eat up to $600 million worth of food and pasture crops annually, and have damaged the populations of many native plants and the populations of animals that eat the plants. Twice in the past 50 years, rabbit diseases have been introduced to try to control the population, with some success. This is a case where ________.

The ________ system of timber harvesting involves leaving small numbers of mature trees in place to provide shelter for seedlings as they grow.

Earthquakes result from ________.

Read the following scenario and answer the question below. Burning fossil fuels and their derivatives produces, among other things, harmful pollutants such as particulates, acid rain-producing sulfur and nitrogen oxides, and carbon oxides. These air pollutants threaten ecosystems all over the world, and high carbon dioxide levels contribute to global warming. Furthermore, fossils fuels have a limited supply. The market price of fossil fuels, especially crude oil, has continued to rise in recent years. Despite this, Americans continue to consume fossil fuels at alarming rates and rely upon them for most of energy needs. At various times, the federal government has considered mandating higher fuel efficiency standards for American vehicles as a possible solution to this environmental energy crisis. Most auto manufacturers, however, are opposed to the imposition of standards. What factor might lead to more political support for higher fuel-efficiency standards?