A lake affected by high levels of artificial eutrophication will have:

a. high nutrient levels, large phytoplankton populations, and low oxygen levels at depth.

b. high level, nutrients, low phytoplankton levels, and high oxygen levels in surface waters.

c. low nutrient levels, large phytoplankton populations, and low oxygen levels at depth.

d. low nutrient levels, low phytoplankton populations, and high oxygen levels at depth.

e. low nutrient levels, large zooplankton populations, and low phytoplankton levels.

An ecosystem includes a ________ of organisms and the _______ with which they interact.

The carbon that helps make up the living world moves into it by means of organisms that perform _______. Carbon then returns to the soil and atmosphere through means of the _______of organic material by the organisms called _______ and _______.

Almost all the nitrogen that enters the living world by natural means does so through the actions of _______. Nitrogen is then returned to the atmosphere by the actions of _______.

All the organisms at the first trophic level perform _______ and thus are referred to as _______. Any organism that feeds solely on first-trophic-level organisms would have to be a (choose one) carnivore/herbivore/omnivore.

All material produced by living things is capable of being broken down into its inorganic components by the class of living things called _______. This material is thus said to be _______.

There are fewer predator than prey animals due to drastic reductions of _______ at each _______.

Ozone is a gas composed entirely of the element _______ that reaches its greatest density in the layer of the atmosphere known as the _______ and that has the effect of keeping _______ from reaching Earth’s surface.

Most of the energetic short-wave radiation from the sun is transformed into _______, which can be trapped by greenhouse gases such as _______ and ________.

Global warming is certain to produce a _____ in global sea levels and a(n) _______ in precipitation in the United States.

The warm surface air of the tropics _______ as it rises, causing it to _______ moisture. At about 30° N and 30° S of the tropics, however, air descends and _______ moisture from the land.