You have seen that Earth's terrestrial biomes reflect regional variations in climate. But what determines these climatic variations? Interpret the following diagrams in reference to how each represents effects on global patterns of temperature, rainfall, and winds.

a. Solar radiation and latitude

b. Earth's orbit around the sun

c. Global patterns of air circulation and rainfall

Changes in the seasons are caused by

a. The tilt of Earth's axis toward or away from the sun

b. Annual cycles of temperature and rainfall

c. Variation in the distance between Earth and the sun

d. An annual cycle in the sun's energy output

What makes the Gobi Desert of Asia a desert?

a. The growing season there is very short

b. It is hot

c. Temperatures vary little from summer to winter

d. It is dry

Which of the following sea creatures might be described as a pelagic animal of the aphotic zone?

a. A coral reef fish

b. An intertidal snail

c. A deep-sea squid

d. A harbor seal

Why do the tropics and the windward side of mountains receive more rainfall than areas around latitudes 30° north and south and the leeward side of mountains?

a. Rising warm, moist air cools and drops its moisture as rain.

b. Descending air condenses, creating clouds and rain.

c. There is more solar radiation in the tropics and on the windward side of mountains.

d. Earth's rotation creates seasonal differences in rainfall.

Phytoplankton are the major photosynthesizers in

a. The benthic realm of the ocean

b. The ocean photic zone

c. The intertidal zone

d. The aphotic zone of a lake

Use Figures 34.5C and 34.18 to predict how global warming (rapid increase in Earth's average temperature; see Module 7.14) might affect the water cycle.

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Aquatic biomes differ in levels of light, nutrients, oxygen, and water movement. These abiotic factors influence the productivity and diversity of freshwater ecosystems.

a. Productivity, roughly defined as photosynthetic output, is high in estuaries, coral reefs, and shallow ponds. Describe the abiotic factors that contribute to high productivity in these ecosystems.

b. How does extra input of nitrogen and phosphorus (for instance, by fertilizer runoff) affect the productivity of lakes and ponds? Is this nutrient input beneficial for the ecosystem? Explain.

In the climograph below, biomes are plotted by their range of annual mean temperature and annual mean precipitation. Identify the following biomes:

Arctic tundra

Coniferous forest

Desert, grassland

Temperate forest,

Tropical forest.

Explain why there are areas in which biomes overlap on this graph.

The North American pronghorn looks and acts like the antelopes of Africa. But the pronghorn is the only survivor of a family of mammals restricted to North America. Propose a hypothesis to explain how these widely separated animals came to be so much alike.

In 1954, workers at Michigan State University began spraying the elm trees on campus annually with DDT to kill disease-carrying bark beetles. In the spring of 1955, large numbers of dead robins were found on the campus. Observers thought perhaps the robins died after eating earthworms contaminated by DDT the previous spring. Suggest how scientists could have investigated the scientific validity of this idea.