Like Earth, Mars has seasons—its Northern Hemisphere experiences winter when its Southern Hemisphere experiences summer. Which statement is the best explanation for seasonality on Mars?
a. Mars is tilted on its axis.
b. Mars has an elliptical orbit that brings it closer to the Sun in summer than in winter.
c. Mars has a circular orbit and maintains a constant distance from the Sun.
d. The Southern Hemisphere of Mars consistently receives direct solar radiation.

Which statement best describes the desert biome?

a. It is found wherever temperatures are high

b. It contains a larger amount of biomass per unit area than any other biome

c. Its dominant vegetation is adapted to conserve water

d. Most are located at the equator; e. It is not suitable for human habitation

Compare the distribution of the natural terrestrial biomes of eastern North America with the distribution of anthropogenic biomes.

Which of the following biomes has a structure made up primarily of the mineral deposits secreted by its dominant organisms

a. Coral reefs

b. Freshwater lakes

c. Rivers

d. Estuaries

e. Oceans

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

In an ecosystem, how is the flow of energy similar to that of matter, and how is it different?

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

Scientists predict that global climate change will cause a greater increase in average temperature at higher latitudes than in the tropics. This seems like good news since most of the world's biodiversity occurs in the tropics. However, recent data suggest that a smaller temperature change in the tropics will cause a larger physiological response in organisms there than the larger temperature change will in organisms in temperate areas. Based on what you have learned about thermal niches in this chapter, propose a hypothesis to explain this result.

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