31) About 99 percent of the UV radiation that the sun showers on Earth is blocked by:

A) stratospheric ozone.

B) stratospheric greenhouse gases, such as CO2 and water.

C) the magnetic fields that surround the Earth.

D) tropospheric greenhouse gases, such as CO2 and water.

E) ground level ozone.

32) The “ozone hole” is caused by the:

A) buildup of toxic ozone in the troposphere over cities such as Los Angeles from human-caused pollution.

B) depletion of ozone in the troposphere by chemicals such as CFCs.

C) depletion of ozone in the stratosphere by chemicals such as CFCs.

D) increase in warming due to high levels of ozone in the troposphere.

E) depletion of ozone in the troposphere due to greenhouse gases.

33) CO2 is a greenhouse gas because it:

A) increases the heat capacity of the stratosphere.

B) increases the reflection of short-wave energy from the sun.

C) traps long-wave heat energy near Earth’s lower atmosphere.

D) traps short-wave energy near Earth’s lower atmosphere.

E) causes the destruction of ozone in the near-surface atmosphere.

34) Which major problem for land-based ecosystems would result from global warming?

A) A rise in sea levels would drive in competitors.

B) A danger would result for species that cannot migrate in response to habitat change.

C) The excess CO2 could be lethal.

D) Increased fire danger would result in northern United States and Canada.

35) Ecosystems in the United States experience seasonality because:

A) Earth is tilted with respect to the orbit around the sun.

B) the rotation of Earth causes a rhythmic circulation of Earth’s atmosphere.

C) Earth rotates on it’s axis relative to the sun.

D) there is a predictable seasonal solar activity cycle.

E) Earth is closer to the sun in summer and farther away in winter.

36) The “rain shadow” effect occurs because:

A) cloud shadows move from east to west, dropping moisture on the east of mountain ranges in the northern hemisphere.

B) cool air masses warm as they move closer to the sun, dropping moisture on the west side of mountains.

C) air cools as it rises and drops most of its moisture on one side of the mountain, and then mostly dry air moves to the other side of the mountain.

D) clouds don’t drop moisture over mountain chains.

E) precipitation patterns follow the tilt of Earth’s axis.

37) At about 30 degrees north and south of the equator there are dry regions on Earth. Why?

A) Warm air rises and evaporates, leaving dry, cool air with no clouds.

B) Cool air falls, is warmed, and absorbs moisture.

C) Warm air falls and absorbs moisture as it cools near the surface.

D) Cool air rises, and water condenses.

E) Air flows laterally across the land from the temperate zone.

38) Earth is generally hotter at the equator because:

A) the sun shines over the equator evenly through the year, rather than seasonally.

B) Earth’s rotation on a tilted axis increases seasonality.

C) the natural oval shape of Earth places the equator nearer the sun than the poles.

D) the Earth receives the most direct sunlight over the course of the year at the equator.

E) Earth’s rotation on a tilted axis creates an atmospheric drag at the equator, warming the air.

39) Which of the following best describes a biome?

A) large terrestrial regions with similar climate and similar types of plant life

B) small terrestrial regions with similar climate and the similar communities of organisms

C) three different classes of ecosystems based on high, medium, or low rainfall

D) three different classes of ecosystems based high, medium, or low temperature

40) Tundra is characterized by:

A) low rainfall, deep water penetration, and trees with a vibrant understory of moss.

B) high rainfall, slowly growing trees, and low temperatures.

C) low rainfall, coniferous trees, and permafrost.

D) low rainfall, dry soils, and permafrost.

E) low rainfall, seasonally wet soils, and permafrost.