Question 1

Nitrogen is often in short supply in terrestrial ecosystems because

Accepted Answer

A)  there is very little free nitrogen in the air. 
B)  atmospheric nitrogen exists primarily in the stratosphere and does not come into contact with terrestrial ecosystems. 
C)  atmospheric nitrogen cannot be used by most organisms. 
D)  nitrogen solubility in water is very low, and therefore aquatic nitrogen enters cells very slowly. 
E)  atmospheric nitrogen varies widely from location to location, and local shortages occur frequently.

Question 2

Which of the following statements about acid precipitation is false?

Accepted Answer

A)  Acids that enter the atmosphere primarily affect ecosystems located less than 100 kilometers from the source of the pollution. 
B)  Though lakes are very sensitive to acidification, their pH can return rapidly to normal values. 
C)  Regulation of emission sources has raised the pH of precipitation in many parts of the eastern United States in the last two decades. 
D)  Sulfuric acid and nitric acid from the burning of fossil fuels are the major causes of acid precipitation. 
E)  Organisms lost from freshwater ecosystems because of acidification may not return even decades after pH values have returned to normal.

Question 3

In studies of the nitrogen fixation of Elliott's milkpea, researchers found that increasing carbon dioxide increases nitrogen fixation at first, but then decreases it, even to a level that is below the baseline level. If a program were being designed to maintain high levels of nitrogen fixation, the best course of action would be to add

Accepted Answer

A)  even more carbon dioxide gas. 
B)  more nitrogen gas. 
C)  iron, molybdenum, and other micronutrients to the soil. 
D)  a combination of oxygen and nitrogen gases. 
E)  a competing species.

Question 4

Which of the following statements about the water cycle is false?

Accepted Answer

A)  There is a net movement of water vapor from oceans to terrestrial environments. 
B)  Precipitation exceeds evaporation on land. 
C)  Most of the water that evaporates from oceans is returned by run-off from land. 
D)  Transpiration makes a significant contribution to evaporative water loss from terrestrial ecosystems. 
E)  Evaporation exceeds precipitation over the seas.

Question 5

Less than half of the CO2 released to the atmosphere via human activities remains in the atmosphere. The rest may be found

Accepted Answer

A)  dissolved in the oceans. 
B)  stored on land. 
C)  above the stratosphere. 
D)  Both a and b 
E)  None of the above

Question 6

_______ energy drives almost all biological systems.

Accepted Answer

A)  Solar 
B)  Chemical 
C)  Physical 
D)  Mechanical 
E)  Electrical

Question 7

Water is the most dense at a temperature

Accepted Answer

A)  just above 0°C. 
B)  of 4°C. 
C)  of 20°C. 
D)  of 32°C. 
E)  of 37°C.

Question 8

The region of a lake in which the temperature drops rapidly as one descends is called the

Accepted Answer

A)  thermoregulation zone. 
B)  troposphere. 
C)  hydrological zone. 
D)  turnover zone. 
E)  thermocline.

Question 9

Which of the following is a major obstacle to the sustainable management of ecosystems?

Accepted Answer

A)  Many ecosystem services are considered "public goods" that have no market value. 
B)  The total economic value of a sustainably managed ecosystem is almost always lower than that of an intensively exploited ecosystem. 
C)  Most people are not aware of the extent to which human activities affect the functioning of ecosystems. 
D)  Both a and c 
E)  All of the above

Question 10

Unusual features of Earth as a planet that affect its ecosystem dynamics include

Accepted Answer

A)  lithospheric plates that move continuously. 
B)  atmospheric gases that moderate surface temperatures. 
C)  large amounts of water in liquid form. 
D)  a diversity of living organisms. 
E)  All of the above

Question 11

Carbon dioxide is called a greenhouse gas because

Accepted Answer

A)  it is used in greenhouses to increase plant growth. 
B)  it is transparent to heat, but traps sunlight. 
C)  it is transparent to sunlight, but traps heat. 
D)  it is transparent to both sunlight and heat. 
E)  it traps both sunlight and heat.

Question 12

The surface waters of lakes quickly become depleted of _______, while deeper waters become depleted of _______.

Accepted Answer

A)  oxygen; minerals 
B)  oxygen; nutrients 
C)  nutrients; minerals 
D)  nutrients; oxygen 
E)  groundwater; oxygen

Question 13

What would be the most likely effect on most plants (lacking symbiont microorganisms) if they were given additional nitrogen gas?

Accepted Answer

A)  The additional nitrogen gas would increase their growth rate. 
B)  The additional nitrogen gas would interfere with their photosynthesis, and thus would decrease their growth rate. 
C)  The additional nitrogen gas would accelerate their metabolic rate. 
D)  There would be no effect, because plants do not require nitrogen. 
E)  There would be no effect, because plants cannot use nitrogen gas.

Question 14

In which region of the ocean would you most likely find high rates of photosynthesis and dense animal populations?

Accepted Answer

A)  The troposphere 
B)  The upwelling zone 
C)  The hydrological zone 
D)  Areas distant from major land masses 
E)  None of the above

Question 15

Where is the largest reservoir of carbon in the global carbon cycle?

Accepted Answer

A)  Terrestrial ecosystems 
B)  Oceans 
C)  Atmosphere 
D)  Beneath the surface of Earth 
E)  Carbon is distributed evenly over the globe.

Question 16

Zones of upwelling near the shores of land masses have high primary production because such zones

Accepted Answer

A)  bring nutrients from the seafloor up to the surface. 
B)  are characterized by clear water that permits light to penetrate to an unusually great depth. 
C)  bring warm water to the surface. 
D)  trap nutrients washed into the ocean from nearby land masses. 
E)  have water of lower salinity than other oceanic regions.

Question 17

The sulfur cycle influences the global climate because

Accepted Answer

A)  sulfur compounds are important greenhouse gases. 
B)  sulfur compounds help transfer carbon from the atmosphere to the oceans. 
C)  sulfur compounds in the atmosphere are components of particles around which water condenses to form clouds. 
D)  sulfur compounds contribute to acid precipitation. 
E)  Both c and d

Question 18

Low levels of net primary production would likely be found

Accepted Answer

A)  in the Amazon. 
B)  in a moist area of Africa near the equator. 
C)  in a moist area of northern Canada. 
D)  in Vietnam. 
E)  None of the above

Question 19

Some nutrients are brought back to the surface near the coasts of continents, where offshore winds pushing surface waters away from shore cause cold bottom water to rise to the surface. The water in these upwelling zones

Accepted Answer

A)  is nutrient-poor. 
B)  is too cool to support abundant life. 
C)  is nutrient-rich. 
D)  is too warm to support abundant life. 
E)  has a moderate amount of nutrients.

Question 20

The _______ rate of absorption of carbon dioxide in the oceans is causing them to become more _______.

Accepted Answer

A)  decreasing; acidic 
B)  decreasing, alkaline 
C)  decreasing; productive 
D)  increasing; acidic 
E)  increasing; productive

Exam 58: Ecosystems and Global Ecology