Oceanography 320

Mid-term Examination

March 5, 2003

 

 

 

Name  __________________________________________

 

Social Security Number ____________________________

 

 

 

1)      The concentration of pollutant X is 40 ppm on trophic level five and 5 ppm on trophic level two.  If the ecological efficiency of the food chain is 20%, with what efficiency is pollutant X transferred from one trophic level to the next?

a)         10%

b)        20%

c)         30%

d)        40%

 

2)      Indicate whether the following transformations are examples of primary production (P), secondary production (S), or neither (N).

a)         Conversion of herbivore biomass to primary carnivore biomass

b)        Conversion of CO2 to organic carbon via photosynthesis

c)         Conversion of organic detritus to detritivore biomass

d)        Conversion of organic carbon to CO2 via respiration

e)         Conversion of CO2 to organic carbon via chemosynthesis

 

3)      The tendency for biomass in a food chain to decrease with increasing trophic level number is associated with which one of the following?

a)         Low ecological efficiency

b)        Eutrophication

c)         The microbial loop

d)        Carnivory

e)         Herbivory

 

4)      The tendency of the production of organic matter to exceed the consumption of organic matter is associated with which one of the following?

a)         Ecological pyramids

b)        Eutrophication

c)         Food chain magnification

d)        Detritus food chain

e)         Grazing food chain

 

 

 

5)      Which of the following statements is true of the critical depth?

a)         Net community production is zero at the critical depth.

b)        Net photosynthesis is zero at the critical depth.

c)         Gross photosynthesis is zero at the critical depth

d)        Chemosynthesis and photosynthesis are equal at the critical depth

e)         All of the above

f)          None of the above

 

6)      If water becomes murky because of sediment runoff

a)         Both the critical depth and the compensation depth would increase

b)        Both the critical depth and the compensation depth would decrease

c)         The critical depth would increase, and the compensation depth would decrease

d)        The critical depth would decrease, and the compensation depth would increase

 

7)      Phosphorus chemically bound in sediments is likely to be released when the sediments become anoxic because

a)         Polyphosphate is hydrolyzed to phosphate

b)        Anaerobic metabolism produces methane and carbon dioxide

c)         Calcium and magnesium are sequestered by organic chelators

d)        Ferric iron is reduced to ferrous iron

 

8)      The trace element that is believed to limit nitrogen fixation rates in the ocean is

a)         Iron

b)        Phosphorus

c)         Vanadium

d)        Copper

 

9)      Denitrification has a greater impact on the nitrogen cycle in the ocean than in lakes because

a)         Denitrification is limited by the low concentrations of phosphate in lakes

b)        High iron concentrations inhibit denitrification in lakes

c)         The residence time of bottom waters is much greater in the ocean

d)        Calcium and magnesium, both required for the production of nitrogenase, are much more abundant in the ocean

 

10)  A student performs a nutrient enrichment experiment involving nutrients X, Y, and Z.  Nutrient additions are made as follows:

 

 

Flask

Nutrients added

Result

Control

No additions

Water remains clear

A

X

Water remains clear

B

Y

Water remains clear

C

Z

Water remains clear

D

X + Y

Water remains clear

E

Y + Z

Water turns green

F

X + Y + Z

Water turns green

 

A logical interpretation of these results would be

                   a)  X and Y are both limiting.  Z is not limiting

                   b)  Y and Z are both limiting.  X is not limiting

                   c)  X and Z are both limiting.  Y is not limiting

                   c)  X, Y, and Z are all limiting

 

A lake is receiving wastewater in which the ratio of nitrogen to phosphorus is 6.  The ratio of nitrogen to phosphorus in the algae in the lake is 12.

 

11)  What would happen to the algae in the lake if the N were reduced by a factor of 8?

a)         No change

b)        Reduced by a factor of 2

c)         Reduced by a factor of 4

d)        Reduced by a factor of 8

 

12)  What would happen to the algae in the lake if the P were reduced by a factor of 8?

a)         No change

b)        Reduced by a factor of 2

c)         Reduced by a factor of 4

d)        Reduced by a factor of 8

 

13)  What would happen to the algae in the lake if the N were increased by a factor of 8?

a)         No change

b)        Increased by a factor of 2

c)         Increased by a factor of 4

d)        Increased by a factor of 8

 

14)  What would happen to the algae in the lake if the P were increased by a factor of 8?

a)         No change

b)        Increased by a factor of 2

c)         Increased by a factor of 4

d)        Increased by a factor of 8

 

15)  A freshwater lake in which the temperature never falls below 4oC is likely to be

a)         Monomictic with overturning occurring during the winter

b)        Monomictic with overturning occurring during the summer

c)         Dimictic with overturning occurring during the fall and spring

d)        Dimictic with overturning occurring during the summer and winter

 

16)  During winter in the North Atlantic Ocean, production is low and light limited in the surface waters because

a)         The compensation depth is deeper than the critical depth

b)        The mixed layer is deeper than the critical depth

c)         The compensation depth is deeper than the mixed layer

d)        The euphotic zone is deeper than the compensation depth

17)  Which of the following kinds of lakes is most susceptible to seasonal oxygen depletion?

a)         A shallow lake in which the epilimnion extends to the bottom

b)        A lake of intermediate depth in which the thickness of the hypolimnion is small compared to the depth of the lake

c)         A deep lake in which the thickness of the hypolimnion is more than 75% of the depth of the lake.

 

18)  In an estuary the net movement of water is

a)         Into the estuary near the bottom at the mouth and out of the estuary near the surface at the mouth

b)        Into the estuary near the surface at the head and out of the estuary near the bottom at the mouth

c)         Into the estuary near the surface at the mouth and out of the estuary near the surface at the head

d)        Into the estuary near the bottom at the head and out of the estuary near the bottom at the mouth.

 

19)  The extent of anoxia in the bottom waters of the Chesapeake Bay during the summer is positively correlated with the flow of the Susquehanna River in spring.  The explanation for this relationship is

a)         Due to industrial discharges of high BOD wastewater, the Susquehanna River has a very low oxygen concentration

b)        The freshwater from the Susquehanna River intensifies the stratification of the water column in the bay and isolates the bottom waters from the atmosphere

c)         The sediment transported by the Susquehanna River reduces light transmission through the water column in the bay and hence reduces the production of oxygen by benthic plants

d)        Due to the lack of riparian shade, the Susquehanna River water is much warmer than the water in the bay.  The higher temperature increases the respiration rate of organisms and hence causes the oxygen concentration to decline more rapidly than usual.

 

20)  The term stranded filth refers to

a)         Solids associated with sanitary sewage that are stranded in the pipes of a combined sewer system during dry weather

b)        Fecal material deposited by dogs, cats, and other animals on impervious surfaces in urban areas