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Exam 1 -2010-Spring_key.pdf

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Department
Agronomy
Course Code
PCB 4043C
Professor
Christou

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Page 1 of 1  LASTNAME:______________________CODE:_________  GENERAL ECOLOGY PCB 4043C Spring 2010 EXAM I Exam instructions: --Write your last name and code on all the pages --Make sure that all 13 pages are attached. --You may not use calculators or other electronic aids. The math needed to solve a problem should be relatively simple. If you can't do the math, just show what needs to be calculated (e.g., "answer = 0.5 x .3") --If you get hung up on a problem, skip it; return to it after you’ve answered the “easy” problems. PAGE SECTION QUESTIONS POINTS SCORE POSSIBLE 2 I Silvia’s fill in the blanks 12 3-5 II Questions 1-7: Laura 28 6 Blank Page 0 7-8 III Questions 8- 12 : Silvia 24 9-11 IV Questions 13-17: Laura 22 12 Blank Page 0 13 V Question 18: Silvia 14 TOTAL 100 Page 2 of 2  LASTNAME:______________________CODE:_________  SECTION I. Silvia’s fill in the blanks (12 pts. total, 1pt. each blank). 1. The Gulf of Mexico’s dead zone is an area of hypoxic (less than 2 ppm dissolved oxygen) waters at the mouth of the Mississippi River caused by a process known as___eutrophication____________________. 2. ______N fixation________is the chemical transformation of N 2 to NH 3y Rhizobium bacteria, which develop a _______symbiotic_________relationship with plant roots. 3. The ratio of C:N:P in marine phytoplankton is 106:16:1, a remarkably constant relationship known as the _____Redfield Ratio_________________. 4. Roughly ____50___% of the earth’s photosynthesis occurs in the ocean. Most of it is performed by ________phytoplankton__and occurs mainly on upwelling and coastal regions. -3 5. The chemical form of P available for plant uptake is___Phosphate (PO 4 )___________. 6. ______Assimilation efficiency___is the ratio of assimilated energy / ingested energy. 7. An ecosystem service provided by the Florida everglades is _water filtration/tourism/air cleaning/water cleaning/habitat for animals and plants/biodiversity preservation/etc._. 8. The concentration of carbon dioxide in the atmosphere today is __375-385 ppm or 0.03%___. 9. A difference between the N and P cycles is that the __P_______cycle does not have an important atmospheric component. 10. Most energy that powers life on earth comes from ____the sun/light________________. Page 3 of 3  LASTNAME:______________________CODE:_________  SECTION II. Laura’s questions. Answer the following questions (28 pts. total, see each question for points). 1. A group of researchers is interested in using the first principles of physics, chemistry and biology to understand how concepts of metabolism can link individual organisms to the ecology of populations, communities and ecosystems. The majority of their work involves creating mathematical models. 1a. Does this research group do basic or applied research? (1 pt) basic 1b. Is this research more theoretical or empirical? (1 pt) theoretical 2. Ice is thawing on a temperate lake at the beginning of spring. During one morning of sampling, the deeper profile of the lake is 4°C and the profile above is 3°C. Does the 3°C water float or sink? (2 pts) floats 3. Of the following gases, CH 4, N2, N2O, O 2 CO ,2 3a. Which is most abundant? (2 pts) N 2 3b. Which are greenhouse gases? (2 pts) CH ,4N O2 CO 2 4. Circle the correct answer: 4a. The majority of the radiation entering the Earth’s atmosphere enters with what general wavelength? (2 pts) Longwave or shortwave 4b. Which type of energy passes less easily through greenhouse gases? (2 pts) Longwave or shortwave Page 4 of 4  LASTNAME:______________________CODE:_________  4c. If incoming radiation is absorbed by a surface (for example, soil), which of the following is true: (2 pts) a) The reradiated energy has a longer wavelength and has less energy than before being absorbed. b) The reradiated energy has a shorter wavelength and has more energy than before being absorbed. c) The reradiated energy has a shorter wavelength and less energy than before being absorbed. As a note, I could have phrased this better and this might be important for your general understanding. Energy that is re-radiated has (in general) longer wavelength and lower energy per photon. 4d. If incoming radiation is reflected by a surface (for example, snow), which of the following is true: (2 pts) a) The wavelength of reflected radiation is shorter than the initial radiation. b) The wavelength of reflected radiation is much longer than the initial radiation. c) The wavelength of reflected radiation is about the same as the initial radiation. 5. Use the outline of a Whittaker diagram below and small symbols to complete the following: 5a. Place an open circle where you would expect temperate seasonal forest. (1 pt) 5b. Place a square where you would expect tundra. (1 pt) 5c. Use a closed circle to indicate the area corresponding to tropical rainforest. (1 pt) Page 5 of 5  LASTNAME:______________________CODE:_________  6. Use the Walter climate diagrams below to answer the following questions. 6a. Answer True or False. Both of these sites are likely to be limited by water during a large part of the potential growing season. (2 pts) False 6b. In which site does the growing season last all year (use a and b to refer to the sites)? (2 pts) a 6c. Which of these figures could represent a temperate forest?(2 pts) b 7. Draw a graph showing a trade-off between seedling mortality and seed mass. Clearly label the x and y-axes and draw a line to show the trend that you would expect between the two variables. (3 pts) Page 6 of 6  LASTNAME:______________________CODE:_________  BLANK PAGE – EXTRA SPACE Page 7 of 7  LASTNAME:______________________CODE:_________  Part III. Silvia’s questions. Answer the following questions (24 pts. total, see each question for points). 8. Rank these global carbon reservoirs in order from largest to smallest, with 1 as the largest and six as the smallest (3 pts). ____Atmosphere __5__Atmosphere __4__Terrestrial vegetation and soils __3_Fossil fuels __1_Rocks __6_Marine biota __2_Intermediate and deep oceans 9. From the following pairs of conditions that influence decomposition of organic matter, choose the condition (either A or B) in each case that is conducive to faster decomposition (1 pt. each, 6 pts total) __ B____ A. Soil temperature of 4 °C B. soil temperature of 20 °C ___B____ A. Soil with 40% clay content B. soil with 10% clay content ___A____ A. Moist soil conditions B. wet soil conditions ___B___ A. High lignin content litter B. low lignin content in litter ___B___ A. Soil pH of 2 B. soil pH of 5 ___B___ A. Anoxic soil conditions B. well oxygenated soil conditions 10. Name two anthropogenic inputs to the N cycle and mention an important source for each. (4 pts). Anthropogenic= man-made, caused by humans Input: N fixation by planting N-fixing plants / Source: soy beans/legumes/ or any N-fixing crop Input: NO x emissions through burning of fossil fuels/ Source: Cars/factories/ industrial processes Input: N fixation through the Haber-Bosch method/ N fertilizers Note: Leaching or run‐off is not an input to a terrestrial ecosystem, so unless you specified that you were  talking about an aquatic system I gave you half points. In some cases you did not identify any specific  source for that input so I took out one point Page 8 of 8  LASTNAME:______________________CODE:_________  11. To test if phosphorus (P) limits productivity, an ecologist adds P fertilizer during several years to two systems, a tropical and a temperate forest. His results are summarized below. Tropical forest Temperate forest Increase in NPP (g C /m²/ year¹) Time (yrs) 11a. From this figure, what can you infer about P limitation in these two systems? (2 pts). Because the tropical forest responded to the fertilizer addition by increasing its NPP you can infer that the tropical forest was P limited. The temperate forest could have been slightly limited (or not limited by P) but the tropical forest had a higher level of limitation 11b. Given your knowledge of nutrient limitation on tropical and temperate forests, what
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