SWES 200 Exam 2 2007

SWES 200 Exam 2 2007 - SWES 200, Exam II 23 October 2007...

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1 SWES 200, Exam II Name ______ KEY ________ 23 October 2007 True/False 1. T or F Some soil minerals have anion exchange capacity. (1) 2. T or F Most clay particles are positively (+) charged. (1) 3. T or F Soils formed under coniferous forests usually have higher concentrations of organic matter than those formed under grasslands. (1) 4. T or F There is more C in soils as organic matter than C in the atmosphere as CO 2 . (1) 5. T or F Other things being equal, soils in warm climates such as Arizona contain more organic matter than soils in colder regions such as North Dakota (1) 6. T or F Soils typically contain larger numbers of bacteria than fungi.(1) Multiple Choice (2 points each) 7. A mycorrhiza is a type of: a. plant b. actinomycete c. fungus d. bacteria e. none of the above are true 8. Organisms that use organic carbon for both their carbon source and their energy source are called _________. a. Chemoheterotrophs b. Chemoautotrophs c. Photoheterotrophs d. Photoautotrophs 9. The charges associated with organic colloids are due mostly to ___________. a. Protonation and deprotonation of functional groups b. Substitution of Al for Mg in the tetrahedral sheet c. Substitution of Si for Al in the tetrahedral sheet d. OH groups on the external surface of the tetrahedral layer
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2 10. The rhizosphere around a plant root differs from the bulk soil by which of the following. a. The rhizosphere has less CO 2 . b. The rhizosphere has lower levels of organic carbon because of root exudation. c. The rhizosphere has more microbial activity . d. The rhizosphere has more O 2 . e. All of the above. 11. Which statement about cation exchange (CEC) is true? a. CEC is usually higher in clays than in sands. b. CEC is reduced by the addition of organic matter to soils. c. CEC holds sulfate and nitrate to clays. .
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SWES 200 Exam 2 2007 - SWES 200, Exam II 23 October 2007...

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