1. You have conducted an experiment using litterbags to assess the effect of lig
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Question
1. You have conducted an experiment using litterbags to assess the effect of lignin content on leaf decomposition rate. You selected 6 tree species with a range of leaf lignin levels. Which of the following is a plausible prediction for your study?
E. The CO2 captured in the bags will increase over time.
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2. Which of the following statements about nutrient cycles is FALSE?
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3. You have been asked to draw a graph of litter decomposition in a forest over time. Your graph has the rate of carbon lost on the y-axis and time on the x-axis. It begins at 100 percent and has a strong decline for the first portion, but then it levels off with a far lower slope as time continues. Please explain this trend.
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4. Roots exude high-quality, energy-rich carbon into the rhizosphere. It is hypothesized that this exudate functions to enhance decomposition rates. All of the following lend support to this hypothesis with one exception. Choose the EXCEPTION.
A. The carbohydrates exuded from plant roots may account for as much as 40 percent of dry matter production of plants.
B. Bacterial decomposition rates are much higher in the presence of these exudates.
C. Bacteria have been found in mutualisms with plant roots and they grow much more slowly without the root exudates.
D. Plants release CO2 gas into the rhizosphere to alter the pH and cause increased mobility of cation nutrients.
E. When provided with exudates, bacterial growth is limited most strongly by nutrient availability because the exudates are energy rich, but very low in nitrogen.
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5. Which of the following statements concerning the influence of currents in vertical transport of nutrients is true?
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6. What is swidden agriculture?
A. The biomass of leaf litter bags will increase more in plants with higher leaf lignin content. B. The biomass of leaf litter in the bags will be greater in leaves with higher lignin content after the same length of time. C. The leaf litter bags cannot be used to conduct this experiment. D. The biomass of leaf litter in the bags will be lower in leaves with higher lignin content after the same length of time.E. The CO2 captured in the bags will increase over time.
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2. Which of the following statements about nutrient cycles is FALSE?
A. Litterbag experiments are useful for determining the changes in nitrogen content within dead leaves. B. After the initial period of decomposition, nitrogen content of leaf litter increases. C. The nitrogen level in leaf litter declines at the onset of decomposition. D. As mineralization continues, the nitrogen concentration in the leaf litter can rise above 100 percent. E. Leaves with lower nitrogen content are of higher quality for decomposers.Explanation / Answer
4.When provided with exudates, bacterial growth is limited most strongly by nutrient availability because the exudates are energy rich, but very low in nitrogen
5. Along the western margins of the continents, the surface waters are pushed offshore by the Coriolis effect, resulting in deeper, more nutrient-rich waters being transported vertically to the surface.
6. swidden agriculture is a form of traditional agriculture that is being employed in many parts of the tropics to meet the ever-increasing demand for land.
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