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AMI Day 16

Welch – Science

AMI Day 16 (students that receive modifications should not answer question 6)

INSTRUCTIONS:  Read the passage and examine the graph.  Answer questions 1-6 on notebook paper and have them ready to turn in on the first day classes at Alpena School District resume.

Phosphorus Cycle

The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth.

On the land, phosphorus gradually becomes less available to plants over thousands of years, since it is slowly lost in runoff. Low concentration of phosphorus in soils reduces plant growth, and slows soil microbial growth - as shown in studies of soil microbial biomass.  Since phosphorus is found in low concentration it is referred to as a limiting nutrient of plant growth.  Locally, transformations of phosphorus are chemical, biological and microbiological: the major long-term transfers in the global cycle, however, are driven by tectonic movements in geologic time.

Humans have caused major changes to the global phosphorus cycle through shipping of phosphorus minerals, and use of phosphorus fertilizer, and also the shipping of food from farms to cities, where it is lost as effluent.

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1. According to the model, which of the following would not be an input of phosphorus into the soil.

  1. Humus
  2. Animal manures
  3. Dust
  4. Mineral fertilizers


2. Of the following, which one does not have a cyclical (cycle) pattern?

  1. Plant residues > Organic phosphorus > Mineralization > Soluble P > Plant Uptake
  2. Soluble P > Adsorption > Mineral surfaces > Desorption
  3. Secondary compounds > Dissolution > Soluble P > Precipitation
  4. Primary mineral > Weathering > Soluble P > Leaching

3. Algal blooms, like found on our nearby ponds covered with green vegetation, is a result of excess phosphorus.  Which of the following would be the most likely reason for the excess plant growth in these ponds due to the presence of phosphorus?

  1. Crop harvest
  2. Runoff
  3. Plant uptake
  4. Leaching

4. Locally, human activity has the greatest impact on the phosphorus cycle.  Which of the following would be associated with that impact?

  1. Mineral fertilizers
  2. Plant residues
  3. Animal manures and biosolids
  4. Weathering of primary minerals

5. Of the phosphorus inputs, which would be a man-made input.

  1. Atmospheric decomposition
  2. Mineral fertilizers
  3. Animal manures
  4. Plant residues

6.  Which of the following is best at long term removal of phosphorus from the soil?

  1. Crop harvest
  2. Runoff
  3. Plant uptake
  4. Leaching