PPTReview of Test 1

Test 1 Review
Chapters 1, 2, 3
The students decided to perform water quality tests on their model system.
List three water-quality tests that
could be conducted and explain what information each test provides. Include in your answers a
description of the impact of each factor on the health of the aquatic organisms.
Rubric- Question 1 Scoring Guidelines
Part a (Max 9 points): 1 point to be awarded for each abiotic test (3required) linked with a description of what it measures (1 point ea); for example the nitrate test
measures the concentration of nitrates (maximum 3 tests).
For each parameter a point to be awarded for an "impact" statement that links it to a specific effect on organisms. For example increased nitrate levels can lead to
algal blooms and ultimately lower dissolved oxygen levels.
No credit was given for stating an organism can only survive in a specific range of nitrates. Statements so general they could apply to numerous water quality tests
were not accepted.
Using the graph paper provided, plot the results that were obtained. Then, using the
same set of axes, draw and label an additional line/curve representing the results that
you would predict had the day been heavily overcast.
3pts with overcast line
Less light energy, less
Photosynthesis, lower Ox
C. Explain the biological processes that are operating in the lake to produce
the observed data. Explain also how these processes would account for your
prediction of results for a heavily overcast day.
(6pts)3 pts expl of production of oxygen and loss of oxygen at night resp)
C. Oxygen levels are produced through the process of
photosynthesis. The rate of Photosynthesis increases with
with the availability of light. We would expect the aquatic
system to have low oxygen levels early in the morning
because there was no light throughout the night. As the light
energy increases, so does the rate of photosynthesis as long
as all other requirements are present. Photosynthetic rate is
highest late in the afternoon because the levels of oxygen are
accumulating. As the light energy wanes so will the
photosynthetic rate.
The plants will begin using more oxygen during the process of
respiration and the levels of oxygen will begin to drop steadily
through the night.
The level of oxygen would never reach zero because ultimately there is a net gain of
D. Describe how the introduction of high levels of nutrients such as nitrates
and phosphates into the system would affect subsequent observations.
Explain your prediction
D. Phosphate is the number one limiting factor in aquatic systems.
Increasing the amount of phosphate would increase the growth rate of
algae and aquatic plants in the system. Additional nitrates would also
promote excess algal growth. The growth in turn, would deplete all
resources, massive die –off, deprives the water below of dissolved
oxygen, triggering fish kills. Normally, nitrogen compounds and
phosphate are necessary nutrients, but excess amounts cause
(4pts)3 pts expl of increase in photosynthesis ,plant growth increase, overpopulation,
depletion of resources, death, decomposition uses all available oxygen, hypoxic or
anaerobic environment,

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