Long Essay Practice
AP Exam Review Fall 2014
LONG ESSAY #1
The diagram below represents two different forest communities, community 1 and community 2.
a. Analyze the factors involved in species diversity.
b. Calculate the percent of each community represented by species A.
c. Explain how two communities that contain the same number of species can differ in species diversity.
d. Predict and justify the impact on community stability in each forest community of a disease that affects species A.
RUBRIC: MAX 10 POINTS
Part a: Species Diversity (3 Points Max)
 (+1) Species diversity is comprised of species richness and relative abundance.
 (+1) Species richness is the number of species in a community.
 (+1) Relative abundance is the proportions of the community represented by the various species.
Part b: Calculations (2 Points Max)
 (+1) For community 1…A: 25%, B: 25%, C: 25%, and D: 25%
 (+1) For community 2…A: 80%, B: 5%, C: 5%, and D: 10%
Part c: Explanation (2 Points Max)
 (+1) Compared to a community with very high proportion of one species, a community with a more even proportion of species
is considered more diverse.
 (+1) Community 1 is considered more diverse because although species diversity is equal between the two communities, the
relative abundance is more equitable in community 1.
Part d: Prediction & Justification (3 Points Max)
 (+1) If the blight damaged species A, the community structure of community 2 would be most seriously impacted because
species A makes up 80% of the individual trees in community 2.
 (+1) Loss of species A from community 2 would result in large light gaps, more erosion, and greater loss of nutrients from the
community.
 (+1) Community 1 would be less seriously impacted, as its distribution of species is more equal.
 (+1) In general, more diverse communities are more stable.
LONG ESSAY #2
Photoperiodism and the control of flowering is a plant behavior essential to survival.
a. Describe the importance of the process to the plant’s life cycle.
b. Explain the mechanisms by which it is controlled, including triggers and responses.
c. Sketch a model that illustrates the key differences between short-day plant species and long-day plant species.
d. Discuss the evolutionary significance of this process.
RUBRIC: MAX 10 POINTS
Part a: (4 Points Max)
 (+1) Photoperiodism is any physiological response to a length of day or night.
 (+1) Many plants are classified by their photoperiod as either short-day plants or long-day plants.
 (+1) Short day plants will not flower unless they receive a critical period of darkness.
 (+1) Long day plants will not flower unless they receive a critical period of light.
Part b: (4 Points Max)
 (+1) Plants monitor the length of the night by the molecular switching of two forms of phytochrome pigment (Pr and Pfr).
 (+1) Phytochromes respond to a shift in red (r) light to far-red (fr) light.
 (+1) Plants produce phytochrome in the Pr form, and light causes Pr to switch to Pfr. The relative amounts of these pigments
provide a baseline for measuring the amount of sunlight in a day.
 (+1) The threshold to trigger flowering is called the critical dark period – so long-day plants and short-day plants actually
monitor and respond to the length of night.
Part c: (1 Point Max)
 Other similar models also earn a point for part C.
Part d: (1 Point Max)
 (+1) This mechanism of response to the length of daylight serves as an adaptation to ensure flowering resources are not
committed until growing conditions are most favorable for the survival of flowers, fruits, and seeds.
LONG ESSAY #3
The rate of photosynthesis for a given plant may vary with changes that occur in environmental temperature, wavelength of light,
and light intensity. Using a photosynthetic organism of your choice, choose only ONE of the three variables (temperature,
wavelength, or intensity) and for this variable
a. Design a controlled experiment to determine the effect of the variable on the rate of photosynthesis for the organism;
b. Explain how you would measure the rate of photosynthesis in your experiment;
c. Describe the results you would expect. Justify your expectation.
RUBRIC: MAX 10 POINTS
Part a: Experimental Design (3 Points Max)
Note: Score only the first variable manipulated, and the first factor used by the student to measure photosynthetic rate.
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(+1) The student stated a testable hypothesis in the “if…then…because” format, choosing only one of the three variables listed.
(+1) The student clearly stated the independent and dependent variable.
(+1) The student specified an appropriate control group for comparison.
(+1) The student identified and held constant at least three experimental factors that could affect photosynthetic rate.
Part b: Experimental Design (3 Points Max)
Note: A 3-point maximum can be earned if experiment will not work biologically. Examples: using an organism that is not
photosynthetic; using an apparatus that will not measure photosynthesis as designed.
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(+1) The student described how they would manipulate the independent variable.
(+1) The student described what was being measured to determine the rate of photosynthesis (CO 2 consumption, H2O
consumption, O2 or carbohydrate production, number of leaf disks floating, color change related to dye reaction of DPIP, etc.).
o Note: measurement described above MUST BE quantitative, not qualitative.
(+1) The student quantified the measurement of the variable (method and time frame of measurement).
o Note: this point awarded ONLY IF first two bulleted items are awarded.
(+1) The student verified results with appropriate sample size (>5) and repetition of experiment.
o Note: this point awarded ONLY IF first two bulleted items are awarded.
(+1) The student utilized statistical analysis of data (mean, t-test, chi-square, etc.).
o Note: this point awarded ONLY IF first two bulleted items are awarded.
(+1) The student designed an exemplary experiment that could be used to test the hypothesis stated.
o Note: this point awarded ONLY IF first two bulleted items are awarded.
Part c: Expected Results (2 Points Max)
 (+1) The student provided a verbal or
graphic description of expected results.
 (+1) The verbal or graphic results described
by student include the entire range of
biological activity.
 (+1) The graphs to the right represent 2point graphs, but to earn any points, graphs
must be accurately labeled.
Part c: Justification (2 Points Max)
 Temperature:
o Denatured enzymes as temperature increases
o Stomatal closings with high temperature limits CO2 intake
o Excessive water loss, less water available for photosynthesis
o Elegant elaboration
 Wavelength:
o Absorption/reflection of light by chlorophyll
o Accessory pigments absorbing green light
o Relation between wavelength and energy
o Elegant elaboration
 Intensity:
o More photons hit photosystems
o More e- flow in the electron transport system/time
o Plateau caused by limiting factors
o Elegant elaboration