Unformatted text preview: dark = gross productivity Net Productivity I Respiration Gross Productivity © 2008 The College Board. All rights reserved. Visit the College Board on the Web: www.collegeboard.com. AP® BIOLOGY 2008 SCORING GUIDELINES
Question 2 (continued)
(c) Explain the data presented by the graph, including a description of the relative rates of metabolic processes occurring at different depths of the pond. (1 point for each bullet; 4 points maximum) Explanation of data: • As depth is increased, the net primary productivity decreases because light decreases/lower rates of photosynthesis. Description of relative rates of metabolic process occurring at specific depths according to the graph (letters added to graph to simplify rubric): • A: The upper area of the graph is equally productive because light availability is not a limiting factor at the surface/ photosynthesis is not limited. A • B: The rapidly decreasing productivity region is a result of decreasing light B available for photosynthesis/photosynthesis is decreasing rapidly. • C: At 0 (the compensation point) the C photosynthetic product is equal to the D cell respiration requirements due to light availability/photosynthesis equals cell respiration. • D: Below 0 the photosynthetic product does not meet the cell respiration requirements due to insufficient light. Photosynthesis less than respiration. (d) Describe how the relationship between net primary productivity and depth would be expected to differ if new data were collected in mid-summer from the same pond. Explain your prediction. (1 point for each bullet; 2 points maximum) • • Description of a plausible predicti...
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