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Unformatted text preview: tions will thus stop first. As a result, ATP production and NADPH production cease. The Calvin cycle can continue until stores of ATP and NADPH run out. 4 Problem Set 3 Chapters 8-10 BILD1 / Spring 2010 D r. Kiger 19) Why do plants need both cyclic and non-cyclic photophosphorylation to complete photosynthesis? Noncyclic photophosphorylation, the predominant pathway, produces an equal ratio of NADPH and ATP. The Calvin cycle, however, requires more ATP than NADPH to operate. Thus, the chloroplast must produce more ATP than NADPH. This is why the plant needs constant, low-level cyclic photophosphorylation that only makes ATP. 20) Define photorespiration. Compare and contrast the two strategies that plants living in hot climates have evolved to avoid it. Photorespiration occurs in plants in hot and/or dry climates when the stomata must close to avoid water loss. O2, a waste product of the light cycles thus builds up in the leaves. Photorespiration is the process by which the Rubisco enzyme is competitively outcompeted by increasing concentrations of O2 instead of only binding to CO2 when O2 levels are low. O2 binding to Rubi...
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This note was uploaded on 10/16/2010 for the course BILD 1 taught by Professor Boulanger during the Spring '08 term at UCSD.
- Spring '08