This preview shows page 1. Sign up to view the full content.
Unformatted text preview: BIOC 460 Spring 2010 Photosynthesis and Calvin Cycle Problem Set Reading Chapter 19 and Chapter 20.1 and 20.2 Problems Chapter 19: 1 and 5, Chapter 20: 2, 3, 6, 7 Then try these: 1. Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) blocks electron flow from Photosystem II to Photosystem I. What effect (if any) will it have on: Oxygen production? O2 production will stop because photosystem II will remain reduced Photophosphorylation? No proton gradient will be generated in the chloroplast, so photophosphorylation will not occur. Oxidative phosphorylation? Diuron does not inhibit the mitochondrial ETC, so oxidative phosphorylation will occur (as long as there is glucose or fats available). Explain your answers. 2. What effect (if any) would the uncoupling molecule dinitrophenol (DNP) have on Photophosphorylation? DNP will disrupt the proton gradient in the chloroplast, therefore photophosphorylation will slow or stop NADPH production? No effect, photosynthetic electron transport will continue in the presence of DNP, therefore NADP+ will continue to be reduced to NADPH Oxidative phosphorylation? DNP will disrupt the proton gradient in the mitochondria, therefore oxidative phosphorylation will slow/stop Explain your answers 3. Predict the effect of increased oxygen pressure [O2] on carbon assimilation. Explain your answer. Increasing the [O2] will increase the oxygenase activity of Rubisco (i.e. increase photorespiration) and lower the efficiency of carbon assimilation. 4. Give two reasons that the Calvin cycle does not occur in the dark. 1) Rubisco, the regulated enzyme in the Calvin cycle, is stimulated by light 2) ATP and NADPH, which come from the "light reaction," will are rapidly depleted in the absence of light ...
View Full Document
This note was uploaded on 05/06/2010 for the course BIOC 460 taught by Professor Ziegler during the Spring '07 term at Arizona.
- Spring '07