Readings for Chapter 10:

• Skim pages 190-195:  This portion of the chapter tells about the C3 pathway of photosynthetic carbon reduction (PCR) or carbon fixation.
• Read pages 195-197:  Activation and Regulation of the C3 PCR cycle.
• Skim pages 197-199:  This portion of the chapter tells about photorespiration.
• Read pages 199-200:  Why Photorespiration?
• Skim pages 200-204:  This portion of the chapter goes over the details of the C4 pathway.
• Read pages 204-205:  Ecological Significance of the C4 Syndrome
• Read pages 206-207:  CAM
• Read pages 208: Regulation of C4 and CAM
• Skim pages 208-212: Starch and Sucrose.

1. Be able to describe why the C3 pathway is said to be autocatalytic and why it is considered beneficial to the plant.
2. Be able to relate the C3 pathway mechanics to photorespiration.  Explain why a proper balance of CO₂ and O₂ is required by the plant.  In so doing, realize the importance of controlling transpiration at the same time.
3. Be able to discuss the ecological importance of photorespiration.
4. Be able to relate the importance of leaf structure in the C4 plant to the function of C4 metabolism.  Relate this to photorespiration.
5. Be able to compare and contrast C3 and C4 metabolism.
6. Be able to describe the significant way in which CAM differs from C4 metabolism.

The Photosynthetic Carbon Reduction (PCR) Cycle

1. Review the process behind C3 metabolism.  Pay particular attention to RuBisCo  (pages 189-195)

1. Why is it important to regulate the pool of intermediates in PCR?
2. How do light, pH, Mg²⁺, and CO₂ control Rubisco activity?
3. How does Rubisco activase function in controlling Rubisco activity?
4. There are four other light activated enzymes in PCR.  What mechanism for regulation is used with these four enzymes?

1. Review the process of photorespiration.  Familiarize yourself with the process, the organelles, the intermediates, and the enzymes involved.  (pages 197-199
2. Why does photorespiration occur?
3. Compare/contrast the problems that a C3 plant would have balancing transpiration, CO₂, and O₂ in a leaf.

1. Review the processes involved in C4 metabolism and the structure of the C4 leaf (pages 200-203)
2. Compare/contrast C3 and C4 metabolism processes for the following (pages 204-205
• Photorespiration
• CO2 compensation concentration
• Temperature Optimum
• Quantum yield
• Transpiration Ratio
• Light saturation

1. Review the process of CAM (pages 206-207)
2. What are the differences/similarities between C4 and CAM (pages 207)
3. Describe why CAM plants are well adapted to dry environments (pages 207)

1. How is PEPcase different in C4 and CAM plants?
2. How is PEPcase activated in the C4 plant?
3. How is activation of PEPcase accomplished in CAM plants?