1. The term "dark reactions" was used for many years to describe the reactions for incorporating CO2in photosynthesis. Why was this term considered appropriate at the time and why is it considered inappropriate now?
2. Photorespiration is generally considered to be a wasteful process that decreases the yield of C3plants. What experiment would you propose to minimize the role of photorespiration in plants?
3. What would be the consequence in each of the following if the thioredoxins in chloroplasts were reduced not by ferredoxin but by NADPH as is the case for their cytosol counterparts? Assume NADPH is constant. Explain your answer.
A. Rate of starch synthesis.
B. Hexose monophosphate pool in chloroplasts in the dark.
C. Synthesis of malate in C4 plants.
D. Synthesis of malate in CAM plants assuming an adequate supply of phosphoenolpyruvate.
E. Activity of Rubisco.
4. There is current concern that the level of CO2is increasing in the biosphere due to the burning of fossil fuels. If the level of atmospheric CO2were to double, how would the following be affected? Explain your answer.
A. Rate of oxaloacetate synthesis in C4 plants.
B. Rate of 3-phosphoglycerate synthesis in C3 plants.
C. Rate of photorespiration in C3 plants.
D. Yield of wheat in Kansas.
E. Temperature of San Francisco Bay.
5. It has been known for many years that the cytosolic concentration of Pi in leaves increases when plants are shifted from light to dark. What effect does this change on each of the following?
A. The concentration of fructose-1,6-bisphosphate.
B. Synthesis of sucrose-6-phosphate from a fixed amount of fructose-6-phosphate.
C. Synthesis of sucrose from fructose-6-phosphate
D. Pool of dihydroxyacetone phosphate in chloroplasts.
6. Explain the adaptive advantage of chloroplast movement within mesophyll cells and solar tracking by leaves for light interception by plants.
7. Can heat absorption by leaves hinder leaf function? Explain your answer and describe ways in which leaves can dissipate absorbed heat. What is the major path for heat dissipation in leaves from irrigated cotton growing at high temperature in Arizona?