Print out and complete the questions on the page. Feel free to answer these questions jointly with someone else in your class and include both names.
Questions 1 - 5 refer to Figure 1
1. The type of graph shown in Figure 1 is called: 2. This graph shows: A. the rate of O2 evolution at different times. B. the rate of photosynthesis at different irradiance levels. C. the rate of cellular respiration in the light. D. the rate of photosynthesis in different types of leaves. 3. The rate of photosynthesis in the region of the curve labeled "A" is determined by: A. the amount of light striking the leaf. B. the rate of the light-independent reactions. C. the rate of the light-dependent reactions. D. Answers A and C are correct. 4. The light level labeled "B" is called: 5. Which one of the following statements correctly describes photosynthesis at light levels at or above level "B"? A. The overall rate of photosynthesis is limited by the amount of CO2 available. B. Photosynthesis has stopped and O2 is no longer being produced. C. The amount of light is limiting the rate of photosynthesis. D. The light-dependent reactions are operating at the maximum rate.
6. Which one of the lines in Figure 2 shows how photosynthesis would be expected to change if the CO2 level in the leaf chamber were to be decreased?
7. Match the properties shown in Figure 3 with the characteristic of photosynthesis it measures:
__ slope A. irradiance level at which O2 release equals O2 uptake __ light compensation point B. shows the highest theoretical rate of photosynthesis in the leaf. __ y intercept C. beyond this point increasing irradiance does not increase __ light saturation point photosynthesis D. is a measure of the rate of O2 uptake processes in the leaf. E. reflects the efficiency at which light is used by the leaf
8. At light levels below the light compensation point: A. the Calvin-Benson cycle does not operate. B. fermentation is the predominant reaction. C. photorespiration causes a net uptake of O2. D. the light-dependent reactions operate in the absence of light. E. Both A and B 9. Calculate the photosynthesis rate for a leaf with an area of 0.032 m2 and O2 uptake at a rate of 0.075 %O2 /min. (Feel free to use the equations provided in the study quide and in the lab notebook). Show your calculations. 10. Figure 4 shows a response curve for a typical C3 plant. Draw a line that compares a response curve of a typical C4 plant.
11. Which statement below correctly describes C4 type plants? A. The light-dependent reactions occur in the day and CO2 fixation occurs at night. B. These plants possess a mechanism for elevating the level of CO2 in the chloroplast. C. The two stages of photosynthesis are separated in two different cell types. D. Both B and C are correct.
12. Figure 5 shows a typical O2 evolution curve. 1. Redraw the line as you would expect it to appear if the concentration of CO2 in the leaf chamber was higher during the experiment. 2. Redraw the line as expected if the stomates closed during the experiment. (Be sure to label your lines.)
13. What is the function of the light-dependent reaction of photosynthesis? A. production of CO2 and carbohydrate B. production of ATP and NADPH C. fixation of CO2 D. production of O2
14. Which of these answers best describes the function of the light-independent reactions? A. production of CO2 and carbohydrate B. production of ATP and NADPH C. fixation of CO2 D. production of O2 15. At one time, the light-independent reactions were referred to as the "dark reactions" of photosynthesis. Briefly explain why this terminology is misleading?
16. Add to Figure 6 two lines that show response curves for typical 'shade' and 'sun' type leaves. (Be sure to label the lines.) Identify the principal differences between these response curves.
17. The function of stomata is to: A. regulate movements of gasses into and out of the leaf. B. fix CO2 into carbohydrate. C. absorb light energy and transfer it to an electron. D. Both B and C are correct.
18. What happens during the process called photorespiration? A. The light-dependent reactions cease to function and photosynthesis stops. B. Plants carry on photosynthesis in the dark. C. O2 interferes with the light-independent reactions and slows photosynthesis. D. CO2 inhibits the light-independent reactions of photosynthesis.
19. As air temperature warms during the day, the rate of photosynthesis tends to increase. Why? A. Warm O2 is more reactive than cool O2. B. Warm CO2 is less reactive than cool CO2. C. Stomates close to conserve water and CO2. D. Enzyme rates increase with moderate warming.
20. Figure 7 shows a typical O2 evolution curve. Briefly explain why there is a lag phase at the beginning of the experiment.
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