While researching the effects of light on chlorophyll synthesis in sorghum, you find that brief pulses of red light stimulates the synthesis of chlorophyll a and b. This would suggest that chlorophyll synthesis is directed by the Pr form of phytochrome.
Answer the following statement true (T) or false (F)
False
Clarify Question
• What is the key concept addressed by the question?
o The question is asking about the different forms of phytochrome.
• What type of thinking is required?
o This question is asking you to evaluate-phytochrome use in a plant.
• What key words does the question contain and what do they mean?
o Chlorophyll, which is a pigment that absorbs light that can be used in photosynthesis.
o Red light, which includes wavelengths of light that are used in photosynthesis.
o Phytochrome, which is a pigment-containing protein.
Gather Content
• What do you already know about "phytochromes and photosynthesis? How does it relate to the question?
o Active processes require the conversion of Pr to Pfr.
Consider Possibilities
• What other information is related to the question? Which information is most useful?
o Since chlorophyll synthesis requires active phytochrome, the Pr would need to become Pfr.
Choose Answer
• Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
o In the presence of red light, the Pr form of phytochrome is converted to the active form Pfr which would direct the synthesis of chlorophyll.
Reflect on Process
• Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
• Evaluate level:
This question asked you to evaluate the different forms of phytochrome. Answering this question correctly depended on your ability to evaluate when Pr and Pfr act. If you got the correct answer, well done! If you got an incorrect answer, where did the process break down? Did you remember that Pr differs from Pfr in that Pfr is required for active processes? Did you have trouble weighing the merits of Pr relative to Pfr to determine the correct answer?
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