If the Calvin cycle were to be temporarily restricted, the highest concentration of NADPH would likely be in the

Question

A.  thylakoid space.
B.  thylakoid membrane.
C.  stroma.
D.  chloroplast outer membrane.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

  Gather Content
What do you already know about NADPH, where it is produced, and where it is used? What other information is related to the question?

  Choose Answer
Do you have all necessary information to determine what type of reaction is taking place?

  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?

Answer 1

C.  stroma.

Clarify Question
What is the key concept addressed by the question?
        · The question asks you to decipher where the highest concentration of NADPH would be located if the Calvin cycle were to be temporarily restricted.
What type of thinking is required?
        · You are being asked to break down, or analyze, photosynthetic processes and where they occur to determine where the highest concentration of NADPH would be located following restriction of the Calvin cycle.

  Gather Content
What do you already know about NADPH, where it is produced, and where it is used? What other information is related to the question?
        · Recall that photosynthesis is comprised of the light reactions, which produces ATP, NADPH, and oxygen and the Calvin cycle, which produces organic molecules from inorganic carbon dioxide. The first phase of photosynthesis includes the light reactions, where energy from the sun is captured using molecules like chlorophyll to remove electrons from water, excite them to a higher energy level, and to use redox reactions in order to produce ATP and NADPH.
        · The second phase of photosynthesis includes the Calvin cycle, which uses the ATP and NADPH products of the light reactions to fix inorganic carbon into an organic form within chloroplasts. If the Calvin cycle were to be restricted, what would happen to you NADPH concentration as a result?

  Choose Answer
Do you have all necessary information to determine what type of reaction is taking place?
        · The light reactions of photosynthesis, which occurs in the thylakoid membrane, produce ATP and NADPH. While both of these molecules are important to the Calvin cycle, if the Calvin cycle were restricted they would still continue to be produced because there is no restriction in light.
        · Since NADPH is required to help drive the Calvin cycle, and this occurs in the stroma, a restriction of the Calvin cycle would allow NADPH to accumulate, leading to a high concentration. This leads one to conclude the stroma is where the highest concentration of NADPH would be located.

  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?
        · Answering this question correctly depended on your ability to apply what you know about chloroplast anatomy and NADPH production to determine where the highest concentration of NADPH would be located if the Calvin cycle were to be temporarily restricted.
        · If you got a correct answer, excellent! If you got an incorrect answer, did you recall that the light reactions produce the NADPH used by the Calvin cycle? Did you recall that the light reactions occur in the thylakoid membrane and involved in the thylakoid space? Were you able to infer restriction of the Calvin cycle would allow NADPH to accumulate in the stroma where it is normally used?