The number of glyceraldehyde-3-phosphate molecules that would be produced from 24 turns of the Calvin cycle would be

Question

A.  6
B.  8
C.  4
D.  12
E.  48

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 the Calvin cycle and photosynthesis? What other information is related to the question?

  Choose Answer
Do you have all the information needed to determine the likely outcome?

  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

B.  8

Clarify Question
What is the key concept addressed by the question?
        · The question asks you to determine how many molecules of glyceraldehyde 3-phosphate would be produced from 24 turns of the Calvin cycle.
What type of thinking is required?
        · You are being asked to calculate, or analyze, the number of glyceraldehyde 3-phosphate produced when the Calvin cycle turns 24 times.

  Gather Content
What do you already know about the Calvin cycle and photosynthesis? What other information is related to the question?
        · Recall that the biological function of the Calvin cycle is to fix carbon from the atmosphere into inorganic molecule. The Calvin cycle uses ATP and NADPH produced during the light reactions to fix inorganic carbon into inorganic form within the stroma of chloroplasts.
        · Remember that the Calvin cycle is an iterative process, meaning that carbon dioxide is accepted, molecules are transformed, excess carbohydrate is harvested, and new acceptor molecules are regenerated. Given what you know about the Calvin cycle, how many turns are required in order to produce one glyceraldehyde-3-phosphate molecule?

  Choose Answer
Do you have all the information needed to determine the likely outcome?
        · Remember that during the Calvin cycle, RuBP binds to a single carbon dioxide molecule and produces a six-carbon molecule that is then converted into two three-carbon molecules of 3-phosphoglycerate. Each of these molecules is subsequently converted into two three-carbon glyceraldehyde 3-phosphate molecules.
        · The ability of the Calvin cycle to keep operating is dependent on the regeneration of RuBP. Excess glyceraldehyde 3-phosphate molecules are harvested and use to make glucose, whereas other glyceraldehyde 3-phosphate molecules are eventually converted back into RuBP. The trick is knowing how many turns of the Calvin cycle are needed, given the need to regenerate RuBP.
        · Essentially, one carbon dioxide molecule is incorporated into an organic molecule for every turn of the Calvin cycle. Glyceraldehyde-3-phosphate is a 3-carbon molecule, so that means the Calvin cycle will have to turn three times. Since the problem indicates there are 24 turns total, that means 24 turns divided by 3 carbons in each turn of the Calvin cycle for each glyceraldehyde-3-phosphate molecule would equal 8 glyceraldehyde-3-phosphate molecules would be produced.

  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 analyze the Calvin cycle to determine how many glyceraldehyde 3-phosphate molecules would be produced from 24 turns.
        · If you got the correct answer, nice job! If you got an incorrect answer, did you recall that the Calvin cycle essentially requires a turn for each carbon that is fixed? Did you remember that eachglyceraldehyde-3-phosphate molecule contained three carbons? Were you able to calculate the number of glyceraldehyde-3-phosphate molecules given 24 turns of the Calvin cycle?