If the DG of a reaction was -31.45 kJoules, you would know that:

Question

A.  the products have more free energy than the reactants.
B.  the reaction requires an energy input of 31.45 kJoules to proceed.
C.  the reaction most likely leads to development of a more ordered system.
D.  the reaction is spontaneous.

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 evolution? What other information is related to the question?

  Choose Answer
  Do you have all necessary information to break down the biochemical pathway?   

  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

D.  the reaction is spontaneous.

Clarify Question
  What is the key concept addressed by the question?
        · The question asks you to determine which step in a biochemical pathway would be likely to have evolved first.     
What type of thinking is required?
        · You are being asked to break down, or analyze, the steps in a biochemical pathway to determine the most suitable targets for early evolution.

  Gather Content
What do you already know about evolution? What other information is related to the question?
        · Remember that evolution is a series of changes that occur over time. Evolution is shaped by several factors, including natural selection that confers greater biological fitness for a pre-existing genetic makeup within a given environment.
        · A trait that evolved could convey greater biological fitness to some members of a population as compared to others without that trait for a given environment. The same can be said of molecules in a biochemical pathway. Inherited genetic changes that lead to molecular variation which in turn affects pathway productivity could provide enhanced function for the cells that contain them. That said, which steps in the biochemical pathway are most likely to be foundational to function and evolved first?

  Choose Answer
  Do you have all necessary information to break down the biochemical pathway?   
        · There are 5 components in the biochemical pathway, starting with P and eventually leading to T. Of these 5 components, which is most likely to have the key outcome and function? That would most likely be product T, which is the function end product and most likely to be used directly in cellular structure and/or function.
        · Working backwards from there, the steps that are most directly connected to product T represent the core chemistry in the pathway, which in this case is S -> T. All the other steps in the pathway are essentially preparation to get to the functional end point of product T. Being the most central to the pathway’s function, the S -> T reaction is likely to have evolved first.

  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?
        · This question asked you to determine which steps in a biochemical pathway are most likely to have evolved first.
        · If you got the answer correct, excellent! If you got an incorrect answer, did you remember how evolution occurs? Were you able to break down the steps in a biochemical pathway and determine which is most important? Were you able to infer the evolutionarysignificance of this step?