Question

You are trying to figure out an electron transport pathway including the following

electron transport molecules: B, K, T, Q and X. You do so by employing inhibitors for
various steps in the process. When you do, you get the following results:
Inhibitor Electron Transport Molecules Trapped in Reduced Form
Ticin Q & K
Digitin K
Estin T, K, Q & B
Lucin Q, K & T
What is the order of the molecules (the pathway) in the electron transport chain
suggested by the above data from the most reduced to the least reduced molecule?
A) K —> T —> B —> Q —> X
B) K —> X —> B —> Q —> T
C) K —> Q —> T —> B —> X
D) X —> B —> T —> Q —> K
E) T —> B —> K —> Q —> X

Answer 1

The correct order of the electron transport pathway, based on the results of the inhibitors used, is K —> Q —> T —> B —> X, which is option C.

Step-by-step explanation:

The student is asked to determine the electron transport pathway order based on experiments using various inhibitors of ETC (Electron Transport Chain) that result in certain electron transport molecules being trapped in a reduced form. The results of the inhibitors are as follows:

• Ticin traps Q & K in reduced form.
• Digitin traps K in reduced form.
• Estin traps T, K, Q & B in reduced form.
• Lucin traps Q, K & T in reduced form.

From the data, we can infer that Estin inhibits the earliest molecule in the chain because it causes the reduction of all molecules listed. Since Digitin only causes K to be reduced, K must be the first molecule in the chain. Following this logic, the pathway can be deduced by seeing the inhibitory effects downstream from each molecule.

The correct order from the most reduced to the least reduced molecule is K —> Q —> T —> B —> X, represented by option C in the list provided. This order is confirmed by looking at which molecules are reduced when a given inhibitor is used; the inhibitor blocks the chain at some point, and all molecules before that point will be reduced as they cannot pass their electrons forward.