Answer:
α- ketoglutarate → NADP+ → Oxaloacetate → O2.
Step-by-step explanation:
The ability of an molecule or a compound to donate or accept electron can be related to their electron affinity.
The more positive the electron affinity is ; the more likeliness such compound is known to be as an electron acceptor which accepts . Also the less positive the electron affinity is the more likeness such compound will be known to be as an electron donor which donates electron
The electron affinity of a compound to accept or donate electron can be related to their reduction potential value (Redox Value).
From the information given ; we have α –ketoglutarate, Oxaloacetate, O2, NADP+ and we are to arrange in an increasing tendency to donate electrons.
i.e from the least tendency to donate electron to the highest tendency to donate electron.
The reduction potential value (Redox Value) of the compounds and molecule given are:
α –ketoglutarate ---> - 0.38 since α- ketoglutarate will react with CO2, it gives isocitrate
Oxaloacetate ----> - 0.18 since Oxaloacetate will react with two moles of hydrogen ion and electrons respectively to give Malate
O2 ------> + 0.82 since O2 will react with 4 moles of hydrogen ion and electrons respectively to give 2 moles of water
NADP+ ------> - 0.32 since NADP+ will react with two moles of electrons and one mole of hydrogen ion to give NADPH
Again; lets recall the less positive the electron affinity is the more likeness such compound will be known to be as an electron donor which donates electron.
So to arrange the given substances in order of increasing tendency to donate electrons since we've known their standard reduction potential value (Redox Value); we have the increasing order as:
α- ketoglutarate → NADP+ → Oxaloacetate → O2.