VCAA 2006 Bio Question

[InsaneMcFries]

Question 4
2,4-dinitrophenol is a chemical that is toxic to mitochondria. When added to mitochondria this chemical allows
electron transport to occur but prevents the phosphorylation of ADP to ATP. The chemical achieves this by
breaking the essential link between electron transport and ATP synthesis. This toxin causes mitochondria to
produce heat instead of ATP. The greater the amount of toxin added, the quicker is its action.

a. If mitochondria are poisoned with 2,4-dinitrophenol by what process could a plant cell produce more
ATP?

I answered (abstractly, I'll admit) the light dependent reaction of photosynthesis.

Acceptable answers were anaerobic respiration, glycolysis or fermentation.
The most common incorrect answers given were photosynthesis and aerobic respiration.

I know the answers say it is wrong, but would specifying the light dependent reaction actually have helped my case in the exam? It's obvious now that my answer was offhand and that glycolysis is obvious, but I thought my answer had some merit. The plant cell is technically producing more ATP. It is also producing it somewhere other than the mitochondria, and the question specifically states the mitochondria is poisoned.

[Scooby]

Probably not. The light-dependent reactions do produce ATP, but since all of this is then used in the light-independent reactions, it wouldn't allow the plant cell to produce more ATP. There is no net production of ATP by photosynthesis. 

Even if the mitochondria were poisoned by this 2,4-dinitrophenol, glycolysis and anaerobic respiration could still occur, even if the mitochondria are completely inactivated by the poison, because they take place in the cytoplasm  

[InsaneMcFries]

Yeah I understand that, thanks for the input. I honestly have no idea why I chose to use that instead of glycolysis haha. Oh well.