Question

multiple choice 1 point two nutrient solutions are maintained at the same ph. actively respiring mitochondria are isolated and placed into each of the two solutions. oxygen gas is bubbled into one solution. the other solution is depleted of available oxygen. which of the following best explains why atp production is greater in the tube with oxygen than in the tube without oxygen? in the presence of oxygen, glycolysis produces more atp than in the absence of oxygen. the rate of proton pumping across the inner mitochondrial membrane is lower in the sample without oxygen. electron transport is reduced in the absence of a plasma membrane. in the absence of oxygen, oxidative phosphorylation produces more atp than does fermentation.

Explanation:

Oxidative phosphorylation in mitochondria requires oxygen as the final electron - acceptor. In the presence of oxygen, the electron - transport chain and chemiosmosis can occur efficiently, leading to more ATP production through proton pumping across the inner mitochondrial membrane. Glycolysis is an anaerobic process but produces less ATP compared to oxidative phosphorylation. Without oxygen, electron transport is reduced, and proton pumping is less effective, resulting in lower ATP production.

Answer:

In the presence of oxygen, glycolysis produces more ATP than in the absence of oxygen. (This statement is incorrect as glycolysis produces the same amount of ATP with or without oxygen, but oxidative phosphorylation which occurs in the presence of oxygen produces more ATP overall). The rate of proton pumping across the inner mitochondrial membrane is lower in the sample without oxygen because electron transport is reduced in the absence of a plasma membrane (this is also incorrect as electron transport and proton pumping occur in mitochondria and not related to plasma membrane in this context). In the absence of oxygen, oxidative phosphorylation produces more ATP than does fermentation (this is incorrect as oxidative phosphorylation requires oxygen). The correct answer is that in the presence of oxygen, the electron - transport chain and associated proton pumping are more efficient, leading to greater ATP production compared to the situation without oxygen. But among the given options, the most relevant correct - concept related one is that the rate of proton pumping across the inner mitochondrial membrane is lower in the sample without oxygen as electron transport is reduced in the absence of oxygen.