Oxygen is used only at the last step of aerobic respiration…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Oxygen is used only at the last step of aerobic respiration. A student says that it should not matter if it is missing in the first stages.
- Which stages do not need oxygen directly?
- What happens to the whole of aerobic respiration if oxygen is missing?
- What does the cell do for ATP then?
Need a reminder? The key ideaShow
Electrons in the chain pump protons into the intermembrane space. The protons flow back through ATP synthase, whose F head makes ATP and whose F part is the channel. Two protons pass for each ATP. Without oxygen the chain stops. Substrate level phosphorylation needs no membrane, and photophosphorylation is driven by light.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Glycolysis, the link reaction and the Krebs cycle do not use oxygen directly.
Step 2. (b) The chain stops, because there is no final acceptor. NADH and FADH are not changed back, so the link reaction and the Krebs cycle stop for want of NAD and FAD. No ATP is made by ATP synthase.
Step 3. (c) The cell can only go on with glycolysis and fermentation, which give a net gain of 2 ATP for each glucose.
Answer: (a) the three earlier stages; (b) the whole of aerobic respiration stops; (c) glycolysis and fermentation.
Discussion (0)
Log in to join the discussion.
Loading…