Introduction to Biochemistry - End of session 3.3 assessment

I failed this one, with a careless mistake. Notice the word "regenerate", therefore the answer is obviously NAD+ and ATP.

ATP synthesis is coupled to redox reactions with an ion gradient.

This is really just checking the numbers in the video, the order is as follow:

Oxygen
Nitrate
Ferric iron
Sulfate
Carbon dioxide

All of the statements above are correct, and all of them have impact. It boils down to which one is most substantial.

Here are the correct answers:

Nitrate is a major limiting nutrient for plants.
Denitrifying bacteria remove nitrate from the soil.

All we need to do is to list them in oxidation state order:

Nitrate -> Nitrite -> Nitric Oxide -> Nitrous Oxide -> Dinitrogen