Apart from temperature and pH, give two variables the scientist would have controlled when preparing the liquid medium cultures.

1

2

A student concluded that this investigation showed that ammonia inhibits nitrogenase activity in nitrogen-fixing bacteria. Use all the information to evaluate the student's conclusion.

Nitrogenase catalyses the reduction of nitrogen during nitrogen fixation. The reaction requires 16 molecules of ATP for each molecule of nitrogen that is reduced.

When ammonia inhibits nitrogenase activity, nitrogen-fixing bacteria may benefit.

Explain how.