2. why do you think the cell has a method for producing atp even when no oxygen is present?

In a "fight or flight" (life or death) situation, the body has to be ready to defend itself. As an example, if someone where trying to kill you, you would be able to run without getting tired. However, to do this your cells would have to go through anaerobic respiration (the creation of ATP without oxygen). It will not yield as much energy as aerobic respiration, and will result in lactic acid build up (which causes cramps), but it will allow you to be able to run or to fight for your life in a critical situation.

B] nitrogen fixationmight be wrong, so correct me.want extra on your answers? just go on my account and go on questions and answer, or ask in the comments!