In the absence of oxygen, what is the net gain of atp for each glucose molecule that enters glycolysis?
a. because in the absence of oxygen,
b. no atp can be made four atp up to 30 atp none,
c. because all of the available energy remains in either lactate or ethanol two atp
d. none

During anaerobic oxidation of a glucose molecule 2 ATP molecules are gained as the net profit. It is because here is no Krebs cycle and electron transport chain in anaerobic respiration.

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.