how many ATP molecules are produced where

Dear student 

Option 3 is correct. 
4 molecules of ATP are produced from Krebs cycle amd 2 molecules of ATP are produced from Glycolysis. 

Respiration is the process of breakdown of glucose with the help of molecular oxygen to produce ATP. It involves glycolysis and phosphorylation. 

Glycolysis is the first step of glucose breakdown which takes place in the absence of oxygen and converts one molecule of glucose into two molecules of pyruvate. During this process, 4 molecules of ATP are produced and 2 molecules of ATP are consumed. Thus, net ATP production is 2 ATP. 

Krebs cycle takes place in mitochondria and produces carrier molecules which pass through electron transport chain and produce 34 ATP molecules. 

Thus, total ATP production is 36 from the oxidation of 6 molecules of oxygen. Hence, form one molecule of oxygen ATP produced is 6.


Regards