S a process that's absent in cellular respiration in anaerobic organisms but present in aerobic organisms. Is a process that doesn't require oxygen.

Glycolysis through fermentation is the process that's absent in cellular respiration in anaerobic organisms but present in aerobic organisms, and it doesn't require oxygen.

Explanation:

First of all, this is a very difficult question because it could be interpreted with many different phenomenons. However, if we read it carefully we find the key element to understand it. The phenomenon we are looking for is not present in anaerobic organisms but present in aerobic organisms and it doesn't require oxygen. Both aerobic and anaerobic perform glycolysis the thing is that one o them will use oxygen and the other won't. And for not using oxygen they will also use fermentation. That is why it is the correct answer.

Krebs Cycle

Explanation:

Krebs cycle also known as citric acid cycle is the process in cellular respiration that doesn't require oxygen directly and it is absent in anaerobic respiration.