Which one of the following organisms may respire in the absence of oxygen?

What is the total number of $ATP$ molecules produced during alcoholic fermentation?

In which one of the following processes $CO_2$ is not released?

During anaerobic respiration in yeast,what are the end-products?

Identify the enzyme for the following reaction:
$CH_3COCOOH \longrightarrow CH_3CHO + CO_2$

In the following flow chart, replace the symbols $a$, $b$, $c$ and $d$ with appropriate terms. Briefly explain the process and give any two applications of it.