Which of the following is a direct oxidation pathway that occurs without glycolysis?

Respiration occurs in .........

Respiration is a ......... process.

$A$ process is occurring throughout the day in an organism '$X$'. Cells are participating in this process. During this process, $ATP, CO_2,$ and water are evolved. It is not a light-dependent process. Is it a catabolic or an anabolic process?

Ascaris performs

Respiration is an energy-releasing and enzymatically controlled catabolic process which involves a step-wise oxidative breakdown of organic substances inside living cells. In this statement about respiration,explain the meaning of $(a)$ Step-wise oxidative breakdown $(b)$ Organic substances (used as substrates).