Question

Which one of the following is a catabolic process?
A. Regulation
B. Photosynthesis
C. Digestion
D. Secretion

Answer 1

Hint: Several chemical reactions occur inside the body. All of these reactions are called metabolic reactions. Metabolism means when one product becomes a reactant for the other product. Metabolism consists of two pathways called catabolism and anabolism. Catabolism refers to the degradative pathway.

Complete answer:
Catabolism is a set of metabolic pathways that involves the breakdown of molecules into smaller units. The resultant molecules of a catabolic reaction are then either used in other anabolic reactions or are oxidized to release energy. Anabolic reactions are synthetic pathways that produce or secrete some molecules which are opposite to catabolic reactions. Thus, catabolism is regarded as breaking down aspects of metabolism. On the other hand, anabolism is a component of metabolism.
Digestion is a catabolic reaction as it involves the breakdown of complex nutrients into simpler molecules. This breakdown of nutrients is aided by various catabolic enzymes called digestive enzymes. There is a specific enzyme for the breakdown of a particular nutrient. Without digestive enzymes, there would be no breakdown of food into nutrient molecules which are further used to release energy. For example, proteases break down proteins in food. The proteins are broken down into amino acids. Amino acids are building blocks for various cellular components and are required for proper growth and development of the body. Thus, catabolic reactions are as essential as anabolic reactions to the body.

So, from the above discussion, we can conclude that option C) is correct.

Note: Amylase enzyme in the saliva of the mouth also performs catabolic reactions. It breaks down the complex food molecules into simpler ones. Partial digestion of food occurs inside the mouth due to amylase. The breakdown of ATP to release energy is also a catabolic process.