Which of the following is a catabolic reaction?
(a)Intercellular digestion
(b)Intracellular digestion
(c)Respiration
(d)All of the above

Hint: In catabolic reactions, large and complex molecules are broken down into smaller ones within a cell. In this hydrolysis reactions are used to break the bonds between two complex molecules.

Complete answer:
When large and complex molecules are broken down into simpler molecules by an exergonic process, it is called a catabolic reaction. In the case of Intercellular digestion, the molecules break down outside the cell, in the alimentary canal, and get absorbed whereas the Intracellular one takes place inside the cytoplasm of the organisms and like an Intercellular one is also the breakdown of large molecules. In the case of respiration, the large molecules of glucose are broken down to produce energy for the body. Therefore, all these are the catabolic processes.

Additional Information: Let us know more about all the processes:
Intercellular digestion- This type of digestion takes place in the alimentary canal instead of the inside of the cell and the products are absorbed into the cells. An example of this type of digestion is the digestion process in humans.
Intracellular digestion- It occurs inside the cell of the organisms and diffuses into the cytoplasm. Mainly this type of digestion is seen in unicellular organisms. It is a less efficient type of digestion.
Respiration- It is a biochemical process and occurs in almost all organisms and is the process of releasing energy from the complex organic substances. This is also of two types- aerobic and anaerobic. In aerobic glucose breaks down and products contain carbon dioxide, water, and ATP. In anaerobic ones, glucose breaks down into alcohol, carbon dioxide, and ATP.
Therefore, the correct answer to the question is “all of the above”.

Note: Catabolism or catabolic reactions have an important role in the functioning of cells. The monomers produced by these reactions such as fatty acids, monosaccharides, nucleotides, etc are used in different functions of the body. Other examples of catabolism are glycolysis, breaking of muscle proteins, breaking of fats, etc. Catabolism is controlled by many hormones such as cortisol, glucagon, adrenaline, etc.