Question

Steps of respiration are controlled by
A. Substrates
B. Enzymes
C. Hormones
D. Bile juice

Answer 1

The movement of oxygen from the outer environment into the cells in the tissues, and then transport the carbon dioxide in the opposite direction is known as respiration in a physiological manner. According to the biochemical definition, respiration is a metabolic process through which an organism can obtain energy by oxidizing the nutrients and then releasing the waste products.

Complete answer:
When a set of metabolic processes and reactions takes place in a cell of an organism for converting chemical energy provided by the oxygen molecule into ATP (Adenosine triphosphate), and then releasing the waste products is known as cellular respiration. Mainly catabolic reactions are involved in cellular respiration. Catabolic reactions are the reactions where a large molecule breaks into smaller molecules. There are three steps in which cellular respiration occurs, glycolysis, citric cycle, and oxidative phosphorylation.

Enzymes are the form of proteins which affect or catalyze the rate of chemical reaction without altering with the process of respiration

In the first step of respiration, which is glycolysis, various enzymes are used such as Hexokinase, Phospho hexose isomerase, Phosphofructokinase, Aldolase, and many others. Similarly in the next step, citric acid cycle enzymes like citrate synthase, Aconitase, Decarboxylase, and dehydrogenation are used. And in the last step of respiration that is, oxidative phosphorylation ATP synthase is used.

Therefore, it can be concluded that the steps of respiration are concluded by enzymes.
Hence, the correct answer is option (B).

Note: There are specific enzymes for catalyzing each reaction even on the cellular level. The main function of enzymes in the respiration reaction is assisting the transferred electrons from one molecule to the other. This transfer of electrons is termed as redox reactions, where a molecule loses an electron which gets coincided with another substance by adding that lost electron.