Final answer:
The product in an enzymatic reaction is formed by enzyme-substrate interactions where the enzyme lowers the energy of activation. Enzyme concentration limits the reaction rate when it is lower than substrate concentration. Without an enzyme, reactions stop or slow down significantly.
Step-by-step explanation:
In enzymatic reactions, such as the one described in the question where enzyme A and enzyme B catalyze the same reaction, the product formation is dependent on the interaction between the enzyme and its substrate. Enzymes lower the energy of activation, allowing the substrate to reach a transient state more quickly, resulting in the formation of product. When the concentration of the enzyme is lower than the concentration of the substrate, the reaction rate is limited by the concentration of the enzyme.
In the scenario described, it is not clear what 'enzyme x' refers to since it is not mentioned in the reference information. Assuming 'enzyme x' is a typo and the question refers to either enzyme A or B, it is important to note that these enzymes use a CH₂R radical to facilitate the removal and transfer of a hydrogen atom, which leads to the formation of a new radical and ultimately gives the product.
If an enzyme is absent or not functioning, the reaction will either stop or proceed much more slowly (option b from the reference information). Thus, the presence and activity of an enzyme are critical for the efficient progression of biological reactions.