Question

For the functioning of enzymes, which of the following statements is NOT correct?
A. An optimum temperature is needed
B. An optimum pH is needed.
C. They are substrate specific.
D. They always increase activation energy.

Answer 1

Hint: In our body, many biological reactions (chemical reaction in our body) take place and enzymes are the substances which help these reactions to proceed without any hindrance and quickly. Enzymes are used to catalyze reactions in the body or in short, enzymes are catalysts which catalyze reactions in the human body.

Complete Step by Step Answer:
All enzymes have active sites. As soon as enzyme get active, holoenzyme (if not activated, like apoenzyme) by the attack of non protein molecule (cofactor) on the protein part of enzyme (coenzyme), then, it attack on substrate and catalysis the reaction of that substrate.

For reaction, we need to supply energy to reactants and this energy should be greater than activation energy (minimum energy required to activate the reactants or start the reaction). Every reaction has its own activation energy, so, when a reaction has very high activation energy then it becomes difficult even to start the reaction. In that case, catalysts are used in the particular range of temperature and optimum pH value.

Catalyst (providing suitable surface) used to decrease the activation energy of any reaction and thus, help to increase the rate of formation of product or can say rate of forward reaction and also give good yield of major product. This is the same work of enzymes for biological reaction. Enzyme after activation attacks on substrate and accelerates the substrate to show reaction giving out suitable product. Enzymes always increase the rate of the reactions, decreasing the activation energy of the reaction.
Thus, the correct option is D as the enzyme does not increase the activation energy.

Note: It is important to note that every enzyme activates a specific reaction but not all or can say all reactions need a special enzyme to catalysis its reaction. Catalysts provide a suitable surface for reaction and decrease the activation energy of reaction to enhance the rate of forward reaction or backward reaction also in case of reversible reaction, remaining unaffected at the end of the reaction and released on the product side.