Question

Which of the diagrams illustrates the way in which the rate of an enzyme-controlled reaction depends on substrate concentration? * А B Rate of reaction MÚN Substrate concentration A B D

Answer 1

Enzyme controlled reaction: Enzyme controlled reaction are those reactions which are assisted by enzyme molecules. Enzyme molecules are not substrate molecules, they are a part of reaction and help in increasing the rate of reaction. At the end of the reaction enzyme molecules are received back in its oridginal state.

Rate of enzyme controlled reaction is a function of the concentration of substrate among other factors.

Dring enzyme controlled reactions, enzyme binds themselves to the active sites present on the substrate molecules and carry our the transformation of substrate into product molecule.

With high concentration of substrate molecules, active sites present for enzyme to bind to also increases. As more number of active sites assist faster transformation, the rate of reaction is also increased.

This phenomena is observed until all the available enzyme molecules are bonded to the substrate active sites. This is a saturation point. From here further increase in the concentration of substrate will not affect the rate of the reaction, as there are no more enzyme molecules available for binding to the increasing number of active sites.

Among the given options, in option A rate of reaction increases with increase in the concentration of the substrate until a certain point after which the rate of reaction becomes constant. This graph is consistent with the above explanation.

In option B, there is constant increase in the rate of reaction with increasing substrate concentration. This graph does not obey the above explanation.

In option C, the rate of reaction increases gradually at first and then rapidly with increasing substrate concentration. This graph too does not obey the above explanation.

In option D, rate of reaction decreases with increase in concentration of the substrate, This graph opposes the actual phenomena.

Therefore, graph A illustrates the way in which the rate of enzyme controlled reaction depends upon the substrate concentration.