Which is a mechanism by which enzymes increase the rate of reactions

A)  Strengthening the bonds that hold reactants together
B)  Changing endergonic reactions into exergonic ones
C)  Increasing the internal temperature of organisms
D)  Bringing together reactants so they can more easily bond
E)None of the above
 

I know D is the answer, but could you explain why?

In order to react, molecules have to collide from the required directions. Without enzymes, molecules collide with each other in random orientations, and only a small fraction of them do so in a manner that allows them to react. Enzymes can help orient reactants so the bonds are more readily formed.

Think of the enzyme like a person grabbing things (let's say dollar bills) from the air. You will grab those dollars faster if there were more dollars in your reach than if they were spaced further apart, right?

Same principle with enzymes.


FYI, C is also true because for some reactions, you need input of energy for reactions to occur; increasing heat will make it easier for enzymes to work.

If an enzyme can place the reactants in a more beneficial position to form the new bond, then it takes less energy to make the reaction happen.