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Question Video: Describing How Enzymes Affect Biochemical Reactions Using a Graph Biology

The graph provided shows how the addition of an enzyme affects a biochemical reaction. What key aspect of this reaction has changed with the addition of an enzyme? [A] There have been no obvious changes. [B] The activation energy has been lowered. [C] The free energy of the reaction has increased. [D] The volume of products formed has decreased. [E] The time taken for the reaction to become complete has increased.

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Video Transcript

The graph provided shows how the addition of an enzyme affects a biochemical reaction. What key aspect of this reaction has changed with the addition of an enzyme? (A) There have been no obvious changes. (B) The activation energy has been lowered. (C) The free energy of the reaction has increased. (D) The volume of products formed has decreased. Or (E) the time taken for the reaction to become complete has increased.

Let’s start by reviewing some terms. An enzyme is a protein that catalyzes chemical reactions or helps those chemical reactions happen more effectively by binding the reactants of the reaction or the substrates and orienting them properly or otherwise preparing them for the chemical reaction to more easily occur. Through this type of action, we generally say that enzymes make chemical reactions more efficient by lowering the energy required for the reaction to occur.

In the graph that we’re provided with, we can see that we have reaction progress along the horizontal axis and free energy or the energy used or required for the reaction along the vertical axis. And we also see two lines, a red line and a green line, which correspond to the reaction happening with the enzyme or without the enzyme. We can see that both lines start and end in the same places and that they also have the same general shape, including this peak of energy that’s required towards the beginning of the reaction.

However, we can also see that the red line, which indicates the reaction without the enzyme, has a much higher peak than the green line, which indicates the reaction happening with the enzyme. And we can see that both of these peaks are labeled with this symbol 𝐸 sub a, which stands for energy of activation or activation energy. The activation energy is the energy required to get a reaction started.

So because the red line’s peak is higher, we can see that 𝐸 sub a, or activation energy, is higher for the reaction without the enzyme than the reaction with the enzyme. And this is the only major difference we see between the two lines in this graph. So what key aspect of this reaction has changed with the addition of an enzyme? In the graph, we can see that with the addition of an enzyme, the activation energy has been lowered.

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