Question Video: Interpreting Data on Enzyme-Controlled Reactions | Nagwa Question Video: Interpreting Data on Enzyme-Controlled Reactions | Nagwa

Question Video: Interpreting Data on Enzyme-Controlled Reactions Biology • Second Year of Secondary School

The enzyme catalase catalyzes the reaction that breaks down hydrogen peroxide into water and oxygen. The table shows how much oxygen is produced over time when this reaction occurs with and without catalase. In which reaction is the rate of oxygen production lower?

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Video Transcript

The enzyme catalase catalyzes the reaction that breaks down hydrogen peroxide into water and oxygen. The table shows how much oxygen is produced over time when this reaction occurs with and without catalase. In which reaction is the rate of oxygen production lower?

Here, we are asked about a specific enzyme called catalase. However, a basic understanding of enzymes can also help us to answer this question. Let’s review what an enzyme is and why they are so important in the human body.

Enzymes are proteins within the body that are sometimes called biological catalysts. This is because enzymes will catalyze or speed up chemical reactions. In a chemical reaction, a reactant is transformed into a product. An enzyme can speed up this process by binding to the reactant or reactants. When an enzyme is involved in the reaction, the reactant that binds to the enzyme’s active site is called substrate. The so formed enzyme–substrate complex helps to form or destruct bonds within the substrate.

In our question, catalase is the enzyme and hydrogen peroxide is the substrate. We know this because we are told that catalase breaks down the hydrogen peroxide. Our products, in this case, are water and oxygen. Since hydrogen peroxide is a harmful molecule in the human body, this reaction is very important.

Let’s return to our question, which asks us about the rate of oxygen production. We might be able to answer it without even looking at the table. We are told that catalase is an enzyme. And we know that enzymes speed up reactions. So the reaction with the enzyme should have a higher rate This means that in the reaction with catalase, more hydrogen peroxide molecules will be converted to water and oxygen per unit time.

Let’s check if that is correct by studying the table. In order to calculate the rate of production, we can find the difference in oxygen production and divide it by how much time is passed. For the reaction without catalase, the rate of oxygen production for the first 20 seconds would be five minus zero divided by 20 minus zero. The rate of oxygen produced is therefore 0.25. By comparison, the reaction with catalase will produce oxygen at a rate of 1.15. We can see that the rate of reaction is indeed higher with the catalase compared to without catalase.

This trend continues if we look at the time between 20 and 40 seconds. For the reaction without catalase, oxygen is produced at a rate of 11 minus five divided by 40 minus 20, which equals 0.3. For the reaction with catalase, this rate is 35 minus 23 divided by 40 minus 20, which equals 0.6. We can continue to calculate these rates, and we’ll find that the same trend continues. The reaction with catalase will produce oxygen at a faster rate than the reactions lacking catalase.

You may disagree, because after 120 seconds and 140 seconds the rate of oxygen produced with the help of the enzyme catalase drops to zero. However, this is only the case because all of the hydrogen peroxide is broken down. The trend would continue to show if there was an infinite amount of hydrogen peroxide available to be transformed.

We can now answer the question, which asks us to determine which reaction will have the lower rate of oxygen production. The correct response is “The rate is lower in the reaction without catalase.”

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