Unit 4 Target 1: Enzymes Quiz

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by providing an alternative pathway with lower activation energy, allowing the reaction to occur more quickly. This is different from other options such as lipid, molecule, or element, which do not have the specific property of accelerating chemical reactions.

Enzymes are essential for speeding up chemical reactions in the body. Without enzymes, these reactions would occur at a significantly slower rate, which would not be sufficient to support the necessary life processes. Therefore, the correct answer is that without enzymes, the chemical reactions in the body would occur too slowly to support life processes.

Activation energy is the term used to describe the energy needed to get a reaction started. It is the minimum amount of energy required for a chemical reaction to occur. This energy is needed to break the bonds of the reactant molecules and initiate the formation of new bonds in the product molecules. Activation energy acts as a barrier that must be overcome for a reaction to proceed. Once the activation energy is surpassed, the reaction can continue on its own without any additional energy input.

Enzymes are catalysts that speed up chemical reactions in living cells. They do so by lowering the activation energy required for the reaction to occur. This means that enzymes increase the rate or speed at which the reaction takes place. Enzymes themselves are not consumed or changed during the reaction, and they do not affect the products or the final outcome of the reaction. Therefore, the correct answer is that enzymes affect the speed of the reaction.

The graph shows the energy profile of three reactions. Reaction 3 is indicated by the highest peak, suggesting that it requires a higher activation energy compared to reaction 2. However, it is not the same as reaction 1 because it occurs at a higher energy level. The fact that reaction 3 has a higher activation energy suggests that it may have occurred in the presence of a catalyst, which lowers the activation energy and speeds up the reaction.

Enzymes work best at a specified pH, which means that they function optimally within a specific pH range. Enzymes are indeed proteins, as they are composed of amino acids. The shape of an enzyme is crucial for its function, as it allows the enzyme to bind with its specific substrate and catalyze a chemical reaction. However, enzymes do not have the same shape as their substrates. Instead, enzymes have a unique three-dimensional structure that complements the shape of their substrates, allowing for a specific and efficient interaction.

The active site of an enzyme is where the reactant fits into the enzyme. This site is specifically shaped to accommodate the reactant molecule, allowing for a precise and specific interaction between the enzyme and the substrate. The active site provides a favorable environment for the reaction to occur, facilitating the formation of the enzyme-substrate complex and the subsequent conversion of the substrate into product. The specificity and complementary shape of the active site ensure that only the correct reactant molecule can bind and undergo the enzymatic reaction.

Enzymes speed up chemical reactions by reducing activation energy. Activation energy is the energy required to start a chemical reaction. Enzymes lower this energy barrier, making it easier for the reaction to occur. They do this by binding to the reactant molecules and bringing them closer together, allowing them to interact more easily and increasing the likelihood of a successful reaction. By reducing the activation energy, enzymes increase the rate of the reaction without being consumed or permanently altered in the process.

Antacids work by increasing the pH of the stomach, making it more alkaline. This change in pH can affect the structure and function of pepsin, which is an enzyme that works best in an acidic environment. The active site of an enzyme is the region where the substrate binds and the chemical reaction takes place. When the pH increases, the active site of pepsin undergoes a conformational change, altering its shape. This change in shape can prevent pepsin from effectively binding to and digesting proteins, reducing the efficiency of protein digestion.

Catalysts are substances that speed up the rate of a chemical reaction by lowering the activation energy required for the reaction to occur. They do not slow down the rate of chemical reactions. While some catalysts may be enzymes, not all catalysts are enzymes. Catalysts are not used up during a chemical reaction, as they are not consumed in the reaction and can be used repeatedly. Therefore, the correct statement is that catalysts lower the activation energy of a chemical reaction.

The correct answer is Student 2; enzymes are not depleted as a reaction progresses. Enzymes are catalysts that facilitate chemical reactions without being consumed in the process. Therefore, the concentration of the enzyme in the test tube will remain the same as the reaction progresses.