LS 1.5 Enzyme Function & LS 1.7 Cell Membrane Transport Pre-Test

What is the effect of an enzyme on the energy of a chemical reaction?

• Enzymes increase the free energy of the products.

• Enzymes decrease the free energy of the reactants.

• Enzymes decrease the difference in energy between products and reactants.

• Enzymes decrease the activation energy of the reaction.

Which of the following is NOT a function of proteins?

• store and transmit genetic information

• help to fight disease

• control the rate of reactions

• move substances into or out of cells

Which of the following statements about enzymes is NOT true?

• Enzymes work best at a specified pH.

• All enzymes have the same shape as their substrates.

• Enzymes are proteins.

• The shape of an enzyme allows it to do its job.

Jules is designing an experiment to determine which temperature and pH the human enzyme pepsin, which acts in the stomach, is most effective at breaking apart proteins. As predicted by established ideas about enzymes, which hypothesis will MOST likely be supported by the results of the experiment?

• The enzyme is most effective at temperatures close to 37°C and under acidic conditions.

• The enzyme is most effective at temperatures close to 20°C and under acidic conditions.

• The enzyme is most effective at temperatures close to 37°C and under alkaline conditions.

• The enzyme is most effective at temperatures close to 12°C and under alkaline conditions.

• The enzyme is most effective at temperatures close to 37°C and at any pH.

The enzyme carbonic anhydrase is a protein that binds to two small molecules: water and carbon dioxide. By holding the two molecules in the proper position, the enzyme allows the two molecules to react to form a product, carbonic acid. The enzyme then releases the product and becomes available to catalyze the same reaction once again. How does carbonic anhydrase change the reaction between carbon dioxide and water?

• It increases the total energy released.

• It alters the structure of the product.

• It decreases the activation energy.

• It decreases the total mass of the system.

After the enzyme releases a molecule of carbonic acid, what MOST LIKELY will occur next?

• The enzyme will be degraded, or broken apart.

• The enzyme will repeat its function of binding reactants and releasing carbonic acid.

• The enzyme will take on a new function and catalyze a different chemical reaction.

• The enzyme will take on a new function that does not involve chemical reactions, such as providing cell structure or support.

The results of an experiment show that as temperature increases, enzyme activity decreases. Which graph correctly displays these findings?

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The diagram below illustrates a biochemical process that occurs in organisms. The substance labeled catalyst also is known by what other name?

• antibody

• enzyme

• ion

• inorganic compound

The graph shows the progress of a chemical reaction with and without the presence of an enzyme. Analyze the data. Which statement accurately reflects what is shown in the graph?

• The presence of the enzyme decreases the activation energy.

• The presence of the enzyme decreases the change in free energy.

• The presence of the enzyme decreases the energy of the products.

• The presence of the enzyme prevents the reaction from progressing.

Utilize a model of a cell plasma membrane to compare the various types of cellular transport and test predictions about the movement of molecules into or out of a cell based on the homeostasis of energy and matter in cells. Which of the following describes the process?

• The model shows the process of active transport because the solute particles are moving from an area of low concentration to an area of high concentration.

• The model shows the process of bulk transport because the solute particles are moving from an area of low concentration to an area of high concentration.

• The model shows the process of diffusion because solute particles are moving from an area of high concentration to an area of low concentration.

• The model shows the process of osmosis because the solute particles are moving from an area of high concentration to an area of low concentration.