LS 1.5 Enzyme Activity,Protein Struc. & Func Post Test

Catalase is an enzyme that turns hydrogen peroxide into water and oxygen. A student fills seven test tubes with equal amounts of catalase and 5 mL of hydrogen peroxide at different temperatures. The student records the number of bubbles produced in each test tube in a graph. What can the student correctly conclude from the graph?

• The structure and function of the enzyme remain intact at 60°C.

• The structure and function of the enzyme change at 30°C.

• The enzyme works best when the temperature is 40°C.

• The enzyme works best when the temperature is 0°C.

Use the information to answer the question. The graphs show how a chemical reaction takes place in the cell of an organism both in the absence or presence of a catalyst, where Ea represents the activation energy of the reaction. What type of biomolecule most commonly composes a catalyst?

• carbohydrate

• lipid

• nucleic acid

• protein

The graphs show the rate of reaction vs. temperature and the rate of reaction vs. pH for an enzyme. Which statement provides the correct interpretation of the graphs?

• The enzyme works at a high level no matter how the temperature or pH changes.

• The enzyme works best at a certain temperature and is not affected by changes in pH.

• The enzyme works best at a certain pH and is not affected by changes in temperature.

• The enzyme works at a high level within specific ranges of temperature and pH.

Which statement is true about an enzyme?

• An enzyme can be reused after releasing the substrate as a product.

• An enzyme acts to slow down reactions in order to prevent protein mutations.

• An enzyme is made of a sequence of carbohydrates linked by peptide bonds.

• An enzyme binds to all types of substrates in order to speed up chemical reactions.

If the reaction temperature were to increase from 40°C to 63°C, the reaction rate would likely

• decrease, because the enzyme would become denatured.

• increase, because the kinetic energy would increase.

• decrease, because the enzyme would be used up.

• stay the same, because the rate of enzyme-catalyzed reactions is constant.

Which event will cause a protein to function incorrectly within a cell?

• A decrease in the amount of carbohydrates in the cell lowers the amount of available energy.

• A chemical causes the cell membrane to become more ridged to prevent water loss.

• A cell is exposed to a chemical that increases the rate at which RNA is produced.

• An increase in the internal temperature of the cell changes the protein’s shape.

What can the students conclude about the effect of temperature on rennin activity?

• Activity is greatest at temperatures above 50°C because higher temperatures increase the collision between molecules of the enzyme and the substrate.

• Activity is greatest at temperatures below 30°C because lower temperatures decrease the energy required for the reaction.

• Activity increases as temperature increases with optimum activity at 37°C at which point the enzyme is denatured, stopping enzyme activity completely.

• Activity increases as temperature increases with optimum activity at 37°C at which point activity decreases until the enzyme is denatured at over 50°C.

Letter C...

• active site
• enzymes
• substrate
• products

Letter E...

• active site
• enzyme
• substrate
• products

Which letter represents the enzyme?

• A

• B

• C

• D