Enzymes

1. Urease catalyzes the following reaction:

   H₄CN₂O + H₂O ® CO₂ + 2NH₃.   (Urea + Water ® Carbon Dioxide + Ammonia)

   What happened to the pH when urease was added to urea and water?

   a. It decreased (became more acidic).     
   b. It increased (became more basic).  
   c. It remained neutral (pH 7).

2. What happened to show that the reaction above occurred, that is, what did you see?
3. What happened to the amount of time needed when less urease was added to the test tubes?

   a. The reaction did not occur.     
   b. The reaction occurred but was not detectable.     
   c. The reaction took longer to detect but eventually produced the same results as when more urease was used.     
   d. The reaction produced intermediate results by the time the experiment was completed.

4. Catalase catalyzes the conversion of H₂O₂ to 2H₂O + O₂. When you did this experiment, how could you tell that a reaction was occurring?
5. Which produced the fastest rate of reaction?

   a. Catalase + NaOH (a base) + H₂O₂ 
   b. Catalase + HCl (an acid) + H₂O₂ 
   c. Catalase + H₂O + H₂O₂ 
   d. Both a and b were fast, c was the slowest.    
   e. Both a and c were fast, b was the slowest.

6. When you did the experiment using rennin, how could you tell that a reaction occurred?
   
7. Which produced the fastest rate of reaction?

   a. rennin + cold milk     
   b. boiled rennin + warm milk
   c. rennin + warm milk 
   d. Both a and b were fast, c was the slowest.     
   e. Both a and c were fast, b was the slowest.

8. What will happen to the rate of an enzyme reaction as it is heated from very cold (near freezing) to very hot (near boiling)?

   a. it will remain the same
   b. it will increase, then decrease
   c. it will decrease     
   d. it will decrease, then increase     
   e. it will increase, then level off

9. What will happen to the rate of an enzyme reaction as the concentration of substrate is increased from zero?

   a. it will remain the same     
   b. it will increase, then decrease
   c. it will decrease    
   d. it will decrease, then increase     
   e. it will increase, then level off

10. What will happen to the rate of an enzyme reaction as the concentration of enzyme is increased from zero?

    a. it will remain the same     
    b. it will increase, then decrease
    c. it will decrease     
    d. it will decrease, then increase     
    e. it will increase, then level off

11. At which pH do enzymes function best?

    a. low (acid)     
    b. neutral     
    c. high (basic)     
    d. There is no effect of pH on enzyme activity.
    e. The optimal pH depends on the particular enzyme.

12. Which should have the least reaction?

    a. Rennin and cold milk     
    b. rennin and warm milk     
    c. boiled rennin and warm milk
    d. both a and b

13. Discuss the effect of temperature on enzyme reactions and refer to the laboratory exercise in your discussion. Be sure to explain why temperature has the effect that it does. Use whole sentences in your answer.
    
14. Discuss the effect of pH on enzyme reactions and refer to the laboratory exercise in your discussion. Be sure to explain why pH has the effect that it does on enzyme reactions. Use whole sentences in your answer.
    
15. Discuss the effect of varying enzyme concentration on the rate of reactions. Refer to the laboratory exercise in your discussion by mentioning the name of the enzyme that you used and telling what the enzyme did. Be sure to explain why different enzyme concentrations had the effect that they did.