Chapter 8 test your understanding

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to a. add more of the enzyme. b. heat the solution to 90°C. c. add more substrate. d. add an allosteric inhibitor. e. add a noncompetitive inhibitor.

a

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______. a. exergonic; spontaneous d. work; energy b. exergonic; endergonic e. entropy; enthalpy c. free energy; entropy

b

Which of the following metabolic processes can occur without a net influx of energy from some other process? a. ADP i S ATP H2O b. C6H12O6 6 O2 S 6 CO2 6 H2O c. 6 CO2 6 H2O S C6H12O6 6 O2 d. amino acids S protein e. glucose fructose S sucrose

b

Most cells cannot harness heat to perform work because a. heat is not a form of energy. b. cells do not have much heat; they are relatively cool. c. temperature is usually uniform throughout a cell. d. heat can never be used to do work. e. heat must remain constant during work.

c

Some bacteria are metabolically active in hot springs because a. they are able to maintain a lower internal temperature. b. high temperatures make catalysis unnecessary. c. their enzymes have high optimal temperatures. d. their enzymes are completely insensitive to temperature. e. they use molecules other than proteins or RNAs as their main catalysts.

c

Using a series of arrows, draw the branched metabolic reaction pathway described by the following statements, and then answer the question at the end. Use red arrows and minus signs to indicate inhibition. L can form either M or N. M can form O. O can form either P or R. P can form Q. R can form S. O inhibits the reaction of L to form M. Q inhibits the reaction of O to form P. S inhibits the reaction of O to form R. Which reaction would prevail if both Q and S were present in the cell in high concentrations? a. L SM c. L SN e. R S S b. M SO d. O S P

c

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur? a. Additional product will be formed. b. Additional substrate will be formed. c. The reaction will change from endergonic to exergonic. d. The free energy of the system will change. e. Nothing; the reaction will stay at equilibrium.

e