Question

39) Aquaporins and most enzymes are similar in many aspects, but NOT in this:

A) They are specific for certain molecules

B) They are proteins

C) They are catalysts

D) They have three-dimensional (3-D) structure

40) Organisms do NOT use heat to overcome EA and speed up chemical reactions. Why not?

A) Heat would only speed up endergonic reactions

B) High temperature might denature cellular proteins

C) The energy barrier for most chemical reactions could not be surmounted by heat

D) The ΔG of the reaction would decrease

E) Reactants may be completely consumed, so that their free energy is destroyed

41) With respect to enzyme action, competitive inhibitors:

A) Prevent binding of the substrate by changing an enzyme’s shape

B) Increase the productivity of enzymes

C) Mimic enzymes and catalyze chemical reactions

D) Directly compete with the substrate for binding to the active site

42) What is true about enzymes?

A) One enzyme can recognize many substrates

B) An enzyme’s amino acid sequence determines its specific 3-D shape

C) Enzymes bind substrates irreversibly

D) During conversion of reactants into products, enzymes are used up

E) An enzyme can work equally well under acidic and alkaline conditions

8 of 9

43) A cell has made sufficient ATP via catabolism of glucose and now needs to decrease the rate of ADP phosphorylation. To slow down the rate of its own synthesis, ATP can:

A) Catalyze the conversion of ADP into an inactive form

B) Temporarily disassemble the mitochondrion

C) Act as a noncompetitive inhibitor of an enzyme in the metabolic pathway

D) Switch the ribose sugar in ADP for a deoxyribose sugar

E) Rearrange the order of the enzymes involved in the metabolic pathway

44) Cellular respiration is considered a redox process because:

A) Glucose becomes reduced

B) Electrons are stripped from CO2

C) Electrons from glucose are transferred to O2

D) H2O becomes oxidized

E) Electrons are transferred to a higher energy state

Answer 1

Aquaporins and most enzymes are similar in many aspects, but NOT in this:

D) They have three-dimensional (3-D) structure

Organisms do NOT use heat to overcome EA and speed up chemical reactions. Why not?

D) The ΔG of the reaction would decrease  

With respect to enzyme action, competitive inhibitors:

D) Directly compete with the substrate for binding to the active site

What is true about enzymes?

C) Enzymes bind substrates irreversibly

A cell has made sufficient ATP via catabolism of glucose and now needs to decrease the rate of ADP phosphorylation. To slow down the rate of its own synthesis, ATP can:

D) Switch the ribose sugar in ADP for a deoxyribose sugar

Cellular respiration is considered a redox process because:

C) Electrons from glucose are transferred to O2