Biology 201 Chapter 3 Quiz Study Notes

The activation energy of a biochemical reaction

A. is lowered when an appropriate enzyme is present. B. is the reason why many reactions do not occur without an enzyme. C. has to be invested to begin the reaction A, B, and C are all correct

Which of the following statements about reactions is FALSE?

The products of a reaction may have less free energy (G) than the reactants. The products of a reaction may have more free energy (G) than the reactants. Reversible reactions tend to approach a dynamic equilibrium. Many biochemical reactions in the cell are reversible. NONE OF THE ABOVE ARE TRUE!!!

Which of the following statements about exergonic reactions is FALSE?

Their products have more energy than the reactants.

An orderly series of biochemical reactions with specific enzymes acting at each step is characteristic of

a metabolic pathway.

NAD+ and FAD

are coenzymes of enzymes acting in Redox reactions. are organic molecules.

Enzymes

bind substrates at their active site. act as catalysts. are proteins. are reaction-specific. All of the above

An enzyme may lower the activation energy of a biochemical reaction by

bringing the substrates close together at the active site. bringing the substrates into a favorable orientation toward each other. participating in the reaction temporarily, but coming out of it unchanged.

Feedback inhibition in the metabolism of cells

is usually exerted through allosteric effects on enzymes. often involves the first enzyme of a metabolic pathway. is used to regulate the activity of many metabolic pathways. frequently employs the end-product of a metabolic pathway as allosteric inhibitor.

When a biochemical reaction has reached its equilibrium

the change in free energy is zero (ΔG=0). the forward and reverse reaction proceed at the same rate. Both of the above are true

The activity of an enzyme may be increased by

the presence of molecules that fit into allosteric sites.