Understanding of chemistry basics.
1. The relative concentrations of reactant and product found when a reaction reaches equilibrium reflects_____.
a. the speed at which one compounded can be converted to another
b. whether or not an enzyme is present in the system.
c. the relative free energies of product and reactant
d. the degree to which a cell is in need of a particular substance
e. the difficulty of achieving the transition state between reactant and product
2. The amount of disorder in the universe tends to____
a. increase
b. decrease
c. remain the same.
d. decrease until reaching a minimum and then remain the same
e. fluctuate
3. Which of the following is true of a reaction at equilibrium?
a. the reactant and product cease to react
b. the rate of the forward reaction equals the rate of the reverse reaction
c. the concentration of the substrate equals the concentration of the product.
D. the system has reached a state of minimum entropy.
e. the system is highly unstable.
4. 2- phosphoglycerate (2PG) has significantly more free energy than does 3- phosphoglycerate (3PG). A Scientist places equal amounts of the two compounds in solution with an enzyme that allows their inter conversion. At equilibrium he or she would observe a______
a. a solution of pure 2PG
b. a solution of pure 3PG
c. a mixture of primarily 2PG with a small amount of 3PG
d. a mixture of primarily 3PG with a small amount of 2PG
5. In the hypothetical chemical reaction A B, suppose the compound B has less energy than compound A. If the temperature at which the reaction takes place is raised from 100 C to 900C, the concentration of B at equilibrium will ______, and the length of time it take to achieve equilibrium will______.
a. decrease; decrease
b. decrease; increase
c. increase; decrease
d. increase; increase
e. remain the same; remain the same
6. which of the following is not changed by the activity of an enzyme during a chemical reaction?
a. the activation energy of a reaction
b. the relative concentrations of reactant and product at equilibrium
c. the entropy of the universe
d. the precise conformation of either reactants or products
e. the speed at which the reaction takes place
7. Given the hypothetical chemical reaction, A B. The relative amounts of A and B at equilibrium are determined by their______, whereas the speed of the reaction is determined by the_______.
a. free energies; amount of energy it takes place to achieve the transition state
b. free energies; relative free energies as well
c. concentrations at the beginning of the reaction; free energy of the reactants
d. concentration at the beginning of the reaction; free energy of the products
8. The rate of an enzymatic reaction is generally faster if the____
a. temperature of the solution is over 1000C
b. product has less energy than the reactant
c. energy of activation is low.
d. Concentration of both reactant and product are high
e. reaction takes place in a low pH solution
9. Enzymes function as catalysts by____.
a. changing the relative concentrations of reactant and product at equilibrium
b. orienting substrates to improve the efficiency of reactions
c. straining the bonds within the substrates
d. permitting forward, but not reverse , reactions
e. b and c
10. Enzymes lower the activation energy of reactions by______.
a. straining the bonds within the substrates
b. coupling two reactions
c. permitting reactions to go in one direction only
d. raising the temperature of the reactants
e. b and c