Download Quiz (B) 1. Which of the following statements concerning enzyme

Quiz (B)
1. Which of the following statements concerning enzyme regulation is incorrect:
a. Heterotropic effectors; some enzymes are regulated by their own product.
b. Allosteric effectors always increase K0.5
c. induction or repression the enzyme synthesis, example insulin.
d. Homotropic effectors; some enzymes are regulated by their own substrate.
e. Covalent modification (phosphorylation the enzyme)
2. Allosteric Homotropic effectors:
a. substrate itself serves as an effector.
c. another enzyme serves as an effector.
b. the effector different from the substrate.
d. Hormone serves as an effector.
3. Some enzymes require the presence of a non-protein substance (inorganic molecules) if they are to
catalyse a reaction. Which of the following terms is the best general term for such a substance?
a. prosthetic group
c. cofactor
b. coenzyme
d. effector
4. A competitive inhibitor of an enzyme-catalyzed reaction:
a. increases KM and unchanged Vmax.
c. decrease Vmax and decrease Km.
b. decrease Vmax and unchanged Km.
d. increase Km and decrease Vmax.
5. Reaction with no inhibitor has Vmax=500, Km=2; so the Km with present noncompetitive inhibitor
equal:
a. 250
b. 500
c. 2
d. 1
6. Km value is high that is mean:
a. low affinity of the enzyme for substrate
c. the affinity of the enzyme for substrate unchanged
7. The enzymes are sensitive to:
a. Changes in pH
c. Both a and b
b. high affinity of the enzyme for substrate
d. None of these
b. Changes in temperature
d. None of these
8. penicillin inhibit enzyme to prevent bacteria cell wall synthesis that is called :
a. antibiotic of β-lactam ring
b. clavulanic acid
c. β-lactamase
c. Trans-peptidase
9. The substrate and chemical reaction for pyruvate decarboxylase are:
a. pyruvate & add carboxylase group (ligases) respectively
b. lactate & add carboxylase (oxidoreductase) respectively
c. pyruvate & remove of carboxylase group (lyases) respectively
d. urea & remove amino group (hydrolases) respectively
10. Enzymes non-following Michaelis-Menten kinetics show:
a. hyperbolic curve such as myoglobin
c. sigmoidal curve such as Hb
b. Rock of curve
d. dose curve