Oxford University Press | Online Resource Centre

Choose your answer by clicking the radio button next to your choice and then press 'Submit' to get your score.

Which of the following statements about the regulation of a metabolic pathway is correct?

a) Most metabolic pathways are not regulated.

b) Regulation of metabolic pathways always involves changing the amount of enzymes.

c) Metabolic regulation always depends on control by hormones.

d) Most metabolic pathways are regulated.

Which of the following correctly exhibits an example of metabolic control?

a) In cases where the direction of a metabolic pathway has to be reversed the pathway is controlled at an irreversible step.

b) Regulatory changes in a pathway always occur slowly over periods of several hours or more.

c) Enzymes which are controlled are always those which catalyse the first reaction of the pathway.

d) Most enzyme control mechanisms are irreversible.

Which of the following statements about the mechanism of allosteric control of enzyme activity is correct?

a) Allosteric enzymes are single-subunit enzymes.

b) Allosteric enzymes show a greater sensitivity to changes in substrate concentration than classical type enzymes with hyperbolic kinetics.

c) Allosteric enzymes show Michaelis-Menten kinetics.

d) Allosteric enzymes show a reduced sensitivity to changes in substrate concentration than classical type enzymes with hyperbolic kinetics.

Which of the following statements about the control of enzyme activity by phosphorylation is correct?

a) Phosphorylation of an enzyme is not a reversible process since it is a covalent modification.

b) Phosphorylation of an enzyme occurs by protein phosphatases.

c) Phosphorylation of an enzyme is an intracellular process and cannot occur in response to external signals.

d) Phosphorylation of an enzyme results in a conformational change.

Which of the following statements about the integration of fat and carbohydrate metabolism control in diabetes mellitus is correct?

a) High insulin/glucagon ratio inactivates lipolysis in liver.

b) High insulin/glucagon ratio activates lipolysis in adipocytes.

c) Low insulin/glucagon ratio activates lipolysis in adipocytes.

d) Insulin-dependent glucose transporters are recruited to their functional membrane site by low insulin levels.

Oxford University Press, Online Resource Centre, Chapter 16.