Enzyme Regulation: Zymogen Activation Practice Questions

Question 1

Digestion of proteins is initiated by:

Accepted Answer

Pepsin

Answer

Amylase

Answer

Sucrase

Answer

Chymotrypsin

Question 2

A patient presents with respiratory distress and is diagnosed with panacinar emphysema. Which of the following is deficient?

Accepted Answer

Alpha-1 antitrypsin

Answer

Surfactant

Answer

Albumin

Answer

Type II pneumocytes

Question 3

Which of the following statements best describes the mechanism of action of insulin on target cells?

Accepted Answer

Insulin binds to a transmembrane receptor on the outer surface of the plasma membrane, activating the tyrosine kinase in the cytosolic domain of the receptor.

Answer

Insulin binds to a receptor on the outer surface of the plasma membrane, activating adenylate cyclase through the Gs protein.

Answer

Insulin binds to a cytoplasmic receptor and is transferred as a hormone receptor complex to the nucleus to modulate gene expression.

Answer

Insulin enters the cell and causes the release of calcium ions from intracellular stores.

Question 4

A 35-year-old woman with a long history of dyspnea, chronic cough, sputum production, and wheezing dies of respiratory failure following a bout of lobar pneumonia. She was not a smoker or an alcoholic. Which of the following underlying conditions is most likely associated with the pathologic changes shown in the lung autopsy?

Accepted Answer

Alpha-1 antitrypsin deficiency

Answer

Antibodies against type 4 collagen (associated with Goodpasture syndrome)

Answer

Cystic fibrosis (a genetic disorder affecting the lungs)

Answer

Mutation in dynein arms (associated with primary ciliary dyskinesia)

Question 5

Inactive precursors of enzymes are known as:

Accepted Answer

Proenzymes

Answer

Apoenzymes

Answer

Coenzymes

Answer

Holoenzymes

Question 6

All of the following are true about blood coagulation, except which of the following?

Accepted Answer

Factor X directly activates both intrinsic and extrinsic pathways.

Answer

Calcium is required in several steps of coagulation.

Answer

Extrinsic pathway is activated by tissue factor released from damaged tissues.

Answer

Intrinsic pathway can be activated in vitro by contact with collagen.

Question 7

Which of the following is an example of allosteric inhibition?

Accepted Answer

Inhibition of PFK-1 by citrate

Answer

Decreased synthesis of glucokinase by glucagon

Answer

Inactivation of glycogen synthase by phosphorylation

Answer

None of the options

Question 8

How do enzymes function in biochemical reactions?

Accepted Answer

Decrease in activation energy

Answer

Increase in activation energy

Answer

Shift equilibrium constant

Answer

Provide energy to the reaction

Question 9

Enzyme activity is expressed as?

Accepted Answer

Micromoles/min

Answer

Millimoles/lit

Answer

Milli gm/lit

Answer

Mg/dl

Question 10

What is the specific activity of an enzyme?

Accepted Answer

Enzyme units per mg of protein

Answer

Concentration of substrate transformed per minute

Answer

Enzyme units per mg of substrate

Answer

Limit of enzyme per gram of substrate

Enzyme Regulation: Zymogen Activation — MCQs

Enzyme Regulation: Zymogen Activation — MCQs

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