Question 1

Refer to the first image. Which type of enzyme inhibition is depicted in the lower row, and what is the main characteristic that distinguishes it from the upper row?

Accepted Answer

Competitive inhibition; the inhibitor binds to the active site, directly competing with the substrate.

Question 2

Based on the second image, which hormone is primarily responsible for increasing sodium reabsorption in the kidney, and what is the physiological effect of this action?

Accepted Answer

Aldosterone; it increases sodium reabsorption, leading to increased blood volume and blood pressure.

Question 3

Refer to the third image. Which class of antibiotics inhibits bacterial cell wall synthesis, and what is the main structural component targeted?

Accepted Answer

Beta-lactams; they target peptidoglycan synthesis.

Question 4

In the fourth image, which hormone is a direct precursor to both cortisol and aldosterone in the steroidogenesis pathway?

Accepted Answer

Progesterone

Question 5

Refer to the fifth image. Which metabolic pathway is illustrated, and what is the primary physiological purpose of this pathway?

Accepted Answer

Gluconeogenesis; to synthesize glucose from non-carbohydrate precursors.

Question 6

Based on the sixth image, what is the net ATP cost to the liver for converting two molecules of lactate to one molecule of glucose via the Cori cycle?

Accepted Answer

$$6$$ ATP

Question 7

Refer to the seventh image. What is the main fate of fatty acids during periods of fasting, and which organ is primarily responsible for this process?

Accepted Answer

Fatty acids are broken down via beta-oxidation in the liver to produce acetyl-CoA for energy.

Question 8

Based on the eighth image, which enzyme is most likely to be elevated in the blood following a myocardial infarction, and why?

Accepted Answer

Creatine kinase (CK); because it is released from damaged cardiac muscle cells.

Question 9

Refer to the ninth image. Which type of enzymatic reaction involves the transfer of a phosphate group from ATP to a substrate, and what is the representative enzyme for this reaction?

Accepted Answer

Transfer of chemical groups; kinase

Question 10

In the tenth image, what is the significance of the transition between the T (tense) and R (relaxed) states in allosteric enzymes, and how does this relate to enzyme regulation?

Accepted Answer

The T state is inactive and has low affinity for substrate, while the R state is active and has high affinity for substrate; this transition is a key mechanism of allosteric regulation.

Question 11

A patient is given a drug that acts as a competitive inhibitor for an enzyme. Based on the first image, what would be the expected effect on the enzyme's activity, and how could this inhibition be overcome?

Accepted Answer

The enzyme's activity would decrease; inhibition can be overcome by increasing substrate concentration.

Question 12

In the context of the second image, what is the effect of increased angiotensin II on blood pressure, and through which mechanisms does it act?

Accepted Answer

It increases blood pressure by promoting vasoconstriction and stimulating aldosterone release.

Question 13

Which of the following best describes the relationship between the Cori cycle (sixth image) and muscle metabolism during intense exercise?

Accepted Answer

The Cori cycle allows lactate produced in muscles during anaerobic glycolysis to be converted back to glucose in the liver, supporting continued muscle activity.

Question 14

Based on the fourth image, which hormone is synthesized from both progesterone and deoxycorticosterone, and what is its primary function?

Accepted Answer

Cortisol; it regulates glucose metabolism and the stress response.

Question 15

Which enzyme, as shown in the eighth image, is most useful for diagnosing liver disease, and why?

Accepted Answer

Glutamate dehydrogenase (GDH); because it is released from damaged liver cells.

Human Physiology: Molecular Interactions, Metabolism, and System Integration

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