QCM : Fundamentals of Acid-Base Balance — 9 questions

Questions et réponses du QCM

1. What is a key feature of pH regulation in biological systems?

It primarily controls blood pressure and fluid balance
It regulates the synthesis of DNA and proteins directly
It determines the oxygen-carrying capacity of hemoglobin
It ensures that hydrogen ion concentration remains stable to support enzymatic activity

It ensures that hydrogen ion concentration remains stable to support enzymatic activity

Explication

The key feature of pH regulation is its role in maintaining the stability of hydrogen ion concentration, which is essential for enzymatic activity and biochemical stability. The source emphasizes that small fluctuations in hydrogen ion levels can significantly impact vital processes, underscoring the importance of pH homeostasis.

2. What is the main reason maintaining blood pH within the narrow range of 7.35 to 7.45 is critical for human health?

Because it ensures proper enzyme activity and biochemical processes.
Because deviations have no significant effects on bodily functions.
Because it prevents the breakdown of hydrogen ions.
Because it increases the production of acids in metabolism.

Because it ensures proper enzyme activity and biochemical processes.

Explication

Maintaining blood pH within 7.35-7.45 is vital because even minor deviations can impair enzyme activity and disrupt biochemical processes essential for survival.

3. Who is credited with discovering or proposing the concept of the proton as the nucleus of hydrogen?

Ernest Rutherford
Niels Bohr
Marie Curie
J.J. Thomson

Ernest Rutherford

Explication

Ernest Rutherford is credited with discovering the nucleus of the atom, which in the case of hydrogen is the proton. The source states that 'The proton is the electropositive nucleus of ordinary hydrogen,' and historically, Rutherford's experiments led to the understanding of the atomic nucleus. The other options are notable scientists but are associated with different discoveries: Thomson with the electron, Bohr with the Bohr model of the atom, and Curie with radioactivity. Therefore, Rutherford is the correct attribution for the concept of the nucleus, including the proton in hydrogen.

4. Who is credited with proposing the concept of the proton as the nucleus of hydrogen?

James Clerk Maxwell in 1861.
Henry Moseley in 1913.
Gilbert N. Lewis in 1916.
Anatole Shimony in 1920.

Anatole Shimony in 1920.

Explication

Anatole Shimony proposed the concept of the proton as the nucleus of hydrogen in 1920, which is fundamental in understanding atomic structure.

5. Which condition is characterized by a blood pH lower than 7.35?

Alkalosis.
Acidosis.
Neutral pH.
Metabolic alkalosis.

Acidosis.

Explication

Acidosis occurs when blood pH drops below 7.35, indicating excess acidity, which can impair physiological functions.

6. What does the term 'buffer system' in the context of acid-base balance refer to?

A mechanism that maintains blood pH by neutralizing excess acids or bases.
A way to increase acid production in metabolism.
An enzyme that catalyzes hydrogen ion dissociation.
A structure that prevents hydrogen ions from dissociating.

A mechanism that maintains blood pH by neutralizing excess acids or bases.

Explication

Buffer systems help maintain pH stability by neutralizing excess acids or bases, crucial for physiological pH regulation.

7. What is a characteristic of a strong acid in terms of its dissociation?

It dissociates completely in solution.
It dissociates partially in solution.
It does not dissociate at all.
It only dissociates at high pH levels.

It dissociates completely in solution.

Explication

Strong acids dissociate completely in solution, releasing all their available hydrogen ions, which influences pH significantly.

8. Which component of hemoglobin contributes to the buffering capacity of blood?

The iron ion (Fe2+).
The globin protein.
The amino acids within hemoglobin.
The amino group in hemoglobin.

The amino group in hemoglobin.

Explication

The amino groups in hemoglobin can accept hydrogen ions, contributing to the blood's buffering capacity to maintain pH balance.

9. What does the 'pK' value of a buffer system indicate?

The pH at which the buffer system is at its maximum capacity.
The pH at which the buffer fully dissociates.
The pH at which the buffer system does not respond.
The pH where the buffer system is ineffective.

The pH at which the buffer system is at its maximum capacity.

Explication

The pK value indicates the pH at which a buffer system can best resist changes in pH, i.e., its maximum buffering capacity.

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pH regulation — importance?

Maintains enzyme activity and biochemical stability.

pH — definition?

Measure of hydrogen ion concentration.

Hydrogen ion — role?

Determines acidity and influences pH.

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