A pH of 4 is how many times as acidic as a pH of 7?

Correct Answer: C

Rationale: To calculate how many times more acidic a pH of 4 is compared to a pH of 7, we use the formula 10^(pH difference). In this case, the pH difference is 7-4 = 3. Therefore, 10^3 = 1000. So, a pH of 4 is 1000 times more acidic than a pH of 7. Choice A (10) is incorrect because it represents a pH difference of 1, not 3. Choice B (100) is incorrect as it represents a pH difference of 2. Choice D (10,000) is incorrect as it represents a pH difference of 4.

Correct Answer: C

Rationale: The primary buffer system in the intracellular fluid (ICF) is bicarbonate/carbonic acid. This system helps maintain the pH balance within cells by neutralizing any excess acids or bases. Bicarbonate acts as a weak base, while carbonic acid acts as a weak acid, allowing them to buffer changes in pH effectively. Haemoglobin (choice A) primarily functions as an oxygen carrier in the blood. Phosphate (choice B) is a buffer system in the urine and plays a role in buffering pH in the renal system. Proteins (choice D) can act as buffers in the blood, but they are not the primary buffer system in the ICF. Therefore, the correct choice is C as it directly relates to the primary buffer system within the intracellular fluid.

Correct Answer: C

Rationale: The correct answer is C: PO 3- secretion. The kidneys regulate pH by either excreting H+ ions or reabsorbing HCO3- ions. NH3 secretion helps in buffering H+ ions, while HCO3- excretion helps in regulating blood pH. PO 3- secretion does not directly affect pH regulation in the extracellular fluid. Hence, it is not modified by the kidneys to regulate pH.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Calculate the ratio: [HCO3-] / [CO2] = 20/2 = 10 2. Normal ratio is 20/1, so a ratio of 10 indicates a decrease in HCO3-. 3. Decrease in HCO3- leads to increased acidity, indicating acidosis. 4. Since the issue is not related to CO2 levels, it is uncompensated respiratory acidosis. Summary: - Choice A is correct due to the low [HCO3-] / [CO2] ratio indicating acidosis. - Choices B, C, and D are incorrect as they do not match the given scenario of respiratory acidosis.

Correct Answer: C

Rationale: Rationale: The correct answer is C: chloride. The serum anion gap is calculated by subtracting the sum of bicarbonate and chloride from sodium. Chloride is the primary anion contributing to the serum anion gap, as it plays a crucial role in maintaining electrical neutrality. Phosphate (A) and bicarbonate (B) are not included in the calculation of the serum anion gap. Sodium (D) is a cation, not an anion, so it does not directly contribute to the anion gap. Therefore, chloride is the correct answer as it is a major anion contributing to the serum anion gap.