Which of the following most accurately describes the transmembrane signaling process involved in steroid hormone action?

Correct Answer: C

Rationale: Steroid hormone action involves diffusion into the cytoplasm and binding to an intracellular receptor (C), as lipophilic steroids (e.g., cortisol) cross membranes, bind nuclear receptors, and regulate gene expression. Option A describes tyrosine kinase receptors (e.g., insulin). Option B fits G-protein-coupled receptors (e.g., epinephrine). Option D involves JAK-STAT pathways (e.g., cytokines), not steroids. Option E (original) about ion channels applies to neurotransmitters. This genomic mechanism, slow but sustained, contrasts with rapid membrane receptor signaling, altering protein synthesis for effects like anti-inflammation, critical in endocrinology and pharmacology.

Correct Answer: D

Rationale: The pH value is the negative log of the hydrogen ion (H⁺) concentration (D), defined as pH = -log[H⁺], measuring acidity (e.g., pH 7 = 10⁻⁷ M H⁺). Option A (log[OH⁻]) and B (-log[OH⁻]) relate to pOH, not pH. Option C (log[H⁺]) omits the negative, yielding incorrect values. Option E (original) about ratios is unrelated. This logarithmic scale, rooted in the water dissociation constant (pH + pOH = 14), quantifies acidity impacting drug ionization (e.g., weak acids in stomach), a cornerstone of pharmaceutical chemistry.

Correct Answer: A

Rationale: The particle size of the dispersed solid in a suspension is usually greater than 0.5 μm (A). Suspensions are heterogeneous systems with insoluble particles large enough to settle (e.g., oral antacids), distinguishing them from colloids (0.001-0.5 μm). Options B (0.4 μm), C (0.3 μm), and D (0.2 μm) fall below this threshold, while 0.1 μm (original E) is even smaller. This size ensures visible dispersion, requiring shaking before use, and impacts stability and bioavailability, as larger particles dissolve slower, a key consideration in pharmaceutical suspensions.

Correct Answer: C

Rationale: Pulverization by intervention (C) is typically used to mill camphor, adding a volatile solvent (e.g., alcohol) to reduce it to a fine powder, then evaporating the solvent, overcoming camphor's waxy nature. Trituration (A) grinds without solvent, less effective here. Levigation (B) uses a liquid to make a paste, not ideal for camphor. Geometric dilution (D) mixes powders, not mills. Attrition (original E) is mechanical grinding, less specific. This method ensures uniformity for incorporation into ointments or inhalants, leveraging camphor's volatility for pharmaceutical use.

Correct Answer: C

Rationale: Cellulose acetate phthalate (C) is used to coat enteric tablets, dissolving above pH 6 (intestine), protecting drugs (e.g., aspirin) from gastric acid. Hydroxypropyl methyl cellulose (A) and carboxymethyl cellulose (B) are film-formers, not enteric-specific. No option D or original E exists. This pH-dependent coating delays release, reducing gastric irritation or degradation, critical for targeted delivery and efficacy in oral formulations, leveraging gastrointestinal pH gradients.